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Maguire Jr., Gerald Q.ORCID iD iconorcid.org/0000-0002-6066-746X
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Publications (10 of 295) Show all publications
Olivecrona, H., Maguire, G. Q. ., Noz, M. E., Zeleznik, M. P., Kesteris, U. & Weidenhielm, L. (2016). A CT method for following patients with both prosthetic replacement and implanted tantalum beads: preliminary analysis with a pelvic model and in seven patients. Journal of Orthopaedic Surgery and Research, 11, Article ID 27.
Open this publication in new window or tab >>A CT method for following patients with both prosthetic replacement and implanted tantalum beads: preliminary analysis with a pelvic model and in seven patients
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2016 (English)In: Journal of Orthopaedic Surgery and Research, ISSN 1749-799X, E-ISSN 1749-799X, Vol. 11, 27Article in journal (Refereed) Published
Abstract [en]

Background: Radiostereometric analysis (RSA) is often used for evaluating implanted devices over time. Following patients who have had tantalum beads implanted as markers in conjunction with joint replacements is important for longitudinal evaluation of these patients and for those with similar implants. As doing traditional RSA imaging is exacting and limited to specialized centers, it is important to consider alternative techniques for this ongoing evaluation. This paper studies the use of computed tomography (CT) to evaluate over time tantalum beads which have been implanted as markers. Methods: The project uses both a hip model implanted with tantalum beads, acquired in several orientations, at two different CT energy levels, and a cohort of seven patients. The model was evaluated twice by the same observer with a 1-week interval. All CT volumes were analyzed using a semi-automated 3D volume fusion (spatial registration) tool which provides landmark-based fusion of two volumes, registering a target volume with a reference volume using a rigid body 3D algorithm. The mean registration errors as well as the accuracy and repeatability of the method were evaluated. Results: The mean registration error, maximum value of repeatability, and accuracy for the relative movement in the model were 0.16 mm, 0.02 degrees and 0.1 mm, and 0.36 degrees and 0.13 mm for 120 kVp and 0.21 mm, 0.04 degrees and 0.01 mm, and 0.39 degrees and 0.12 mm for 100 kVp. For the patients, the mean registration errors per patient ranged from 0.08 to 0.35 mm. These results are comparable to those in typical clinical RSA trials. This technique successfully evaluated two patients who would have been lost from the cohort if only RSA were used. Conclusions: The proposed technique can be used to evaluate patients with tantalum beads over time without the need for stereoradiographs. Further, the effective dose associated with CT is decreasing.

Place, publisher, year, edition, pages
BioMed Central, 2016
Keyword
Radiostereometry, Longitudinal studies, CT analysis, RSA
National Category
Medical Image Processing
Identifiers
urn:nbn:se:kth:diva-183622 (URN)10.1186/s13018-016-0360-7 (DOI)000370777100001 ()2-s2.0-84959129104 (Scopus ID)
Note

QC 20160319

Available from: 2016-03-19 Created: 2016-03-18 Last updated: 2017-11-30Bibliographically approved
Brodén, C., Olivecrona, H., Maguire Jr., G. Q., Noz, M. E., Zeleznik, M. P. & Sköldenberg, O. (2016). Accuracy and Precision of Three-Dimensional Low Dose CT Compared to Standard RSA in Acetabular Cups: An Experimental Study. BioMed Research International, Article ID 5909741.
Open this publication in new window or tab >>Accuracy and Precision of Three-Dimensional Low Dose CT Compared to Standard RSA in Acetabular Cups: An Experimental Study
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2016 (English)In: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, 5909741Article in journal (Refereed) Published
Abstract [en]

Background and Purpose. The gold standard for detection of implant wear and migration is currently radiostereometry (RSA). The purpose of this study is to compare a three-dimensional computed tomography technique (3D CT) to standard RSA as an alternative technique for measuring migration of acetabular cups in total hip arthroplasty.

