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  • 51.
    Fredenberg, Erik
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Åslund, Magnus
    Sectra Mamea AB.
    Cederström, Björn
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Lundqvist, Mats
    Sectra Mamea AB.
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Observer model optimization of a spectral mammography system2010In: Medical Imaging 2010: Physics of Medical Imaging / [ed] Samei E; Pelc NJ, 2010, Vol. 7622, article id 762210Conference paper (Refereed)
    Abstract [en]

    Spectral imaging is a method in medical x-ray imaging to extract information about the object constituents by the material-specific energy dependence of x-ray attenuation. Contrast-enhanced spectral imaging has been thoroughly investigated, but unenhanced imaging may be more useful because it comes as a bonus to the conventional non-energy-resolved absorption image at screening; there is no additional radiation dose and no need for contrast medium. We have used a previously developed theoretical framework and system model that include quantum and anatomical noise to characterize the performance of a photon-counting spectral mammography system with two energy bins for unenhanced imaging. The theoretical framework was validated with synthesized images. Optimal combination of the energy-resolved images for detecting large unenhanced tumors corresponded closely, but not exactly, to minimization of the anatomical noise, which is commonly referred to as energy subtraction. In that case, an ideal-observer detectability index could be improved close to 50% compared to absorption imaging. Optimization with respect to the signal-to-quantum-noise ratio, commonly referred to as energy weighting, deteriorated detectability. For small microcalcifications or tumors on uniform backgrounds, however, energy subtraction was suboptimal whereas energy weighting provided a minute improvement. The performance was largely independent of beam quality, detector energy resolution, and bin count fraction. It is clear that inclusion of anatomical noise and imaging task in spectral optimization may yield completely different results than an analysis based solely on quantum noise.

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  • 52. Fröberg, Asa
    et al.
    Mårtensson, Mattias
    KTH, School of Technology and Health (STH), Medical Engineering.
    Larsson, Matilda
    KTH, School of Technology and Health (STH), Medical Engineering.
    Janerot-Sjöberg, Birgitta
    KTH, School of Technology and Health (STH), Medical Engineering.
    D'Hooge, Jan
    Arndt, Anton
    High variability in strain estimation errors when using a commercial ultrasound speckle tracking algorithm on tendon tissue2016In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 57, no 10, p. 1223-1229Article in journal (Refereed)
    Abstract [en]

    Background: Ultrasound speckle tracking offers a non-invasive way of studying strain in the free Achilles tendon where no anatomical landmarks are available for tracking. This provides new possibilities for studying injury mechanisms during sport activity and the effects of shoes, orthotic devices, and rehabilitation protocols on tendon biomechanics. Purpose: To investigate the feasibility of using a commercial ultrasound speckle tracking algorithm for assessing strain in tendon tissue. Material and Methods: A polyvinyl alcohol (PVA) phantom, three porcine tendons, and a human Achilles tendon were mounted in a materials testing machine and loaded to 4% peak strain. Ultrasound long-axis cine-loops of the samples were recorded. Speckle tracking analysis of axial strain was performed using a commercial speckle tracking software. Estimated strain was then compared to reference strain known from the materials testing machine. Two frame rates and two region of interest (ROI) sizes were evaluated. Results: Best agreement between estimated strain and reference strain was found in the PVA phantom (absolute error in peak strain: 0.21 +/- 0.08%). The absolute error in peak strain varied between 0.72 +/- 0.65% and 10.64 +/- 3.40% in the different tendon samples. Strain determined with a frame rate of 39.4Hz had lower errors than 78.6Hz as was the case with a 22mm compared to an 11mm ROI. Conclusion: Errors in peak strain estimation showed high variability between tendon samples and were large in relation to strain levels previously described in the Achilles tendon.

  • 53.
    Gasser, T. Christian
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Biomechanics.
    Martufi, Giampaolo
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Biomechanics.
    Auer, M.
    Folkesson, M.
    Swedenborg, J.
    Micromechanical Characterization of Intra-luminal Thrombus Tissue from Abdominal Aortic Aneurysms2010In: Annals of Biomedical Engineering, ISSN 0090-6964, E-ISSN 1573-9686, Vol. 38, no 2, p. 371-379Article in journal (Refereed)
    Abstract [en]

    The reliable assessment of Abdominal Aortic Aneurysm rupture risk is critically important in reducing related mortality without unnecessarily increasing the rate of elective repair. Intra-luminal thrombus (ILT) has multiple biomechanical and biochemical impacts on the underlying aneurysm wall and thrombus failure might be linked to aneurysm rupture. Histological slices from 7 ILTs were analyzed using a sequence of automatic image processing and feature analyzing steps. Derived microstructural data was used to define Representative Volume Elements (RVE), which in turn allowed the estimation of microscopic material properties using the non-linear Finite Element Method. ILT tissue exhibited complex microstructural arrangement with larger pores in the abluminal layer than in the luminal layer. The microstructure was isotropic in the abluminal layer, whereas pores started to orient along the circumferential direction towards the luminal site. ILT's macroscopic (reversible) deformability was supported by large pores in the microstructure and the inhomogeneous structure explains in part the radially changing macroscopic constitutive properties of ILT. Its microscopic properties decreased just slightly from the luminal to the abluminal layer. The present study provided novel microstructural and micromechanical data of ILT tissue, which is critically important to further explore the role of the ILT in aneurysm rupture. Data provided in this study allow an integration of structural information from medical imaging for example, to estimate ILT's macroscopic mechanical properties.

  • 54.
    Gatty, Hithesh K.
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Leijonmarck, Simon
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Antelius, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Roxhed, Niclas
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    An amperometric nitric oxide sensor with fast response and ppb-level concentration detection relevant to asthma monitoring2015In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 209, p. 639-644Article in journal (Refereed)
    Abstract [en]

    A MEMS-based amperometric nitric oxide (NO) gas sensor is reported in this paper. The sensor is designed to detect NO gas for the purpose of asthma monitoring. The unique property of this sensor lies in the combination of a microporous high-surface area electrode that is coated with Nafion (TM), together with a liquid electrolyte. The sensor is able to detect gas concentrations of the order of parts-per-billion (ppb) and has a measured NO sensitivity of 0.045 nA/ppb and an operating range between 25 and 65% relative humidity. The settling time of the sensor is measured to 8s. The selectivity to interfering gases such as ammonia (NH3) and carbon monoxide (CO) was high when placing an activated carbon fiber filter above the sensor. The ppb-level detection capability of this sensor combined with its relatively fast response, high selectivity to CO and NH3 makes the sensor potentially applicable in gas monitoring for asthma detection.

  • 55.
    Gatty, Hithesh K.
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Stemme, Göran
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Roxhed, Niclas
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    A Miniaturized Amperometric Hydrogen Sulfide Sensor Applicable for Bad Breath Monitoring2018In: Micromachines, E-ISSN 2072-666X, Vol. 9, no 12, article id 612Article in journal (Refereed)
    Abstract [en]

    Bad breath or halitosis affects a majority of the population from time to time, causing personal discomfort and social embarrassment. Here, we report on a miniaturized, microelectromechanical systems (MEMS)-based, amperometric hydrogen sulfide (H2S) sensor that potentially allows bad breath quantification through a small handheld device. The sensor is designed to detect H2S gas in the order of parts-per-billion (ppb) and has a measured sensitivity of 0.65 nA/ppb with a response time of 21 s. The sensor was found to be selective to NO and NH3 gases, which are normally present in the oral breath of adults. The ppb-level detection capability of the integrated sensor, combined with its relatively fast response and high sensitivity to H2S, makes the sensor potentially applicable for oral breath monitoring.

  • 56.
    Govind, Satish C.
    et al.
    BMJ Heart Center, Bangalore, India.
    Brodin, Lars-Åke
    Department of Clinical Physiology, Karolinska University Hospital at Huddinge, Stockholm, Sweden.
    Nowak, J.
    Department of Clinical Physiology, Karolinska University Hospital at Huddinge, Stockholm, Sweden.
    Quintana, M.
    Department of Clinical Physiology, Karolinska University Hospital at Huddinge, Stockholm, Sweden.
    Raumina, S.
    Department of Clinical Physiology, Karolinska University Hospital at Huddinge, Stockholm, Sweden.
    Ramesh, S.S.
    BMJ Heart Center, Bangalore, India.
    Keshava, R.
    BMJ Heart Center, Bangalore, India.
    Saha, S.
    Department of Clinical Physiology, Karolinska University Hospital at Huddinge, Stockholm, Sweden.
    Isolated Type 2 Diabetes mellitus Causes Myocardial Dysfunction That Becomes Worse in the Presence of Cardiovascular Diseases: Results of the Myocardial Doppler in Diabetes (MYDID): Study 12005In: Cardiology, ISSN 0008-6312, E-ISSN 1421-9751, Vol. 103, no 4, p. 189-195Article in journal (Refereed)
    Abstract [en]

    Aims: Patients with type 2 diabetes mellitus (DM) often suffer disproportionately and have a worse outcome when burdened with cardiovascular complications compared with those without DM. A specific heart muscle disease reportedly caused by DM per se may explain this. We sought to investigate whether an echo Doppler diagnosis of such a myocardial disease is clinically relevant in DM with or without coexistent coronary artery disease (CAD) and/or hypertension ( HTN). Subjects and Methods: Two hundred subjects (127 males, 73 females, 56 +/- 10 years) including controls (n=23), patients with HTN (n=20), CAD (n=35), uncomplicated DM (n=59), DM+HTN (n=27), DM+ CAD (n=16) and DM+CAD+HTN (n=20) underwent tissue Doppler-enhanced dobutamine stress echocardiography. Myocardial function was assessed by measuring left ventricular myocardial peak systolic velocity (PSV) and early diastolic velocity at rest and during peak stress, besides measurements of standard Doppler variables. Results: Average left ventricular PSV at rest was significantly lower in CAD (4.7 +/- 1.5) compared with controls (5.7 center dot +/- 1.2) and in DM+CAD+HTN (4.6 +/- 1.4) compared with DM (5.6 +/- 1.3; all p < 0.05). During peak stress, lower PSV persisted in CAD (9.5 +/- 3.1) and DM+CAD+HTN (8.1 +/- 2.7), while appearing de novo in DM (11.3 +/- 2.6) and HTN (11.0 +/- 2.3) unlike in the controls (12.5 +/- 2.5; all p < 0.001). When pooled together, DM subjects with CAD and/or HTN or both had significantly lower PSV (9.1 +/- 2.7) than those without (10.0 +/- 2.8; p < 0.001). Early diastolic velocity response was equally lower in both groups compared with the controls. Conclusion: The results suggest that dobutamine stress unmasks myocardial functional disturbances caused by uncomplicated DM. The discrete disturbances become quantitatively more pronounced in the presence of coexistent cardiovascular diseases.

