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Sundström, Torbjörn
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Publications (10 of 15) Show all publications
Unéus, E., Wilhelmsson, C., Suhr, O., Anan, I., Wixner, J., Pilebro, B., . . . Sundström, T. (2019). Visualisation of amyloid deposition within the brain of long-term hereditary transthyretin amyloidosis survivors by 18F-flutemetamol positron emission tomography. Paper presented at 5th Congress of the European Academy of Neurology (EAN), June 29 – July 2, 2019, Oslo, Norway. European Journal of Neurology, 26(S1), 287-287, Article ID EPR3027.
Open this publication in new window or tab >>Visualisation of amyloid deposition within the brain of long-term hereditary transthyretin amyloidosis survivors by 18F-flutemetamol positron emission tomography
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2019 (English)In: European Journal of Neurology, ISSN 1351-5101, E-ISSN 1468-1331, Vol. 26, no S1, p. 287-287, article id EPR3027Article in journal, Meeting abstract (Other academic) Published
Abstract [en]

Background and aims: Hereditary transthyretin amyloid (ATTRv) amyloidosis caused by the transthyretin (TTR) Val30Met (p.V50M) mutation is characterised by peripheral neuropathy, and central nervous (CNS) complications has rarely been reported. However, liver transplantation has prolonged the patients’ survival, and CNS complications attributed to amyloid angiopathy caused by CNS synthesis of variant TTR have been reported. The aim of the study was to ascertain CNS amyloid deposition in long-term ATTRv survivors.

Methods: 20 ATTR Val30Met patients with symptoms from the CNS and a median disease duration of 16 years (9-25 years) together with five Alzheimer (AD) patients, who served as positive controls were included in the study. Amyloid CNS deposits were assessed by 18F- flutemetamol PET/CT examination utilising relative z scores with pons as reference.

Results: Expectedly, all Alzheimer patients had an clearly increased global composite z score above 2.0 compared with 55% of the ATTRv patients. There was an increased local uptake corresponding to cerebellum in 12 ATTRv patients compared to only one in the AD group (fig 1). Four of these ATTRv patients had a global composite z score within the normal range. No correlation between duration after 9 years and amyloid CNS deposition was noted.

Conclusion: Amyloid deposition within the brain after long-standing ATTRv amyloidosis is increased and is often noted in the cerebellum. However, not all patient display amyloid CNS deposition, thus, additional causes for CNS complications should always be considered.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-161913 (URN)10.1111/ene.14018 (DOI)000474481001092 ()
Conference
5th Congress of the European Academy of Neurology (EAN), June 29 – July 2, 2019, Oslo, Norway
Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-11-28Bibliographically approved
Pilebro, B., Arvidsson, S., Lindqvist, P., Sundström, T., Westermark, P., Antoni, G., . . . Sörensen, J. (2018). Positron emission tomography (PET) utilizing Pittsburgh compound B (PIB) for detection of amyloid heart deposits in hereditary transthyretin amyloidosis (ATTR). Journal of Nuclear Cardiology, 25(1), 240-248
Open this publication in new window or tab >>Positron emission tomography (PET) utilizing Pittsburgh compound B (PIB) for detection of amyloid heart deposits in hereditary transthyretin amyloidosis (ATTR)
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2018 (English)In: Journal of Nuclear Cardiology, ISSN 1071-3581, E-ISSN 1532-6551, Vol. 25, no 1, p. 240-248Article in journal (Refereed) Published
Abstract [en]

Background: DPD scintigraphy has been advocated for imaging cardiac amyloid in ATTR amyloidosis. PET utilizing 11C-Pittsburgh compound B (PIB) is the gold standard for imaging brain amyloid in Alzheimer’s disease. PIB was recently shown to identify cardiac amyloidosis in both AL and ATTR amyloidosis. In the ATTR population, two types of amyloid fibrils exist, one containing fragmented and full-length TTR (type A) and the other only full-length TTR (type B). The aim of this study was to further evaluate PIB-PET in patients with hereditary ATTR amyloidosis.

Methods: Ten patients with biopsy-proven V30M ATTR amyloidosis and discrete or no signs of cardiac involvement were included. Patients were grouped according to TTR-fragmentation. All underwent DPD scintigraphy, echocardiography, and PIB-PET. A left ventricular PIB-retention index (PIB-RI) was established and compared to five normal volunteers.

Results: PIB-RI was increased in all patients (P < 0.001), but was significantly higher in type B than in type A (0.129 ± 0.041 vs 0.040 ± 0.006 min−1, P = 0.009). Cardiac DPD uptake was elevated in group A and absent in group B.