Materials and Methods. With tantalum beads, we marked one cemented and one uncemented cup and mounted these on a similarly marked pelvic model. A comparison was made between 3D CT and standard RSA for measuring migration. Twelve repeated stereoradiographs and CT scans with double examinations in each position and gradual migration of the implants were made. Precision and accuracy of the 3D CT were calculated.

Results. The accuracy of the 3D CT ranged between 0.07 and 0.32 mm for translations and 0.21 and 0.82° for rotation. The precision ranged between 0.01 and 0.09 mm for translations and 0.06 and 0.29° for rotations, respectively. For standard RSA, the precision ranged between 0.04 and 0.09 mm for translations and 0.08 and 0.32° for rotations, respectively. There was no significant difference in precision between 3D CT and standard RSA. The effective radiation dose of the 3D CT method, comparable to RSA, was estimated to be 0.33 mSv.

Interpretation. Low dose 3D CT is a comparable method to standard RSA in an experimental setting.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2016
National Category
Orthopaedics Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:kth:diva-189725 (URN)10.1155/2016/5909741 (DOI)
Available from: 2016-07-11 Created: 2016-07-11 Last updated: 2018-01-10Bibliographically approved
Kim, Y. S., Maguire Jr., G. Q. & Noz, M. E. (2016). Do Small-Mass Neutrinos Participate in Gauge Transformations?. Advances in High Energy Physics, 1-7, Article ID 1847620.
Open this publication in new window or tab >>Do Small-Mass Neutrinos Participate in Gauge Transformations?
2016 (English)In: Advances in High Energy Physics, ISSN 1687-7357, E-ISSN 1687-7365, 1-7 p., 1847620Article in journal (Refereed) Published
Abstract [en]

Neutrino oscillation experiments presently suggest that neutrinos have a small but finite mass. If neutrinos have mass, there should be a Lorentz frame in which they can be brought to rest. This paper discusses how Wigner’s little groups can be used to distinguish between massive and massless particles. We derive a representation of the SL(2,c) group which separates out the two sets of spinors: one set is gauge dependent and the other set is gauge invariant and represents polarized neutrinos. We show that a similar calculation can be done for the Dirac equation. In the large-momentum/zero-mass limit, the Dirac spinors can be separated into large and small components. The large components are gauge invariant, while the small components are not. These small components represent spin-1/2 non-zero-mass particles. If we renormalize the large components, these gauge invariant spinors represent the polarization of neutrinos. Massive neutrinos cannot be invariant under gauge transformations.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2016
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-189756 (URN)10.1155/2016/1847620 (DOI)2-s2.0-84979656442 (Scopus ID)
Note

QC 20160713

Available from: 2016-07-13 Created: 2016-07-13 Last updated: 2017-11-28Bibliographically approved
Yalew, S. D., Maguire Jr., G. Q. & Correia, M. (2016). Light-SPD: a platform to prototype secure mobile applications. In: Proceedings of the 1st ACM Workshop on Privacy-Aware Mobile Computing (PAMCO '16): . Paper presented at 1st ACM Workshop on Privacy-Aware Mobile Computing (PAMCO '16) (pp. 11-20). New York, NY, USA: Association for Computing Machinery (ACM).
Open this publication in new window or tab >>Light-SPD: a platform to prototype secure mobile applications
2016 (English)In: Proceedings of the 1st ACM Workshop on Privacy-Aware Mobile Computing (PAMCO '16), New York, NY, USA: Association for Computing Machinery (ACM), 2016, 11-20 p.Conference paper, Published paper (Refereed)
Abstract [en]

Securely storing sensitive personal data is critical for protecting privacy. Currently, many persons use smartphones to store their private data. However, smartphones suffer from many security issues. To overcome this situation, the PCAS project is designing a secure personal storage device called the Secure Portable Device (SPD), to be attached to a smartphone for securely storing sensitive personal data. However, this device is unavailable, closed, and expensive to deploy for prototyping applications. We propose a platform that emulates the SPD and the smartphone using a board with an ARM processor with the TrustZone security extension. This platform is open, inexpensive, and secure. A payment application is used as an example to show the platform's capabilities. As a proof-of-concept, we implemented this platform and provide a performance evaluation using a i.MX53 board.