  • 57.
    Govind, Satish C.
    et al.
    Bhagwan Mahavir Jain Heart Center, Bangalore, India.
    Roumina, S.
    Karolinska University Hospital at Huddinge, Stockholm, Sweden.
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical Engineering.
    Nowak, J.
    Karolinska University Hospital at Huddinge, Stockholm, Sweden.
    Ramesh, S. S.
    Bhagwan Mahavir Jain Heart Center, Bangalore, India.
    Saha, S. K.
    Karolinska University Hospital at Huddinge, Stockholm, Sweden.
    Differing myocardial response to a single session of hemodialysis in end-stage renal disease with and without type 2 diabetes mellitus and coronary artery disease2006In: Cardiovascular Ultrasound, E-ISSN 1476-7120, Vol. 4, no 9Article in journal (Refereed)
    Abstract [en]

    Background: Though hemodialysis (HD) acutely improves cardiac function, the impact of background diseases like coronary artery disease (CAD) and Type 2 diabetes (DM) in the setting of end-stage renal disease (ESRD) is not known. Tissue velocity echocardiography (TVE) offers a fast choice to follow changes in myocardial function after HD in ESRD with concomitant DM and/or CAD. Methods: 46 subjects (17 with ESRD, Group 1; 15 with DM, Group 2; 14 with DM+CAD, Group 3) underwent standard and TVE prior to and shortly after HD. Besides standard Doppler variables, regional myocardial systolic and diastolic velocities, as well as systolic strain rate were post processed. Results: Compared with pre-HD, post-HD body weight (kg) significantly decreased in all the three groups (51 ± 9 vs. 48 ± 8, 62 ± 10 vs.59 ± 10, and 61 ± 9 vs. 58 ± 9 respectively; all p < 0.01). Left ventricular end diastolic dimensions (mm) also decreased post- HD (46 ± 5 vs. 42 ± 7, 53 ± 7 vs. 50 ± 7, 51 ± 7 vs. 47 ± 8 respectively; all p < 0.01). Regional longitudinal peak systolic velocity in septum (cm/s) significantly increased post-HD in Group 1(5.7 ± 1.6 vs. 7.2 ± 2.3; p < 0.001) while remained unchanged in the other two groups. Similar trends were noted in other left ventricular walls. When the myocardial velocities (cm/s) were computed globally, the improvement was seen only in Group 1 (6.3 ± 1.5 vs. 7.9 ± 2.0; p < 0.001). Global early regional diastolic velocity (cm/s) improved in Group 1, remained unchanged in Group 2, while significantly decreased in Group 3(-5.9 ± 1.3 vs. -4.1 ± 1.8; p < 0.01). Global systolic strain rate (1/sec) increased in the first 2 Groups but remained unchanged (-0.87 ± 0.4 vs. -0.94 ± 0.3; p = ns) in Group 3. Conclusion: A single HD session improves LV function only in ESRD without coexistent DM and/or CAD. The present data suggest that not only dialysis-dependent changes in loading conditions but also co-existent background diseases determine the myocardial response to HD.

  • 58.
    Govind, Satish C.
    et al.
    Department of Clinical Physiology, Karolinska Institute, Karolinska University Hospital, Huddinge, Stockholm, Sweden.
    Saha, S.
    Department of Clinical Physiology, Karolinska Institute, Karolinska University Hospital, Huddinge, Stockholm, Sweden.
    Brodin, Lars-Åke
    Department of Clinical Physiology, Karolinska Institute, Karolinska University Hospital, Huddinge.
    Ramesh, S. S.
    BMJ Heart Center, Bangalore, India.
    Arvind, S. R.
    BMJ Heart Center, Bangalore, India.
    Quintana, M.
    Department of Clinical Physiology, Karolinska Institute, Karolinska University Hospital, Huddinge, Stockholm, Sweden.
    Impaired Myocardial Functional Reserve in Hypertension and Diabetes Mellitus Without Coronary Artery Disease: Searching for the Possible Link With Congestive Heart Failure in the Myocardial Doppler in Diabetes (MYDID) Study II2006In: American Journal of Hypertension, ISSN 0895-7061, E-ISSN 1941-7225, Vol. 19, no 8, p. 851-857Article in journal (Refereed)
    Abstract [en]

    Background: Although the impact of type 2 diabetes mellitus (DM) and hypertension (HTN) on myocardial function has recently been studied using tissue Doppler echocardiography (TDE), the independent role of both conditions, and the influence of other risk factors on myocardial function has not been completely defined, particularly in absence of coronary artery disease (CAD). The aim of this study was to assess the myocardial functional reserve in patients with DM or HTN with apparently normal left ventricular (LV) systolic function.

    Methods: Standard and dobutamine stress echocardiography using TDE was performed in 128 subjects: 59 had DM, 20 had HTN, 27 had both DM and HTN (HTN + DM), and 22 subjects were controls (C). Subjects with known CAD and depressed LV function were excluded. In addition, standard two-dimensional and Doppler measurements, LV regional peak systolic (PSV), early (E') and late (A') diastolic velocities, strain (S%) and strain rate (SR), were assessed at rest and peak stress.

    Results: The LV mass did not differ, although relative wall thickness was significantly higher in subjects with HTN + DM and HTN. The PSV did not differ at rest but was lowest in subjects with HTN + DM at peak stress. The E' wave velocity was significantly lower in subjects with HTN + DM both at rest and during peak stress, as were S% and SR.

    Conclusions: The addition of DM to HTN has a negative effect on LV systolic and diastolic functions. A depressed myocardial functional reserve might be postulated as one of the pathophysiologic mechanisms for the excessive occurrence of congestive heart failure in patients with DM or HTN.

  • 59.
    Grannerud, Malena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Identification of Potential Sources of Measurement Errors in an Isokinetic Dynamometer: Reliability Analysis of Shoulder Abduction and Flexion Data2022Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The evaluation of shoulder abduction and flexion strength is important in the rehabilitation after rotator cuff tear. The purpose of this work is to assess the intra and inter-rater reliability of measurement data from an isokinetic dynamometer used to evaluate shoulder abduction and flexion strength, with the aim to identify sources of measurement errors and suggest improvements. The measurement data was collected by a research group at Karolinska Institute and contained load and torque data from thirteen healthy subjects in the ages of 25 to 87 years. The measurements were carried out on two occasions, one week apart. Systematic differences between occasions are analyzed using the Shapiro Wilk test, the paired t-test, and Wilcoxon signed rank test. The agreement of the measurements is analyzed quantitatively using the coefficient of variation and the Bland Altman plot, and quantitively, using the intraclass correlation coefficient. A significant systematic difference in shoulder abduction and flexion load measurements was found, and the recommendation to prevent this is that components should be calibrated in a standardized way. The measurements showed varying reliability within and between measurement occasions and that after familiarization with the isokinetic dynamometer, repeatability improved. The findings indicate a need of a standardized protocol for patient education and placement. Measurements from the position sensor contributed to more random torque values. To improve the repeatability in measurements from the position sensor, axis of rotation should be kept aligned. An increasing variability in measurements with increasing load and torque was found. The recommendation is to use a preload for patients using more force in the movement, to make sure a preset speed is not exceeded, which contributes to more reliable measurements. 

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  • 60.
    Gripentoft, Lou
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems.
    Isik, Zilan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems.
    EEG Signal Analysis in the Frequency Domain: An Examination of Abnormalities During the Gait Cycle2022Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Many people experience discomfort during movement when using a knee prosthesis. As a result, a study is being conducted to see if biomedical models can be used to produce an optimal prosthetic socket to reduce discomfort. This has previously been accomplished using pressure sensors embedded in the sleeve to measure leg pressure at various stages of the gait cycle. To gather more information, an EEG should be performed to find where discomfort occurs throughout a gait cycle. The purpose of the EEG is to perform measurements for a certain time during walking to then be able to analyze the signals that occur from the brain's motor cortex. The signal analysis is performed by applying the Fast Fourier transform to convert EEG data from the time domain to the frequency domain. By examining frequency differences, it is demonstrated that additional measurements with more individuals are required to ensure that the results reflect discomfort, and that the EEG is useful in the applied field of use.

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  • 61.
    Grishenkov, Dmitry
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging. Karolinska Institutet (KI), CLINTEC – Division of Medical Imaging and Technology.
    Contrast agent for early diagnostics and monitoring of progression of liver cancer (hepatocellular carcinoma)2013Conference paper (Refereed)
  • 62.
    Grishenkov, Dmitry
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Ultrasound. KTH, School of Technology and Health (STH), Medical Engineering.
    Diagnostic Power of Different Tissue Doppler Parameters during Ultrasound Cardio-Vascular Investigation2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The department of Medical Technology, where I have done Master thesis project, develops and researches new method and technique within areas where ultrasound can be used to obtain the image of anatomical structure, functional capabilities and to suggest required treatment.

    Nowadays cardio-vascular diseases, such as infarct, atherosclerosis and ischemic syndrome, are one of the most widespread diseases in the world that’s why timely detection, identification and treatment are so important.

    The Master of Science qualification report consists 3 major parts: Medico-biological part, Design and Research parts.