Place, publisher, year, edition, pages
New York, NY, USA: Association for Computing Machinery (ACM), 2016
Keyword
Mobile Computing, Privacy, Hardware Security, Trusted Computing, ARM TrustZone
National Category
Communication Systems Computer Systems
Identifiers
urn:nbn:se:kth:diva-189742 (URN)10.1145/2940343.2940349 (DOI)978-1-4503-4346-6 (ISBN)
Conference
1st ACM Workshop on Privacy-Aware Mobile Computing (PAMCO '16)
Note

QC 20160719

Available from: 2016-07-12 Created: 2016-07-12 Last updated: 2016-07-19Bibliographically approved
Svedmark, P., Berg, S., Noz, M. E., Maguire Jr., G. Q., Zeleznik, M. P., Weidenhielm, L., . . . Olivecrona, H. (2015). A New CT Method for Assessing 3D Movements in Lumbar Facet Joints and Vertebrae in Patients before and after TDR. BioMed Research International, 2015, 1-9, Article ID 260703.
Open this publication in new window or tab >>A New CT Method for Assessing 3D Movements in Lumbar Facet Joints and Vertebrae in Patients before and after TDR
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2015 (English)In: BioMed Research International, ISSN 2314-6133, Vol. 2015, 1-9 p., 260703Article in journal (Refereed) Published
Abstract [en]

This study describes a 3D-CT method for analyzing facet joint motion and vertebral rotation in the lumbar spine after TDR. Ten patients were examined before and then three years after surgery, each time with two CT scans: provoked flexion and provoked extension. After 3D registration, the facet joint 3D translation and segmental vertebral 3D rotation were analyzed at the operated level (L5-S1) and adjacent level (L4-L5). Pain was evaluated using VAS. The median (±SD) 3D movement in the operated level for the left facet joint was 3.2 mm (±1.9 mm) before and 3.5 mm (±1.7 mm) after surgery and for the right facet joint was 3.0 mm (±1.0 mm) before and 3.6 mm (±1.4 mm) after surgery. The median vertebral rotation in the sagittal plane at the operated level was 5.4° (±2.3°) before surgery and 6.8° (±1.7°) after surgery and in the adjacent level was 7.7° (±4.0°) before and 9.2° (±2.7°) after surgery. The median VAS was reduced from 6 (range 5–8) to 3 (range 2–8) in extension and from 4 (range 2–6) to 2 (range 1–3) in flexion.

National Category
Orthopaedics Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:kth:diva-176268 (URN)10.1155/2015/260703 (DOI)2-s2.0-84947475183 (Scopus ID)
Note

QC 20151102

Available from: 2015-11-02 Created: 2015-11-02 Last updated: 2018-01-10Bibliographically approved
Lee, S., Noz, M. E. & Maguire Jr., G. Q. (2015). Dynamic PET visualization of bone remodeling using NaF-18. Stockholm: KTH Royal Institute of Technology.
Open this publication in new window or tab >>Dynamic PET visualization of bone remodeling using NaF-18
2015 (English)Report (Other academic)
Abstract [en]

Positron emission tomography (PET) studies acquired in list mode offer the opportunity to provide a cine loop showing the dynamics of 18F- PET uptake, giving a visualization of regional bone remodeling. The focus of this report is a group of patients treated with Taylor spatial frames (TSF). The studies were acquired for a period of 45 minutes and saved in list mode. The list was decoded and subsequently segmented into time intervals of one minute each. For each time interval a sinogram was generated from which volumes of one minute each were reconstructed. Slices projected from these volumes could then be displayed as a dynamic loop superimposed on the corresponding computed tomography (CT) slice in order to visualize the 18F- uptake insitu. It was indicated that this technique has the potential of becoming an additional technique to that of using static volumes and SUV values only.

As the list mode data was decoded it also offered a method to evaluate the potential decrease in injected activity by eliminating every Nth event from the list before reconstructing the 45 minute volume. This was done and the indication was that the injected activity and hence the effective dose to the patient can be decreased. However, in this work, this was not proven clinically.

The open source STIR software was used to reconstruct volumes from sinograms to enable an unlimited access to reconstructing volumes without disturbing the daily routine at the clinic. The data was acquired on a clinical Siemens Medical Solutions Biograph 64 TruePoint TrueV, PET/CT scanner situated at the Nuclear Medicine Department at the Karolinska University Hospital in Solna. This scanner was not supported by the STIR software, hence the data collected by the Siemens PET/CT scanner was translated so that 3D reconstructions could be computed using the STIR tools. The reconstructions made in STIR resulted in volumes of sufficient visual quality, but not as good as those reconstructed by the scanner itself. Further optimization in STIR was left for future work.

According to the physicians who treat these patients, dynamic visualization was of sufficient interest to continue to develop and optimize this method. The cine loops that were presented to the physicians were made from JPEG slices produced from the one minute volumes and put together as GIF files. It was also possible to vary the reconstruction time (from uniformly one minute) as well as the presentation rate in the cine loop, but this was left for future work. Ultimately, the cine loop will be implemented in the locally developed software tool.

Abstract [sv]

Positronemissionstomografi (PET) studier som förvärvats i list mode erbjuder möjligheten att göra film slingor som visar dynamiken i 18F- PET upptag. Detta förväntas ge en dynamisk visualisering av var ben nybildas. Fokus i denna rapport är en grupp patienter som behandlats med Taylor spatial frames (TSF). Bilderna i studien förvärvades under en period av 45 minuter och sparades i list mode. List mode data avkodades och delades därefter upp i tidsintervaller på en minut vardera. För varje tidsintervall rekonstruerades ett sinogram för vilka bilder av volymen rekonstruerades. Skivor från dessa volymer kan sedan visas som en dynamisk slinga ovanpå motsvarande datortomografi (CT) skiva för att visualisera 18F- upptaget in situ. Denna teknik visade sig ha potential att bli en ytterligare teknik utöver de statiska volymer och SUV-värden som redan finns tillgängliga.

Eftersom listmode data avkodats erbjuds också en metod för att utvärdera en potentiell minskning av den injicerade aktivitet genom att eliminera varje N: te händelse från listan innan volymen på 45 minuter rekonstrueras. Detta utfördes och det visade sig att den injicerade aktiviteten och därmed den effektiva dosen till patienten potentiellt kan minskas men i detta arbete har detta inte bevisats kliniskt.

Mjukvaran STIR, som är tillgängligt för allmänheten, användes för att rekonstruera volymer från sinogram för att möjliggöra en obegränsad tillgång till att rekonstruera volymer utan att störa den dagliga rutinen på kliniken. Data förvärvades i en klinisk Siemens Medical Solutions Biograph 64 TruePoint TrueV, PET/CT-skanner som är placerad vid nuklearmedicinska avdelningen vid Karolinska Universitetssjukhuset i Solna. Skannern var inte kompatibel med STIR mjukvaran. Därför översattes det data som samlats in av Siemens PET/CT-skannern så att 3D-rekonstruktioner kan beräknas med hjälp av verktygen i STIR. De rekonstruktioner som gjorts i STIR gav upphov till volymer av tillräcklig visuell kvalitet för denna studie, men var inte lika bra som de som rekonstrueras genom själva skannern. Ytterligare optimering i STIR lämnades för framtida arbete.