    In Medico-biological part has been analyzed anatomical and physiological structure of the heart, current status of echocardiography with comparing with other techniques, summary of ultrasound methods with list of parameters that can be achieved is presented.

    In Design part has been developed new graphical modality based on Delta-V pump model using vector based statistical analysis for identification patients with ischemia. Software algorithm for automatically determine characteristic points for state diagram written in MatLab has been developed and implemented.

    In Research part in the first task using commercially available software based on Principal Component Analysis collected data from the hospital patients has been studied, results proved hypothesis concerning time variables importance; in the second task graphical module has been examined using collected data from the hospital patients both normal and with different cardio-vascular disease, and the results show good detection power of the algorithm.

    At the end of the project presentation has been done and report has been published.

    This project has been done in collaboration with the biggest medical institute in Sweden – Karolinska Institute - and results will be used in medical practice in Karolinska University Hospital in Huddinge and for future scientific needs.

     

  • 63.
    Grishenkov, Dmitry
    KTH, School of Technology and Health (STH), Medical Engineering.
    Three modality contrast imaging using multi-functionalized microballoons2011Conference paper (Refereed)
    Abstract [en]

    In vivo multimodality imaging is a fast growing field in medical research and, although the achievements at clinical level of this diagnostic method are recent, it is already one of the most promising approaches in the diagnosis of diseases in many research addressed medical centres. At present in this area, the USA plays the protagonist role as a result of the amount of resources engaged in the arena in the last decade. Both government and private companies agree, when considering the potential of this approach, that it is one of the foremost medical advancements as it will lead to early diagnosis of diseases with high impact on the societies of western countries. Multimodality imaging is currently viewed as a simple and powerful integration of two or more imaging methods (e.g. PET-CT). 3MICRON is an ambitious project which gathers some of the most advanced European medical and technical institutions together to address the design of new strategies in diagnostics, and to push the potential of medical imaging beyond the state-of-the-art. The multimodality approaches are supported by a class of next-generation micro/nanodevices called microballoons. These subsystems are able to implement the function of an ultrasound contrast agent with other imaging methods (SPECT, MRI). In the future, they may act as a minimally invasive drug delivery method and hyperthermia device. In 3MICRON, this multi-functional device will be tested in vitro and in vivo in order to assess bioclearance and cytoxicity effects toward high impact diseases, e.g. cardiovascular and inflammation pathologies. Finally, selected types of microballoons will undergo pre-clinical screening for a consolidated assessment of the “bench-to-bed” pathway for these new microdevices.

  • 64.
    Grishenkov, Dmitry
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical Engineering.
    Brismar, Torkel B.
    CLINTEC, Department of Radiology, Karolinska University Hospital.
    Paradossi, Gaio
    Dipartimento di Chimica, Università di Roma Tor Vergata.
    On comparison between polymer- and phospholipid-shelled microbubbles for contrast-enhanced ultrasound measurements of capillary microcirculation.2011In: Proceedings of the 34th Scandinavian Symposium on Physical Acoustics / [ed] Rolf J. Korneliussen, 2011Conference paper (Refereed)
    Abstract [en]

    The focus of contrast-enhanced ultrasound research has developed beyond visualizing the blood circulation to new areas such as perfusion and molecular imaging, drug and gene therapy. This work compares the application of polymer- and phospholipid-shelled ultrasound contrast agents (UCAs) employed for characterization of the capillary microcirculation. To quantify microcirculation destruction/replenishment technique with varied time intervals between destructive and monitoring pulses is used. The dependence of the peak-to-peak amplitude of backscattered wave versus pulse interval is fitted with an exponential function of the time y=A(1-exp(-βt)) , where A represents capillary volume and the time constant β represents velocity of the flow. Working under assumption that backscattered signal is linearly proportional to the microbubble concentration, for both types of the UCAs it is observed that capillary volume, A, is in linearly relationship with the concentration, and the flow velocity, β, remain unchanged. Using 500 µm diameter microtube as a vessel phantom a delay of about 0.25 s in evaluation of the perfusion characteristics is found for the phospholipid-shelled UCA, while polymer-shelled UCA provide response immediately. In conclusion, these results suggest that the novel polymer-shelled microbubbles have a potential to be used for perfusion evaluation.

  • 65.
    Grishenkov, Dmitry
    et al.
    Karolinska Institutet (KI), CLINTEC – Division of Medical Imaging and Technology.
    Gonon, Adrian
    Paradossi, Gaio
    Diapartimento di Chimica, Università di Roma Tor Vergata.
    Janerot Sjöberg, Birgitta
    CLINTEC, Department of Medical Imaging and Technology, Karolinska Institute.
    Ultrasound contrast agent loaded with nitric oxide as a theranostic microdevise for myocardial ischemia2013Conference paper (Refereed)
    Abstract [en]

    Cardiovascular disease (CVD) accounts for 1/3 of total global deaths worldwide. The most widespread CVD is ischemic heart disease. It is the leading cause of death in both genders, equally diagnosed in developed and developing countries withmortality exponentially increasing with age. Efforts of healthcare system should be primary focused on prevention, timely detection, efficient differentiation and instant treatment of the disease.

  • 66.
    Grishenkov, Dmitry
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Ultrasound.
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Brismar, Torkel B.
    Karolinska University Hospital.
    Paradossi, Gaio
    Università di Roma Tor Vergata.
    Acoustic properties of polymer-shelled ultrasound contrast agents. Bulk volume vs. microcapillary2009In: 16th International Congress on Sound and Vibration 2009, ICSV 2009, Krakow, 2009, p. 2515-2522Conference paper (Refereed)
    Abstract [en]

    The focus of contrast-enhanced ultrasound research has developed beyond detecting the blood pool to new areas such as perfusion imaging, drug and gene therapy, and targeted imaging. Polymer-shelled microbubbles are proposed as a new generation of ultrasound contrast agents (UCAs) which fulfil the requirements of these applications. With a shelf-life of several months and possibility to conjugate pharmacological molecules to their surface, these UCAs will allow not only to enhance the contrast of ultrasound images, but also to function as carriers of drugs to be delivered locally. In this study, the results of an experimental investigation of three types of UCAs stabilized by thick poly vinyl alcohol (PVA) shell are presented. These UCAs are synthesized from a PVA aqueous solution under varied pH values and temperature. The UCAs differ from each other in their average diameter, shell thickness and polydispersity. Knowledge of the peak negative pressure at which the solid shell fractures is paramount for a proper use of UCAs. Therefore, the dependence of this quantity on temperature and number of cycles in the incident pulse is examined. Much of the blood volume resides in the microcirculation, with capillaries playing a particularly important role in patho-physiology and drug delivery. In this sense in vitro characterization of the UCAs oscillation was moved from bulk volume to the capillary scale, where tissue-bubble interaction takes place. The main conclusion to be drawn from these results is that the shell of the UCAs begin to fracture at values of mechanical index (MI) approved for clinical applications. The fatigue, i.e. the accumulation of damage within the shell of the UCAs, is found to play an important role in fracturing the shell. Finally adhesion of the UCAs to the elastic wall is studied and correlated with estimates of the shell’s visco-elastic constants. Open questions arising from this comparison are briefly discussed.

  • 67.
    Grishenkov, Dmitry
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical Engineering.
    Brismar, Torkel B.
    CLINTEC, Department of Radiology, Karolinska Institutet.
    Paradossi, Gaio
    Dipartimento di Chimica, THE UNIVERSITY OF ROME.
    In vitro contrast-enhanced ultrasound measurements of capillary microcirculation: Comparison between polymer- and phospholipid-shelled microbubbles2011In: Ultrasonics, ISSN 0041-624X, E-ISSN 1874-9968, Vol. 51, no 1, p. 40-48Article in journal (Refereed)
    Abstract [en]

    The focus of contrast-enhanced ultrasound research has developed beyond visualizing the blood pool and its flow to new areas such as perfusion imaging, drug and gene therapy, and targeted imaging. In this work comparison between the application of polymer- and phospholipid-shelled ultrasound contrast agents (UCAs) for characterization of the capillary microcirculation is reported. All experiments are carried out using a microtube as a vessel phantom. The first set of experiments evaluates the optimal concentration level where backscattered signal from microbubbles depends on concentration linearly. For the polymer-shelled UCAs the optimal concentration level is reached at a value of about 2 x 10(4) MB/ml, whereas for the phospholipid-shelled UCAs the optimal level is found at about 1 x 10(5) MB/ml.

    Despite the fact that the polymer shell occupies 30% of the radius of microbubble, compared to 0.2% of the phospholipid-shelled bubble, approximately 5-fold lower concentration of the polymer UCA is needed for investigation compared to phospholipid-shelled analogues. In the second set of experiments, destruction/replenishment method with varied time intervals ranging from 2 ms to 3 s between destructive and monitoring pulses is employed. The dependence of the peak-to-peak amplitude of backscattered wave versus pulse interval is fitted with an exponential function of the time gamma = A( 1 - exp(-beta t)) where A represents capillary volume and the time constant beta represents velocity of the flow. Taking into account that backscattered signal is linearly proportional to the microbubble concentration, for both types of the UCAs it is observed that capillary volume is linearly proportional to the concentration of the microbubbles, but the estimation of the flow velocity is not affected by the change of the concentration. Using the single capillary model, for the phospholipid-shelled UCA a delay of about 0.2-0.3 s in evaluation of the perfusion characteristics is found while polymer-shelled UCA provide response immediately. The latter at the concentration lower than 3.6 x 10(5) MB/ml have no statistically significant delay (p < 0.01), do not cause any attenuation of the backscattered signal or saturation of the receiving part of the system. In conclusion, these results suggest that the novel polymer-shelled microbubbles have a potential to be used for perfusion evaluation.