Enligt de läkare som behandlar dessa patienter var en dynamisk visualisering av tillräckligt intresse att fortsätta utveckla och optimera den här metoden. Film slingor som presenterades för läkarna gjordes från JPEG bilder tagna från skivor av volymer på en minut vardera som producerats och sattes ihop som GIF-filer. Det var också möjligt att variera återuppbyggnadstiden (från jämnt en minut) samt presentationshastigheten i film slingan, men detta lämnades till framtida arbetet. I slutändan kommer film slingan implementeras i ett lokalt utvecklat verktyg.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. xvii,131 p.
Series
TRITA-ICT, 2015:24
Keyword
PET, Image Reconstruction, Dynamic Visualization, List Mode, STIR, PET, Bildrekonstruktion, Dynamisk visualisering, List mode, STIR
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:kth:diva-176272 (URN)
Note

QC 20151102

Available from: 2015-11-02 Created: 2015-11-02 Last updated: 2015-11-17Bibliographically approved
Skeppholm, M., Svedmark, P., Noz, M. E., Maguire Jr., G. Q., Olivecrona, H. & Olerud, C. (2015). Evaluation of mobility and stability in the Discover artificial disc: an in vivo motion study using high-accuracy 3D CT data. Journal of Eurosurgery : Spine, 23(3), 383-389.
Open this publication in new window or tab >>Evaluation of mobility and stability in the Discover artificial disc: an in vivo motion study using high-accuracy 3D CT data
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2015 (English)In: Journal of Eurosurgery : Spine, ISSN 1547-5654, E-ISSN 1547-5646, Vol. 23, no 3, 383-389 p.Article in journal (Refereed) Published
Abstract [en]

OBJECT Artificial disc replacement (ADR) devices are unlike implants used in cervical fusion in that they are continuously exposed to stress not only within the implant site but also at their site of attachment to the adjacent vertebra. An imaging technique with higher accuracy than plain radiography and with the possibility of 3D visualization would provide more detailed information about the motion quality and stability of the implant in relation to the vertebrae. Such high-accuracy studies have previously been conducted with radiostereometric analysis (RSA), which requires implantation of tantalum markers in the adjacent vertebrae. The aim of this study was to evaluate in vivo motion and stability of implanted artificial discs. A noninvasive analysis was performed with CT, with an accuracy higher than that of plain radiographs and almost as high as RSA in cervical spine. METHODS Twenty-eight patients with ADR were included from a larger cohort of a randomized controlled trial comparing treatment of cervical radiculopathy with ADR or anterior cervical decompression and fusion. Surgical levels included C4-7; 18 patients had 1-level surgery and 10 patients had 2-level surgery. Follow-up time ranged from 19 to 50 months, with an average of 40 months. Two CT volumes of the cervical spine, 1 in flexion and 1 in extension, were obtained in each patient and then spatially registered using a customized imaging tool, previously used and validated for the cervical spine. Motion between the components in the artificial disc, as well as motion between the components and adjacent vertebrae, were calculated in 3 planes. Intraclass correlation (ICC) between independent observers and repeatability of the method were also calculated. RESULTS Intrinsic motion, expressed as degrees in rotation and millimeters in translation, was detectable in a majority of the ADRs. In the sagittal plane, in which the flexion/extension was performed, sagittal rotation ranged between 0.2 and 15.8 and translation between 0.0 and 5.5 mm. Eight percent of the ADRs were classified as unstable, as motion between at least 1 of the components and the adjacent vertebra was detected. Five percent were classified as ankylotic, with no detectable motion, and another 8% showed very limited motion due to heterotopic ossification. Repeatability for the motion in the sagittal plane was calculated to be 1.300 for rotation and 1.29 mm for translation (95% confidence level), ICC 0.99 and 0.84, respectively. All 3 patients with unstable devices had undergone 1-level ADRs at C5-6. They all underwent revision surgery due to increased neck pain, and instability was established during the surgery. CONCLUSIONS The majority of the artificial discs in this study showed intrinsic mobility several years after implantation and were also shown to be properly attached. Implant instability was detected in 8% of patients and, as all of these patients underwent revision surgery due to increasing neck pain, this might be a more serious problem than heterotopic bone formation.