  • 68.
    Grishenkov, Dmitry
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Kothapalli, Veeravenkata S.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Gonon, Adrian
    Karolinska University Hospital, Huddinge, Sweden .
    Janerot Sjöberg, Birgitta
    CLINTEC, Department of Medical Imaging and Technology, Karolinska Institute.
    Ultrasound contrast agent loaded with nitric oxide as a theranostic microdevise for myocardial ischemia2013In: European Heart Journal Cardiovascular Imaging: Abstracts of EUROECHO 2013 The Seventeenth Annual Meeting of the European Association of Echocardiography, 2013Conference paper (Refereed)
    Abstract [en]

    Cardiovascular disease (CVD) accounts for 1/3 of total global deaths worldwide. The most widespread CVD is ischemic heart disease. It is the leading cause of death in both genders, equally diagnosed in developed and developing countries with mortality exponentially increasing with age. Efforts of healthcare system should be primary focused on prevention, timely detection, efficient differentiation and instant treatment of the disease.

  • 69.
    Grishenkov, Dmitry
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Paradossi, Gaio
    Diapartimento di Chimica, Università di Roma Tor Vergata.
    Assessment of ultrasound-induced fracture of polymer-shelled ultrasound contrast agents using superharmonic technique2012Conference paper (Refereed)
    Abstract [en]

    Ultrasound imaging techniques can be greatly improved by the use of ultrasound contrast agents. Knowledge of the peak negative pressure at which contrast agents fracture is paramount for the imaging application as well as for local drug delivery. Gasholdning microbubbles encapsulated into biocompatible poly vinyl alcohol shells are of particular interest for their enhanced shelf life and demonstratedchemical versatility. A gas core allows microbubbles to efficiently scatter ultrasound waves. In vitro ultrasound tests showed a sufficient enhancement of the backscattered power (25±1 dB), comparable to the soft tissue attenuation coefficients (0.8±0.04 dB/cm MHz) and phase velocities (1519±2 m/s). At temperature values between 24 and 37 °C the monotonic increase of the attenuation and phase velocity with frequency indicates that thick-shelled microbubbles do not resonate in a typical medical ultrasound frequency range of 1-15 MHz. In fact, they work as an amplifier of the incident acoustic wave. The novel approach based on detection of superharmonics (3f and 4f) is proposed for assessment of the fracture pressure threshold, Pthr. In vitro tests suggests that fatigue, i.e. accumulation of damage within the shell, is the major physical mechanism responsible for the fracturing process. It has been observed that there is a decrease of Pthr from 1.15±0.09 MPa to 0.9±0.05 MPa when the number of cycles in the pulse, N, increases from 6 to 12. It is worth noting that the reported pressure values are within clinically approved safety limits. The main conclusion to be drawn from our study is that superharmonic approach appears to be more sensitive in Pthr assessment than traditional second harmonic imaging. This claim is supported also by images acquired with a commercially available system, where contrast pulse sequencing technique, specific to third harmonic, is required for visualization of thick-shelled microbubbles.

  • 70.
    Grishenkov, Dmitry
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Ultrasound.
    Pecorari, Claudio
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Ultrasound.
    Brismar, Torkel B.
    Karolinska University Hospital.
    Paradossi, Gaio
    Università di Roma Tor Vergata.
    Characterization of Acoustic Properties of PVA-Shelled Ultrasound Contrast Agents2010In: Ultrasound Contrast Agents: Targeting And Processing Methods For Theranostics / [ed] G. Paradosi, P. Pellegretti, A. Trucco, Italia: Springer-Verlag , 2010, p. 99-108Chapter in book (Other academic)
    Abstract [en]

    This work examines the acoustic behavior of ultrasound contrast agents made of poly (vinyl alcohol) (PVA) shelled microbubbles manufactured at three different pH and temperature conditions. Backscattering amplitude, attenuation coefficient and phase velocity of ultrasonic waves propagating through suspensions of PVA contrast agents were measured at temperature values ranging between 24 oC and 37 oC in a frequency range from 3 MHz to 13 MHz.  A significant enhancement of the backscattering amplitude and displaying a weak dependence on temperature were observed.  Attenuation and phase velocity, on the other hand, showed higher sensitivity to temperature variations.  The dependence on system parameters such as the number of cycles, frequency, and exposure of the peak negative pressure, Pthr, at which ultrasound contrast agents fracture was also investigated.  The effects of temperature, blood, and, wherever data are available, of the dimension of the microbubbles on Pthr are also considered.  The large shell thickness notwithstanding, the results of this investigation show that at room temperature PVA contrast agents fracture at negative peak pressure values within the recommended safety limit.  Furthermore, Pthr decreases with increasing temperature, radius of the microbubbles, and number of cycles of the incident wave.  In conclusion, these results suggest that PVA-shelled microbubbles may offer a potentially viable system to be employed for both imaging and therapeutic purposes.

  • 71.
    Grishenkov, Dmitry
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Ultrasound.
    Pecorari, Claudio
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Ultrasound.
    Brismar, Torkel B.
    Karolinska University Hospital.
    Paradossi, Gaio
    Università di Roma Tor Vergata.
    On the acoustic properties of polymer-shell ultrasonic contrast agents.2008Conference paper (Other academic)
    Abstract [en]

    Polymer-shelled microbubbles have become the focus of intense research for their enhanced shelf life and demonstrated chemical versatility.  These are properties highly sought after in the ultrasonic contrast agents (UCAs) of the next generation, which will be engineered not only to enhance the contrast of ultrasound-based images, but also to function as carriers of drugs to be delivered locally.  Here, the results of an experimental investigation of three potentially new UCAs are presented.  These microbubbles are stabilized by thick poly (vinyl alcohol) shells.  These UCAs differ from each other in their dimensions and shell thickness (order of 0.5 microns).  Fundamental to their use as drug carrier is the knowledge of the pressure threshold at which the shell of these UCAs fractures.  Therefore, the dependence of this quantity on temperature, number of cycles of the incident pulse, nominal central frequency and pulse repetition frequency of the emitting transducer is examined.  The effect of using blood instead of deionized water is also considered.  The main conclusion to be drawn from these results is that their thick shell notwithstanding, these microbubbles begin to fracture at values of MI which can be acceptable in clinical applications.  This claim is supported also by images acquired by means of commercially available imaging systems.  Finally, these values of the pressure threshold are correlated with estimates of the shells’ visco-elastic constants obtained by fitting Church’s model to the frequency-dependent attenuation coefficient and phase velocity.  Open questions arising from this comparison are briefly discussed.

  • 72.
    Groth, Kristina
    et al.
    KTH, School of Computer Science and Communication (CSC), Human - Computer Interaction, MDI.
    Frykholm, Oscar
    KTH, School of Computer Science and Communication (CSC), Human - Computer Interaction, MDI.
    Segersvard, Ralf
    CLINTEC, Karolinska Institutet, Stockholm.
    Isaksson, Bengt
    CLINTEC, Karolinska Institutet, Stockholm.
    Permert, Johan
    CLINTEC, Karolinska Institutet, Stockholm.
    Efficiency in Treatment Discussions: A Field Study of Time Related Aspects in Multi-Disciplinary Team Meetings2009In: 2009 22ND IEEE INTERNATIONAL SYMPOSIUM ON COMPUTER-BASED MEDICAL SYSTEMS   , 2009, p. 88-95Conference paper (Refereed)
    Abstract [en]

    We present a field study of multi-disciplinary team meetings where decisions on treatment of patients with diseases in the upper part of the abdomen are made. These meetings are important for knowledge dissemination and learning. We have studied how different time related aspects affect the efficiency during these meetings. Time is relevant because several physicians attend these meetings, and they have tight schedules as it is. Our analysis focuses on the conversation during the team meetings, and on how aspects such as indistinct discussions, lack of relevant competence and information, and the structuring of medical information affect time efficiency.

  • 73. Gullstrand, Lennart
    et al.
    Halvorsen, Kjartan
    Tinmark, Fredrik
    Eriksson, Martin
    KTH, School of Technology and Health (STH), Medical Engineering.
    Nilsson, Johnny
    Measurements of vertical displacement in running, a methodological comparison2009In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 30, no 1, p. 71-75Article in journal (Refereed)
    Abstract [en]

    The aim was (1) to evaluate measurements of vertical displacements (V-disp) of a single point on sacrum as an estimate of the whole body centre of mass (CoM) V-disp during treadmill running and (2) to compare three methods for measuring this single point. These methods were based on a position transducer(PT), accelerometers (AMs) and an optoelectronic motion capture system. Criterion method was V-disp of the whole body CoM measured with the motion capture system. Thirteen subjects ran at 10, 12, 14, 16. 18, 20 and 22 km h(-1) with synchronous recordings with the three methods. Four measurements of the (V-disp) were derived: (1) V-disp of CoM calculated from a segment model consisting of 13 segments tracked with 36 reflective markets, (2) V-disp of the sacrum recorded with the PT, (3) V-disp of the sacrum Calculated from the AM, and (4) V-disp of the sacrum calculated as the mid point of two reflective markets (sacrum marker, SM) attached at the level of the sacral bone. The systematic discrepancy between the Measurements of sacrum V-disp and CoM V-disp varied between 0 and 1.5 mm and decreased with increasing running velocity and decreasing step duration. PT and SM measurements showed strong correlation, whereas the AM showed a variability increasing with velocity. The random discrepancy within each Subject was 7 mm for all three methods. In conclusion single-point recordings of the sacrum V-disp may be used to monitor changes in V-disp of CoM during treadmill running.

  • 74.
    Guo, Maoxiang
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Hernández-Neuta, Iván
    Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Sweden.
    Madaboosi, Narayanan
    Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Sweden.
    Nilsson, Mats
    Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Sweden.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Cross-membrane electrical detection of DNA2017In: Proceedings 21st International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2017, The Chemical and Biological Microsystems Society (CBMS) , 2017, , p. 44-45Conference paper (Refereed)
    Abstract [en]

    We introduce out-of-plane metallic nanowire formation on DNA templates, which are stretched through a porous membrane by applying a receding meniscus interface. We demonstrate the direct electrical detection of DNA using these gold nanowire bridges between the membrane’s opposite surfaces. Such a simple electrical readout can be extended for biosensor applications, thanks to the high specificity and multiplexing offered by Rolling Circle Amplification (RCA).