Place, publisher, year, edition, pages
AMER ASSOC NEUROLOGICAL SURGEONS, 2015
Keyword
artificial disc replacement, mobility, computed tomography, instability, revision surgery
National Category
Neurology Surgery
Identifiers
urn:nbn:se:kth:diva-173426 (URN)10.3171/2014.12.SPINE14813 (DOI)000360027300018 ()2-s2.0-84947447284 (Scopus ID)
Note

QC 20150915. QC 20160222

Available from: 2015-09-15 Created: 2015-09-11 Last updated: 2017-12-04Bibliographically approved
Bogdanov, K., Peón-Quirós, M., Maguire Jr., G. Q. & Kostic, D. (2015). The Nearest Replica Can Be Farther Than You Think. In: Proceedings of the ACM Symposium on Cloud Computing 2015: . Paper presented at ACM Symposium on Cloud Computing August 27 - 29, 2015,Hawaii (pp. 16-29). Association for Computing Machinery (ACM).
Open this publication in new window or tab >>The Nearest Replica Can Be Farther Than You Think
2015 (English)In: Proceedings of the ACM Symposium on Cloud Computing 2015, Association for Computing Machinery (ACM), 2015, 16-29 p.Conference paper, Published paper (Refereed)
Abstract [en]

Modern distributed systems are geo-distributed for reasons of increased performance, reliability, and survivability. At the heart of many such systems, e.g., the widely used Cassandra and MongoDB data stores, is an algorithm for choosing a closest set of replicas to service a client request. Suboptimal replica choices due to dynamically changing network conditions result in reduced performance as a result of increased response latency. We present GeoPerf, a tool that tries to automate the process of systematically testing the performance of replica selection algorithms for geodistributed storage systems. Our key idea is to combine symbolic execution and lightweight modeling to generate a set of inputs that can expose weaknesses in replica selection. As part of our evaluation, we analyzed network round trip times between geographically distributed Amazon EC2 regions, and showed a significant number of daily changes in nearestK replica orders. We tested Cassandra and MongoDB using our tool, and found bugs in each of these systems. Finally, we use our collected Amazon EC2 latency traces to quantify the time lost due to these bugs. For example due to the bug in Cassandra, the median wasted time for 10% of all requests is above 50 ms.

Place, publisher, year, edition, pages
Association for Computing Machinery (ACM), 2015
Keyword
Geo-Distributed Systems, Replica Selection Algorithms, Symbolic Execution
National Category
Communication Systems Computer Systems Computer Sciences
Identifiers
urn:nbn:se:kth:diva-171434 (URN)10.1145/2806777.2806939 (DOI)000380606400002 ()2-s2.0-84958960133 (Scopus ID)
External cooperation:
Conference
ACM Symposium on Cloud Computing August 27 - 29, 2015,Hawaii
Funder
EU, European Research Council, 259110
Note

To obtain the data used in this work please contact dmk@kth.se and kirillb@kth.se.

QC 20150812

Available from: 2015-08-03 Created: 2015-08-03 Last updated: 2018-01-11Bibliographically approved
Bogdanov, K., Peón-Quirós, M., Maguire Jr., G. Q. & Kostić, D. (2015). Toward Automated Testing of Geo-Distributed Replica Selection Algorithms. In: Proceedings of the 2015 ACM Conference on Special Interest Group on Data Communication: . Paper presented at 2015 ACM Conference on Special Interest Group on Data Communication (pp. 89-90). Association for Computing Machinery (ACM).
Open this publication in new window or tab >>Toward Automated Testing of Geo-Distributed Replica Selection Algorithms
2015 (English)In: Proceedings of the 2015 ACM Conference on Special Interest Group on Data Communication, Association for Computing Machinery (ACM), 2015, 89-90 p.Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

Many geo-distributed systems rely on a replica selection algorithms to communicate with the closest set of replicas.  Unfortunately, the bursty nature of the Internet traffic and ever changing network conditions present a problem in identifying the best choices of replicas. Suboptimal replica choices result in increased response latency and reduced system performance. In this work we present GeoPerf, a tool that tries to automate testing of geo-distributed replica selection algorithms. We used GeoPerf to test Cassandra and MongoDB, two popular data stores, and found bugs in each of these systems.

Place, publisher, year, edition, pages
Association for Computing Machinery (ACM), 2015
Series
SIGCOMM ’15
Keyword
replica selection algorithms, software testing and debugging, symbolic execution, wide area networks
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-173882 (URN)10.1145/2785956.2790013 (DOI)000370556200009 ()2-s2.0-84962237699 (Scopus ID)
Conference
2015 ACM Conference on Special Interest Group on Data Communication
Funder
EU, European Research Council, ERC project 259110.
Note

QC 20150923. QC 20160407

Available from: 2015-09-22 Created: 2015-09-22 Last updated: 2016-04-07Bibliographically approved
Lundblad, H., Maguire Jr., G. Q., Karlsson-Thur, C., Jonsson, C., Noz, M. E., Zeleznik, M. P., . . . Weidenhielm, L. (2015). Using PET/CT Bone Scan Dynamic Data to Evaluate Tibia Remodeling When a Taylor Spatial Frame Is Used: Short and Longer Term Differences. BioMed Research International, 2015, 1-11, Article ID 574705.
Open this publication in new window or tab >>Using PET/CT Bone Scan Dynamic Data to Evaluate Tibia Remodeling When a Taylor Spatial Frame Is Used: Short and Longer Term Differences
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2015 (English)In: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, Vol. 2015, 1-11 p., 574705Article in journal (Refereed) Published
Abstract [en]

Eighteen consecutive patients, treated with a Taylor Spatial Frame for complex tibia conditions, gave their informed consentto undergo Na18F− PET/CT bone scans. We present a Patlak-like analysis utilizing an approximated blood time-activity curveeliminating the need for blood aliquots. Additionally, standardized uptake values (SUV) derived from dynamic acquisitions werecompared to this Patlak-like approach. Spherical volumes of interest (VOIs) were drawn to include broken bone, other (normal)bone, and muscle. The SUV𝑚(𝑡) (𝑚 = max, mean) and a series of slopes were computed as (SUV𝑚(𝑡𝑖) − SUV𝑚(𝑡𝑗))/(𝑡𝑖 − 𝑡𝑗), forpairs of time values 𝑡𝑖 and 𝑡𝑗. A Patlak-like analysis was performed for the same time values by computing ((VOI𝑝(𝑡𝑖)/VOI𝑒(𝑡𝑖)) −(VOI𝑝(𝑡𝑗)/VOI𝑒(𝑡𝑗)))/(𝑡𝑖−𝑡𝑗), where p = broken bone, other bone, andmuscle and e = expected activity in aVOI. Paired comparisonsbetween Patlak-like and SUV𝑚 slopes showed good agreement by both linear regression and correlation coefficient analysis(𝑟 = 84%, 𝑟𝑠 = 78%-SUVmax, 𝑟 = 92%, and 𝑟𝑠 = 91%-SUVmean), suggesting static scans could substitute for dynamic studies.Patlak-like slope differences of 0.1 min−1 or greater between examinations and SUVmax differences of ∼5 usually indicated goodremodeling progress, while negative Patlak-like slope differences of −0.06 min−1 usually indicated poor remodeling progress in thiscohort.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2015
National Category
Orthopaedics Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:kth:diva-173247 (URN)10.1155/2015/574705 (DOI)000361696200001 ()
Note

QC 20150910

Available from: 2015-09-08 Created: 2015-09-08 Last updated: 2018-01-11Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6066-746X

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