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  • 75.
    Halvorsen, Kjartan
    KTH, School of Technology and Health (STH), Medical Engineering.
    Comments on "The equations of motion for a standing human reveal three mechanisms for balance" (A. Hof, Vol. 40, pp. 451-457)2010In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 43, no 16, p. 3244-3247Article in journal (Refereed)
  • 76.
    Hamid Muhammed, Hamed
    KTH, School of Technology and Health (STH), Health Systems Engineering.
    Image Enhancement And Reduction Of Radiation Dose For Panoramic Dental X-Ray Imaging2013In: Swedish Medical Engineering Conference 2013, Medicinteknikdagarna 2013, 2013Conference paper (Other academic)
    Abstract [en]

    1.  Background Reducing the X-ray dose too much produces images with low quality; Noisy, blurred, faded, under exposed. The approach used in this work aims at enhancing image quality by using advanced  automatic image processing algorithms.

    2.  Purpose To minimize X-ray dose exposure during panoramic dental X-ray imaging, in addition to automatically enhancing the acquired X-ray images to achieve high quality images that can be viewed using ordinary monitors.

    3.  Method An automatic, adaptive image enhancement algorithm was developed and implemented on multi-core CPU as well as GPU to achieve real time performance.

    4.  ResultsThe method was tested on panoramic dental X-ray images acquired with varying radiation dose. The results were promising and indicated the possibility of obtaining diagnostically usable images using a reduced dose by 50%. A group of ten dentists and specialists evaluated the resulted images. Figure (1) shows a comparison between an enhanced panoramic dental X-ray acquired with reduced dose by 50% and an original (unprocessed) panoramic dental X-ray acquired with a standard dose.

    5.  Discussion and conclusionsThis study shows the possibility to achieve a number of goals that can lead to better patient safety and better healthcare in general, such as:Minimized X-ray dose to the patient, which can lead to reduced risk of physical damage (e.g. cancer) and psycological consequences (e.g. stress).Better image quality which can lead to better, faster and more accurate and confident diagnostic.The resulted enhanced images can be automatically produced without any noticeable waiting time and viewed using any ordinary monitor (LCD/LED TV or computer screens) without any need for any expensive/exclusive high-dynamic-range displays.

  • 77.
    Hamid Muhammed, Hamed
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering.
    Moustafa, Ahmed M. Nasr
    KTH, School of Technology and Health (STH), Health Systems Engineering.
    Hassan, Moustapha
    Karolinska University Hospital Huddinge, Stockholm, SWEDEN.
    Skin Cancer Detection Using Temperature Variation Analysis2013In: Engineering, ISSN 1947-394X, Vol. 5, no 10BArticle in journal (Refereed)
    Abstract [en]

    In the medical field, new technologies are incorporated for the sole purpose of enhancing the quality of life for the patients and even for the normal healthy people. Infrared technology is one of the technologies that have some applications in both the medical and biological fields. In this work, the thermal infrared (IR) measurement is used to investigate the potential of skin cancer detection. IR enjoys non-invasive and non-contact advantages as well as favorable cost, apparently. It is also very well developed regarding the technological and methodological aspects. IR per se is an electro-metric radiation that all objects emit when their temperature is above the absolute zero. And the human body is not different in this regard. The IR range extends, ideally, to cover wavelengths from 800 nanometer to few hundred micrometer. Cancer, in modern life, has grown tangibly due to many factors, such as life expectancies increase, personal habits and ultraviolet radiation exposures among others. Moreover, the significant enhancement of technologies has helped identifying more types of cancers than before. The sole purpose of this work is to investigate further IR technology methods and applications not yet matured in skin cancer detection to enhance the detection ability with higher safety level.

  • 78.
    Hamid Muhammed, Hamed
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering.
    Moustafa, A.N.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Hassan, Moustapha
    Department of Laboratory Medicine, Karolinska University Hospital.
    Temperaturvariationsanalys för hudcancerscreening, Poster, Barncancerfondens tredje konferens2013In: Barncancerfondens tredje konferens: Medicinsk Teknik för Barn med Cancer, 2013Conference paper (Other academic)
    Abstract [sv]

    Den här studien visar att det är möjligt att detektera tydliga temperaturskillnader mellan cancervävnad och frisk vävnad. Detta kan vara ett resultat av både angiogenes (processen som leder till nybildning av blodkärl från de minsta befintliga blodkärl) och ökad ämnesomsättning hos cancerceller (medan cancertumörer formas) jämfört med friska normala celler, som ändrar och ökar intensiteten av den termiska IR-strålningen inom cancervävnads områden. Temperaturförändringarna detekterades genom mätningar av termisk IR-strålning inom våglängdsområdet 8-14 μm. Intensiva experiment utfördes på möss med hudcancer. Cancerområdet hade i genomsitt 0.3 – 0.5 °C högre temperatur än de friska grannområdena. Både kvalitativa och kvantitativa statistiska metoder användes för att analysera dessa mätningar. Analysresultaten verifierar användbarheten av att mäta termisk IR-strålning för att kunna detektera hudcancerområden.

  • 79.
    Hamid Muhammed, Hamed
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering.
    Raghavendra, Jammalamadaka
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Optomyografi (OMG): Ny teknik för muskelaktivitets mätning2015In: Abstract Proceedings of Medicinteknik dagarna 2015, 2015Conference paper (Other academic)
    Abstract [sv]

    Introduktion / Mål

    Den nya tekniken är effektivare och har inte de brister som de existerande teknikerna (elektromyografi EMG och mekanomyografi MMG) lider av, exempelvis, lågt signal till brus förhållande (SNR), interferens med andra biosignaler, interferens med externa signaler från omgivningen, påverkas av hudegenskaperna, komplicerad installation och kalibrering, kan inte användas vid extrema förhållanden, kan inte användas i rymden eller under vatten. Den nya tekniken används av:

    *Idrottare: för att optimera träningen.

    *Patienter och handikappade personer som lider av rörelsestörningar, svaga händer, amputerade händer, rygg eller nackskador.

    *Astronauter: för människa-dator interaktion och robotstyrning.

    Metod

    Den nya tekniken använder fotoelektriska sensorer som mäter reflekterade närainfraröda strålar från hudytan. Den reflekterade signalen varierar då topografiska förändringar, på landskapet som formas av hudytan, sker. Nästan inga bio- eller omgivande signaler interfererar med närainfraröda strålar. Hudens kemiska och fysiska egenskaper påverkar inte heller mätsignalernas kvalitet. Därför registreras signaler av hög SNR. Ytterligare fördelar med den nya tekniken är att den är kostnadseffektiv, mobil, användarvänlig, icke-invasiv och riskfri. Ett armband med två sensorer används för att mäta kontinuerliga tidssignaler när försökspersonen utför ett antal handrörelser.

    Resultat

    Olika handrörelser producerar olika signaler som mäts med hjälp av ett oscilloskop. Varje rörelse ger två signaler eller ett signalpar som skiljer sig från de signalpar som produceras av andra handrörelser.

    Sammanfattning

    Fotoelektriska sensorer används för att mäta reflekterade närainfraröda strålar från huden. Olika muskelaktiviteter och rörelser förändrar topografin av landskapet som formas av hudytan. Miniatyr lysdiod-sensor par byggs in i kläder för att mäta och analysera muskelaktivitet och rörelse. Mätvärdena skickas trådlöst till mobilen för att analyseras och ge återkoppling i realtid för att varna och optimera tränings eller rehabiliterings aktiviteterna.

  • 80.
    Hamid Muhammed, Hamed
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering.
    Raghavendra, Jammalamadaka
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Optomyography (OMG): A Novel Technique for the Detection of Muscle Surface Displacement Using Photoelectric Sensors2015In: Measurements - Proceedings of the 10th International Conference on Bioelectromagnetism, International Society for Bioelectromagnetism, 2015, Vol. 10Conference paper (Refereed)
    Abstract [en]

    Several techniques have been introduced for detecting, measuring, processing and analyzing the signals generated during muscular activities. With the development of more advanced technical solutions, the measurement and analysis of these signals help not only to understand the medical abnormalities and characterization of muscle activities but also to develop human machine interfaces of higher efficiency. In this work, a novel technique to detect and measure the displacement caused on the surface of the skin due to muscle activities was introduced and developed using near-infrared photoelectric sensors. The new technique was coined as OptoMyoGraphy (OMG). In order to evaluate the new technique, real-time pairs of signals were registered using two photoelectric sensors measuring near-infrared rays reflected on the forearm while moving the hand to make a number of different gestures. Different pairs of signals, changing over time and showing repeated patterns while repeating the same hand gesture, were measured for different hand gesture. The signal to noise ratio (SNR) of these signals was good enough to be able to differentiate among the pairs of signals which correspond to different hand gestures using visual inspection.

  • 81.
    Hauser, Janosch
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Dale, Matilda
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Affinity Proteomics.
    Schwenk, Jochen M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Affinity Proteomics.
    Stemme, Göran
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Fredolini, Claudia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Affinity Proteomics.
    Roxhed, Niclas
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    On-Chip Assay for Home-Sampling, Mail-Based Shipping and Centralized Laboratory Readout2021In: MicroTAS 2021: 25th International Conference on Miniaturized Systems for Chemistry and Life Sciences, Chemical and Biological Microsystems Society , 2021, p. 807-808Conference paper (Refereed)
    Abstract [en]

    On-chip immunoassays have great potential to accelerate point-of-care (POC) testing. However, most attempts require either impractical readout equipment or are outperformed by the sensitivity, reliability and affordability offered by centralized laboratories. Here, we present a capillary-driven microfluidic device that unites the best of two worlds: Bead-based analyte isolation at the POC, where analyte drying enables simple mail-based shipping, combined with the powerful capabilities of centralized laboratories. Using C-reactive protein (CRP) as model biomarker we demonstrate on-chip assay performance similar to conventional assays, with a LOD of 10 pg/ml and average CV of 9.7 % (48 microfluidic devices).

  • 82. Henareh, Loghman
    et al.
    Jedefors, Camilla
    Jogestrand, Tomas
    Brodin, Lars Åke
    KTH, School of Technology and Health (STH), Medical Engineering.
    Agewall, Stefan
    Intima-Media Thickness of Common Carotid and Brachial Arteries and Prothrombin Fragment 1+2 Are Associated with Left Ventricular Diastolic Dysfunction in Patients with Myocardial Infarction2010In: Echocardiography, ISSN 0742-2822, E-ISSN 1540-8175, Vol. 27, no 6, p. 651-658Article in journal (Refereed)
    Abstract [en]

    Aims: To investigate the association between intima-media thickness of brachial and common carotid arteries and factors of the coagulation- and fibrinolysis-system with left ventricular diastolic dysfunction in patients with a previous myocardial infarction. Patients and methods: One hundred and twenty three patients, men (76%) and women (24%) aged between 32and 81 years with a history of previous acute myocardial infarction were included. B-mode ultrasound of common carotid and brachial arteries and echocardiography with tissue Doppler imaging (TDI) were evaluated. Factors of the coagulation- and fibrinolysis-system were also measured. Results: In patients with previous myocardial infarction, late diastolic filling time was significantly and positively associated with log Prothrombin fragment 1 + 2 (P < 0.001) and with calculated intima-media area (cIMa) of the both common carotid and brachial arteries (P < 0.05). Mitral early-to-late flow velocity ratio (E/A) was significantly and negatively associated with log Prothrombin fragment 1 + 2 (P < 0.001), total cholesterol and cIMa of the both common carotid and brachial arteries (P < 0.05). Moreover both late diastolic filling time and mitral E/A correlated significantly with age and systolic blood pressure. In stepwise multiple regression analysis, log Prothrombin fragment 1 + 2 remained the only variable with independent significant correlation to late diastolic filling time and mitral E/A. Conclusions: In a population sample of patients with myocardial infarction, late diastolic filling time and mitral E/A were associated with cIMa of common carotid and brachial arteries, systolic blood pressure, and prothrombin fragment 1 + 2, suggesting a relationship between diastolic dysfunction, thrombin generation and atherosclerosis. (Echocardiography 2010;27:651-658).

  • 83. Herbst, Christian
    et al.
    Ternström, Sten
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    A comparison of different methods to measure the EGG contact quotient2006In: Logopedics, Phoniatrics, Vocology, ISSN 1401-5439, E-ISSN 1651-2022, Vol. 31, no 3, p. 126-138Article in journal (Refereed)
    Abstract [en]

    The results from six published electroglottographic (EGG-based) methods for calculating the EGG contact quotient (CQEGG) were compared to closed quotients derived from simultaneous videokymographic imaging (CQKYM). Two trained male singers phonated in falsetto and in chest register, with two degrees of adduction in both registers. The maximum difference between methods in the CQEGG was 0.3 (out of 1.0). The CQEGG was generally lower than the CQKYM. Within subjects, the CQEGG co-varied with the CQkym, but with changing offsets depending on method. The CQEGG cannot be calculated for falsetto phonation with little adduction, since there is no complete glottal closure. Basic criterion-level methods with thresholds of 0.2 or 0.25 gave the best match to the CQKYM data. The results suggest that contacting and de-contacting in the EGG might not refer to the same physical events as do the beginning and cessation of airflow.

  • 84.
    Holzapfel, Gerhard A.
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Biomechanics.
    Ogden, Ray W.
    Constitutive modelling of arteries2010In: Proceedings of the Royal Society. Mathematical, Physical and Engineering Sciences, ISSN 1364-5021, E-ISSN 1471-2946, Vol. 466, no 2118, p. 1551-1596Article, review/survey (Refereed)
    Abstract [en]

    This review article is concerned with the mathematical modelling of the mechanical properties of the soft biological tissues that constitute the walls of arteries. Many important aspects of the mechanical behaviour of arterial tissue can be treated on the basis of elasticity theory, and the focus of the article is therefore on the constitutive modelling of the anisotropic and highly nonlinear elastic properties of the artery wall. The discussion focuses primarily on developments over the last decade based on the theory of deformation invariants, in particular invariants that in part capture structural aspects of the tissue, specifically the orientation of collagen fibres, the dispersion in the orientation, and the associated anisotropy of the material properties. The main features of the relevant theory are summarized briefly and particular forms of the elastic strain-energy function are discussed and then applied to an artery considered as a thickwalled circular cylindrical tube in order to illustrate its extension-inflation behaviour. The wide range of applications of the constitutive modelling framework to artery walls in both health and disease and to the other fibrous soft tissues is discussed in detail. Since the main modelling effort in the literature has been on the passive response of arteries, this is also the concern of the major part of this article. A section is nevertheless devoted to reviewing the limited literature within the continuum mechanics framework on the active response of artery walls, i.e. the mechanical behaviour associated with the activation of smooth muscle, a very important but also very challenging topic that requires substantial further development. A final section provides a brief summary of the current state of arterial wall mechanical modelling and points to key areas that need further modelling effort in order to improve understanding of the biomechanics and mechanobiology of arteries and other soft tissues, from the molecular, to the cellular, tissue and organ levels.

  • 85.
    Hoseini, Mohammed
    et al.
    SP Swedish National Testing and Research Institute, Transport and Vehicle Technology, Building Technology and Mechanics, Borås.
    Jedenmalm, Anneli
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Mechanical Metallurgy.
    Boldizar, Antal
    Department of Materials and Manufacturing Technology, Chalmers University of Technology, Göteborg.
    Tribological investigation of coatings for artificial joints2008In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 264, no 11-12, p. 958-966Article in journal (Refereed)
    Abstract [en]

    A modified pin-on-disc machine was used for the tribological investigation of ultrahigh molecular weight polyethylene (UHMWPE) sliding on stainless steel or stainless steel coated with diamond-like carbon, titanium nitride or Micronite. Micronite is a new type of coating applied by a physical vapour deposition technique combined with a very low friction coating material giving improved tribological properties. The tribological parameters used were chosen to mimic the conditions prevailing in the human body. The wear debris and the counter-surfaces were analysed. The surface analysis showed that the coating changed the roughness of the counter-surfaces. The diamond-like carbon and Micronite coatings had a much higher surface roughness than the titanium nitride coating. The results indicated that the enhanced tribological behaviour of the Micronite/UHMWPE sliding pair might be used as a material combination in artificial joints. Further studies are however required in order to support this.

  • 86.
    Hu, Nan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Yuan, Feng
    Joint International Research Laboratory of Green Buildings and Built Environments (Ministry of Education), Chongqing University, Chongqing, China..
    Gram, Annika
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Yao, Runming
    Joint International Research Laboratory of Green Buildings and Built Environments (Ministry of Education), Chongqing University, Chongqing, China.; National Centre for International Research of Low-Carbon and Green Buildings (Ministry of Science and Technology), Chongqing University, Chongqing, China.; School of the Built Environment, University of Reading, Reading, UK..
    Sadrizadeh, Sasan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design. School of Business, Society and Engineering, Mälardalen University, Västerås, Sweden..
    Review of experimental measurements on particle size distribution and airflow behaviors during human respiration2024In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 247, article id 110994Article, review/survey (Refereed)
    Abstract [en]

    In recent years, pandemic outbreaks have raised concerns about the spread of respiratory infections and their impact on public health. Since the pathogen emission during human respiration is recognized as the primary source, characterizing the physical properties of exhaled particles and airflow has become a crucial focus of attention. This article critically reviews experimental studies in exhaled particles and airflow, examines the uncertainty introduced by different measurement methods, analyzes how it is reflected in measurement outcomes, and provides an in-depth understanding of particle size distribution and airflow behaviors of human respiration. The measurement techniques assessment highlights the variability among particle sizing techniques in detection size range, collection efficiency, hydration status of captured particles, and experimental protocols. A combination of sampling-based instruments and laser imaging systems is recommended for particle sizing to cover a wider detection range, with refined setups in thermal conditions, sampling distance, volume, and duration. Meanwhile, it identifies the complementary nature of qualitative and quantitative measurements of airflow characterization techniques. Image recording systems plus data reconstruction programs are suggested to capture dynamic airflow features while accuracy validation by other techniques is required at the same time. Subsequent analysis of the measurement data showed that the various experimental measurements provided substantial information, but they also revealed disagreements and challenges in quantification. The dominance of submicron aerosols in exhaled particles and jet-like transport in exhaled airflow is obvious. More efforts should be made to measure particles larger than 20 μm, capture airflow dynamics in a high temporal and spatial resolution, and quantify the impact of face coverings to improve the understanding of human respiratory emissions.

  • 87. Hurtig, Johan
    et al.
    Chiu, Daniel T.
    Önfelt, Björn
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Intercellular nanotubes: insights from imaging studies and beyond2010In: WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY, ISSN 1939-5116, Vol. 2, no 3, p. 260-276Article, review/survey (Refereed)
    Abstract [en]

    Cell-cell communication is critical to the development, maintenance, and function of multicellular organisms. Classical mechanisms for intercellular communication include secretion of molecules into the extracellular space and transport of small molecules through gap junctions. Recent reports suggest that cells also can communicate over long distances via a network of transient intercellular nanotubes. Such nanotubes have been shown to mediate intercellular transfer of organelles as well as membrane components and cytoplasmic molecules. Moreover, intercellular nanotubes have been observed in vivo and have been shown to enhance the transmission of pathogens such as human immunodeficiency virus (HIV)-1 and prions in vitro. These studies indicate that intercellular nanotubes may play a role both in normal physiology and in disease. (C) 2010 John Wiley & Sons, Inc. WIREs Nanomed Nanobiotechnol 2010 2 260-276

  • 88.
    Iseri, Emre
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Biggel, Michael
    Goossens, Herman
    Moons, Pieter
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Digital dipstick: miniaturized bacteria detection and digital quantification for the point-of-care2020In: Lab on a Chip, ISSN 1473-0197, Vol. 20, no 23, p. 4349-4356Article in journal (Refereed)
    Abstract [en]

    Established digital bioassay formats, digital PCR and digital ELISA, show extreme limits of detection, absolute quantification and high multiplexing capabilities. However, they often require complex instrumentation, and extensive off-chip sample preparation. In this study, we present a dipstick-format digital biosensor (digital dipstick) that detects bacteria directly from the sample liquid with a minimal number of steps: dip, culture, and count. We demonstrate the quantitative detection of Escherichia coli (E. coli) in urine in the clinically relevant range of 102 –105 CFU ml−1 for urinary tract infections. Our format shows 89% sensitivity to detect E. coli in clinical urine samples (n = 28) when it is compared to plate culturing (gold standard). The significance and uniqueness of this diagnostic test format is that it allows a non-trained operator to detect urinary tract infections in the clinically relevant range in the home setting.

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  • 89.
    Jacobsson, Martin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Navid, Zandpour
    Thorir, Sigmundsson
    Björne, Håkan
    Hällsjö Sander, Caroline
    Deep Learning-Based Early Prediction of Intraoperative Hypotension2021Conference paper (Refereed)
    Abstract [en]

    This work focuses on predicting near-term onset of hypotension prior to onset using convolutional neural networks. Based solely on the arterial blood pressure curve, our initial attempt can predict an onset with 60% sensitivity and 80% specificity 5-15 minutes before onset.

    Clinical relevance Hypotension is common during large surgery. By identifying and treating hypotensive episodes early, preferably even before onset, hypotension and its associate post- surgery complications are reduced. Even a prediction with 80% sensitivity/specificity is valuable for the anesthesiologist. 

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  • 90.
    Janerot Sjöberg, Birgitta
    et al.
    CLINTEC, Department of Medical Imaging and Technology, Karolinska Institute.
    Gonon, Adrian
    tutet (KI), Dept of Medicine.
    Grishenkov, Dmitry
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging. Karolinska Institutet (KI), CLINTEC – Division of Medical Imaging and Technology.
    In Search of the Optimal Ultrasound Heart Perfusion Imaging Platform2013Conference paper (Refereed)
  • 91.
    Jedenmalm, Anneli
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Computed Tomography of Acetabular Cup Wear and Effect of Surface Roughness on Wear and Oxidation of UHMWPE Hip Prostheses2007Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Aseptic loosening is the most common complication in total hip replacement (5- 10% at 10 years follow up). The magnitude of the problem is illustrated by the fact that about one million hip prostheses are implanted worldwide each year. Many parameters affect the longevity of the implant where aseptic loosening caused by wear debris and raised intraarticular pressure are the most common reasons for revisions. To monitor wear in vivo and also to predict the longevity of new materials for hip prostheses are therefore important issues.

    The main aims of this thesis are to validate a new non-invasive method for assessment of in vivo wear of acetabular cups in 3 dimensions using computed tomography (CT), and to investigate the influence of counterface surface roughness and γ-irradiation sterilisation in wear testing of ultra high molecular weight polyethylene (UHMWPE) for hip prostheses. A new low friction coating, Micronite was also investigated using a multidirectional pin-on-disk machine.

    The 3D-CT method was found to be easy to use and showed an accuracy and repeatability at a clinical relevant level for assessment of acetabular cup wear. The method should lend itself well to semi-automation. The Micronite coating showed potential for use in artificial joints due to its low friction and intact surface after wear testing compared to a stainless steel disk that showed wear tracks. However, the surface roughness of the stainless steel disks was increased by the coating. Therefore further investigations are needed. In the hip simulator study, it was found that a rougher counter surface increased the wear 2-fold. It was also found that sterilisation by γ-irradiation (in nitrogen) increased both fluid absorption and wear of the UHMWPE cups compared to the non-sterilised cups. A study with infrared spectroscopy and derivatisation techniques using NO, HCl, and SO2 showed that the increased wear and absorption were due to oxidation induced by γ-irradiation. The oxidation was found to be inhomogeneous with higher oxidation near the surfaces. The contribution of the roughened heads to the increased oxidation was only minor. Crystallinity changes upon wear testing of the sterilised cups were detected with Raman spectroscopy and differential scanning calorimetry. However, the changes were small and the influence on wear properties is therefore questionable.

  • 92.
    Jedenmalm, Anneli
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Affatato, S.
    Laboratorio di Tecnologia Medica, Istituti Ortopedici Rizzoli, Bologna.
    Taddei, P.
    Centro di Studio Sulla Spettroscopia Raman, Dipartimento di Biochimica G. Moruzzi, Università di Bologna, Bologna.
    Leardini, W.
    Laboratorio di Tecnologia Medica, Istituti Ortopedici Rizzoli, Bologna.
    Gedde, Ulf
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Fagnano, C.
    Centro di Studio Sulla Spettroscopia Raman, Dipartimento di Biochimica G. Moruzzi, Università di Bologna, Bologna.
    Viceconti, M.
    Laboratorio di Tecnologia Medica, Istituti Ortopedici Rizzoli, Bologna.
    Effect of head surface roughness and sterilization on wear of UHMWPE acetabular cups2009In: Journal of Biomedical Materials Research, ISSN 0021-9304, E-ISSN 1097-4636, Vol. 90, no 4, p. 1032-1042Article in journal (Refereed)
    Abstract [en]

    The impact of femoral head surface roughness on wear of gamma-irradiation sterilized (3 MRad in nitrogen, crosslinked) and nonsterilized (not crosshnked) UHMWPE acetabular cups has been evaluated. Gravimetric wear testing was performed in a hip joint simulator for 2 x 10(6) cycles. CoCrMo heads were used with different surface roughness (R-a = 15 nm and R-a = 400 rim). The surface roughness after wear test was unchanged for the roughened heads, whereas the initially smooth heads showed a few scratches. The roughened heads increased the wear of the acetabular cups 2-fold. The gamma-irradiated cups tested against rough heads underwent the highest wear. The absorption of water was highest for the gamma-irradiated cups (0.0204% compared to 0.0031% after 85 days). Raman spectroscopy showed small but significant crystallinity changes in the wear zone, where the gamma-irradiated cups with the most extensive abrasion increased in crystallinity, whereas the nonsterilized cups underwent a crystallinity decrease.

  • 93.
    Jedenmalm, Anneli
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Leardini, Walther
    Laboratorio di Tecnologia Medica, Istititi Ortppedci Rizzoli, Bologna.
    Zavalloni, Mara
    Laboratorio di Tecnologia Medica, Istititi Ortppedci Rizzoli, Bologna.
    Affatato, Saverio
    Laboratorio di Tecnologia Medica, Istititi Ortppedci Rizzoli, Bologna.
    Effect of head surface roughness and sterilization method on wear of UHMWPE acetabular cups: preliminary hip joint simulator results2006In: Proceedings of 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Vol. 3, 2006Conference paper (Refereed)
    Abstract [en]

    More than one million hip joint replacements are performed each year in the world. However, the implants do not last forever due to material limitations, even though the operation is successful. The most common material combination used today is a CoCr head articulating against an UHMWPE (Ultra High Molecular Weight Polyethylene) acetabular cup. Several investigations have shown that the metal head is roughened inside the body and thus accelerating wear of the polymer cup. The sterilization method is also known to have effect on the wear properties. In vitro wear tests are however usually performed with as new implants. This investigation aimed at study the impact of head surface roughness on wear of both sterilized and non-sterilized acetabular cups. A total of nine acetabular cup and head pairs were wear tested in a hip joint simulator for 2Million cycles (Mc) with bovine calf serum as lubricant. Wear was determined by weighing of all cups. The heads were of CoCrMo and the average initial head surface roughness was 15nm (R-a), measured with a white light interference profilometer. The roughening was produced with a SiC paper producing circular multidirectional wear tracks to a surface roughness of about 400nm (R-a). The cups were of UHMWPE and the sterilized cups were 3Mrad gamma-radiated in nitrogen. The surface roughness after wear test was unchanged for the roughened heads, while the initially smooth heads were slightly roughened. Preliminary results show that the rough heads increase the wear of the cups 2-fold. The gamma-irradiation affected both wear- and soak rate.

  • 94.
    Jedenmalm, Anneli
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Murgia, G.
    Corrosion- and Metals Research Institute, Stockholm.
    Jacobson, K.
    Corrosion- and Metals Research Institute, Stockholm.
    Gedde, Ulf
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Effect of γ-irradiation sterilization in nitrogen on oxidation of hip-simulated UHMWPE cupsManuscript (preprint) (Other academic)
    Abstract [en]

    A hip simulator study with roughened heads revealed unexpected high wear rates for the γ-irradiated UHMWPE cups (sterilization performed in nitrogen) and also higher fluid absorbtion than that of the non-sterilized cups. Infrared spectroscopy and high-resolution scanning of samples stained with HCl and SO2 showed that the outer parts of cross-sections of the sterilized cups were oxidized after the wear testing. The non-sterilized cups showed essentially no polymer oxidation with only minor surface oxidation due to roughened head. The higher wear rate and the more extensive fluid absorption of the sterilized cups is thus attributed to oxidation of the polymer; the latter presumably being facilitated by the presence of long-living radicals generated during γ-irradiation sterilization.

  • 95.
    Jedenmalm, Anneli
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Noz, Marilyn E.
    Department of Radiology, New York University School of Medicine, New York.
    Olivecrona, Henrik
    Department of Hand Surgery, Södersjukhuset, Stockholm.
    Olivecrona, Lofta
    Department of Radiology, Karolinska University Hospital Solna, Stockholm.
    Stark, Andre
    Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm.
    A new approach for assessment of wear in metal-backed acetabular cups using computed tomography: a phantom study with retrievals2008In: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 79, no 2, p. 218-224Article in journal (Refereed)
    Abstract [en]

    Background and purpose Polyethylene wear is an important cause of aseptic loosening in hip arthroplasty. Detection of significant wear usually happens late on, since available diagnostic techniques are either not sensitive enough or too complicated and expensive for routine use. This study evaluates a new approach for measurement of linear wear of metal-backed acetabular cups using CT as the intended clinically feasible method.

    Material and methods 8 retrieved uncemented metal-backed acetabular cups were scanned twice ex vivo using CT. The linear penetration depth of the femoral head into the cup was measured in the CT volumes using dedicated software. Landmark points were placed on the CT images of cup and head, and also on a reference plane in order to calculate the wear vector magnitude and angle to one of the axes. A coordinate-measuring machine was used to test the accuracy of the proposed CT method. For this purpose, the head diameters were also measured by both methods.

    Results Accuracy of the CT method for linear wear measurements was 0.6 nm and wear vector angle was 27 degrees. No systematic difference was found between CT scans.

    Interpretation This study on explanted acetabular cups shows that CT is capable of reliable measurement of linear wear in acetabular cups at a clinically relevant level of accuracy. It was also possible to use the method for assessment of direction of wear.

  • 96.
    Jess, David Unnersjö
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics.
    High-resolution Imaging of Cleared and Expanded Kidney Tissue Samples2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The kidney is one of the most important and complex organs in the humanbody with the task of filtering hundreds of litres of blood daily. It is responsiblefor the salt and acid/base balance in the body, as well as secretinghormones important for red blood cell production and blood pressure regulation. Kidney disease is one of the fastest growing causes of death in the modern world, and this motivates extensive research for better understandingthe function of the kidney in both health and disease. Kidney failure or end stage renal disease (ESRD) is irreversible and requires treatment with dialysisor transplantation. Some of the most important cellular structures for blood filtration in the kidney are of very small dimensions (below 200 nanometers), and thus electron microscopy has previously been the only method with high enough resolution to study the morphology and topology of these minute structures. In three studies included in this thesis, we show that the finest elements of the kidney can now be resolved using different light microscopy techniques. In study 1, we show that by combining optical clearing with STED microscopy, protein localizations in the slit diaphragm of the kidney can be resolved, with widths around 75 nanometers. In study 3, a novel sample preparation method, expansion microscopy, is utilized to isotropically expand kidney tissue samples in space. Expansion improves the effective resolution by a factor of 5, making it possible to resolve podocyte foot processes and the slit diaphragmusing diffraction-limited confocal microscopy. We also show that by combining expansion microscopy and STED microscopy, the effective resolution can be improved even further (<20 nm). In our most recent work, study 5, we apply a simplified, moderate tissue swelling protocol which together with optimization of the confocal imaging provides sufficient resolution to resolve foot processes and parts of the filtration barrier. This new protocol is fast and technically simple, making it ideal for routine use, such as for future clinical pathology. In collaboration with kidney researchers, we have applied both STED microscopy and expansion microscopy to various disease models, showing that these tools can be used to both visualize and quantify pathologies occurring in different parts of the glomerular filtration barrier (GFB). In study 2, STED microscopy in combination with optical clearing is used to study the localization of Coro2b in secondary foot processes in both mouse and human tissue. In two ongoing studies with preliminary results presented in the thesis, we use STED microscopy and optical clearing to study the pathogenesis of focal segmental glomerulosclerosis (FSGS) by the use of genetic mouse models. Based on STED images, we extract different morphological parameters from foot processes and the glomerular filtration barrier (GFB) at different stages of the disease. In study 4, we apply a tissue expansion protocol to answer questions about the phenotype seen in podocytes where the mediator complex subunit 22 (Med22) is inactivated. By inactivating Med22 in a transgenic mouse line with cytosolic expression of tdTomato in podocytes, we saw strong indications that the vesicle-like structures seen in EM micrographs were indeed intracellular vesicles and not dilated sub-podocyte space. In summary, the work presented in this thesis has contributed to the development of a new toolbox for imaging renal ultra-structure using light microscopy, a field previously reserved for electron microscopy.

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  • 97.
    Jönsson, Håkan
    et al.
    KTH, School of Biotechnology (BIO), Nano Biotechnology.
    Samuels, Michael L.
    Brouzes, Eric R.
    Medkova, Martina
    Uhlén, Mathias
    KTH, School of Biotechnology (BIO), Proteomics.
    Link, Darren R.
    Andersson-Svahn, Helene
    KTH, School of Biotechnology (BIO), Nano Biotechnology.
    Detection and Analysis of Low-Abundance Cell-Surface Biomarkers Using Enzymatic Amplification in Microfluidic Droplets2009In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 48, no 14, p. 2518-2521Article in journal (Refereed)
    Abstract [en]

    Finding the few: Cell-surface proteins are useful disease biomarkers, but current high-throughput methods are limited to detecting cells expressing more than several hundred proteins. Enzymatic amplification in microfluidic droplets (see picture) is a high-throughput method for detection and analysis of cell-surface biomarkers expressed at very low levels on individual human cells. Droplet optical labels allow concurrent analysis of several samples.

  • 98.
    Jönsson, Håkan
    et al.
    KTH, School of Biotechnology (BIO), Nano Biotechnology.
    Svahn Andersson, Helene
    KTH, School of Biotechnology (BIO), Nano Biotechnology.
    Tröpfchen-Mikrofluidik für die Einzelzellanalyse2012In: Angewandte Chemie, ISSN 0044-8249, E-ISSN 1521-3757, Angewandte Chemie, Vol. 124, no 49, p. 12342-12359Article in journal (Refereed)
    Abstract [de]

    Die tröpfchenbasierte Mikrofluidik dient der Isolierung und Manipulation von einzelnen Zellen und Reagentien innerhalb von monodispersen, pikolitergroßen Flüssigkapseln bei einem Umsatz von tausenden Tröpfchen pro Sekunde. Diese Qualitäten machen die Tröpfchen‐Mikrofluidik geeignet für viele Anforderungen der Einzelzellanalyse. Durch die Monodispersität lässt sich die Konzentration in den Tröpfchen quantitativ einstellen. Die Tröpfchen bieten der Zelle und ihrer unmittelbaren Umgebung ein isoliertes Kompartiment, und bei einem Durchsatz von tausenden Tröpfchen pro Sekunde ist es möglich, zehntausende bis millionen verkapselte Zellen zu prozessieren. Heterogene Zellpopulationen lassen sich somit exakt beschreiben oder seltene Zellarten identifizieren. Das kleine Volumen der Tröpfchen macht auch sehr große Screenings ökonomisch machbar. Dieser Aufsatz gibt einen Überblick über den aktuellen Stand der Einzelzellanalyse durch die Tröpfchen‐Mikrofluidik und nennt Beispiele, bei denen sie biologische Vorgänge besser verstehen hilft.

  • 99.
    Kasai, Nahoko
    et al.
    Nippon Telegraph and Telephone Corporation.
    Shimada, Akiyoshi
    Nippon Telegraph and Telephone Corporation.
    Nyberg, Tobias
    Nippon Telegraph and Telephone Corporation.
    Torimitsu, Keiichi
    Nippon Telegraph and Telephone Corporation.
    Fabrication of an electrochemical sensor array for 2D H2O2 imaging2006In: Electrochemistry (Tokyo. 1999), ISSN 1344-3542, Vol. 74, no 8, p. 628-631Article in journal (Refereed)
    Abstract [en]

    To achieve accurate real-time 2D H2O2 distribution imaging, we fabricated an H2O2 sensor array by dispensing small quantities of enzyme solution very accurately onto electrodes in an electrode array. We confirmed the accuracy of the dispensing technique. We then investigated the responses of each sensor to H2O2 injection using a 64-channel multipotentiostat and found they varied by 20%. Real-time 2D H2O2 imaging was therefore successfully realized by using our flow cell system. This sensor array will be useful for the non-invasive, real-time monitoring of the H2O2 distribution in biological samples.

  • 100.
    Kifle, Mengistu
    et al.
    KTH, School of Information and Communication Technology (ICT), Computer and Systems Sciences, DSV.
    Mbarika, Victor W. A.
    Datta, Pratim
    Interplay of cost and adoption of tele-medicine in Sub-Saharan Africa: The case of tele-cardiology in Ethiopia2006In: Information Systems Frontiers, ISSN 1387-3326, E-ISSN 1572-9419, Vol. 8, no 3, p. 211-223Article in journal (Refereed)
    Abstract [en]

    ...the barriers to diffusion of Tele-Medicine are not entirely technical. Cost has to simultaneously satisfy a number of stakeholders... (Anderson, Aydin and Jay, et al., 1994).

    Rising costs of the provision of healthcare have been a major issue for debate in both developing and developed countries. This is especially true of very capitalistic societies such as the United States where privatization of the healthcare sector has left many with little or no affordable healthcare. The situation is even worse in developing economies. Developing countries deal with various problems in the provision of health services and healthcare Tan et al. (E-medicine diffusion: E-medicine in Developed and Developing countries. Chapter 8 in E-health paradigm shift: Perspectives, domains and challenges. In Tan J. (Ed.), Imprint of Wiley, New York, Jossey-Bass, 2005). Some of these problems include acute shortages of healthcare professionals and medical facilities Mbarika et al. (Journal of the Association for Information Systems (JAIS) 2005;6(5):130-170). Such shortages have resulted in growing numbers of middle to upper-class citizens of developing countries traveling abroad to seek necessary health services. Using a multi-method case study research, this paper examines the role of Tele-Medicine in the healthcare system and analyzes the costs and benefits of introducing Tele-Cardiology services in Ethiopia (a Sub-Saharan African country). This is a cost comparison study for the treatment of cardiac patients traveling abroad versus patients treated via Tele-Cardiology. Our findings show that Tele-Cardiology is clinically more feasible and more cost effective compared to patients traveling abroad for treatment.

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