Conclusion: PIB-PET, in contrast to DPD scintigraphy, has the potential to specifically identify cardiac amyloid depositions irrespective of amyloid fibril composition. The heart appears to be a target organ for amyloid deposition in ATTR amyloidosis.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Cardiomyopathy, amyloidosis, Pittsburgh compound B
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-127300 (URN)10.1007/s12350-016-0638-5 (DOI)000423585200038 ()27645889 (PubMedID)2-s2.0-84988421982 (Scopus ID)
Available from: 2016-11-07 Created: 2016-11-07 Last updated: 2019-05-21Bibliographically approved
Englund, H., Lidén K., K., Lind, T., Sundström, T. & Karling, P. (2017). Radiation exposure in patients with inflammatory bowel disease and irritable bowel syndrome in the years 2001-2011. Scandinavian Journal of Gastroenterology, 52(3), 300-305
Open this publication in new window or tab >>Radiation exposure in patients with inflammatory bowel disease and irritable bowel syndrome in the years 2001-2011
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2017 (English)In: Scandinavian Journal of Gastroenterology, ISSN 0036-5521, E-ISSN 1502-7708, Vol. 52, no 3, p. 300-305Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: To compare cumulative ionizing radiation in patients with inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) for the years 2001-2011. To study how radiation exposure change over time in patients with newly diagnosed IBD and factors associated with radiation exposure.

MATERIAL AND METHODS: All radiological investigations performed between 1 January 2001 and 31 December 2011 were retrospectively recorded in patients with Crohn's disease (CD) (n = 103), ulcerative colitis (UC) (n = 304) and IBS (n = 149). Analyses were done with Mann-Whitney and Chi-Square test.

RESULTS: The median total cumulative radiation exposure in mSv for CD (20.0, inter quartile range (IQR) 34.8), UC (7.01, IQR 23.8), IBS (2.71, IQR 9.15) and the proportion of patients who had been exposed for more than 50 mSv during the study period (CD 19%, UC 11%, IBS 3%) were significantly higher in the patients with CD compared to patients with UC (p < .001) and IBS (p < .001), respectively. In turn, patients with UC had significantly higher doses than patients with IBS (p = .005). Risk factors for radiation exposure were female gender (CD), early onset (UC), ileocolonic location (CD), previous surgery (CD and UC), depression (IBS) and widespread pain (IBS). In newly diagnosed CD, there was a significant decline in median cumulative radiation dose in mSv (17.2 vs. 12.0; p = .048) during the study period.

CONCLUSIONS: Patients with CD are at greatest risk for high cumulative radiation exposure, but there is a decline in exposure during the late 2000s. Non-colectomized patients with UC and patients with IBS have a relatively low risk of cumulative radiation exposure.

Keywords
IBD-clinical, small-intestinal disorders, functional disorders, computer-technology, colonic disorders
National Category
Gastroenterology and Hepatology
Identifiers
urn:nbn:se:umu:diva-128592 (URN)10.1080/00365521.2016.1252945 (DOI)000392488800008 ()27832710 (PubMedID)
Available from: 2016-12-07 Created: 2016-12-07 Last updated: 2019-05-17Bibliographically approved
Pilebro, B., Suhr, O. B., Näslund, U., Westermark, P., Lindqvist, P. & Sundström, T. (2016). 99mTC-DPD uptake reflects amyloid fibril composition in hereditary transthyretin amyloidosis. Upsala Journal of Medical Sciences, 121(1), 17-24
Open this publication in new window or tab >>99mTC-DPD uptake reflects amyloid fibril composition in hereditary transthyretin amyloidosis
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2016 (English)In: Upsala Journal of Medical Sciences, ISSN 0300-9734, E-ISSN 2000-1967, Vol. 121, no 1, p. 17-24Article in journal (Refereed) Published
Abstract [en]

Aims In transthyretin amyloid (ATTR) amyloidosis various principal phenotypes have been described: cardiac, neuropathic, or a mixed cardiac and neuropathic. In addition, two different types of amyloid fibrils have been identified (type A and type B). Type B fibrils have thus far only been found in predominantly early-onset V30M and in patients carrying the Y114C mutation, whereas type A is noted in all other mutations currently examined as well as in wild-type ATTR amyloidosis. The fibril type is a determinant of the ATTR V30M disease phenotype. Tc-99m-DPD scintigraphy is a highly sensitive method for diagnosing heart involvement in ATTR amyloidosis. The objective of this study was to determine the relationship between ATTR fibril composition and Tc-99m-DPD scintigraphy outcome in patients with biopsy-proven ATTR amyloidosis. Methods Altogether 55 patients with biopsy-proven diagnosis of ATTR amyloidosis and amyloid fibril composition determined were examined by Tc-99m-DPD scintigraphy. The patients were grouped and compared according to their type of amyloid fibrils. Cardiovascular evaluation included ECG, echocardiography, and cardiac biomarkers. The medical records were scrutinized to identify subjects with hypertension or other diseases that have an impact on cardiac dimensions. Results A total of 97% with type A and none of the patients with type B fibrils displayed Tc-99m-DPD uptake at scintigraphy (p < 0.001). Findings from analyses of cardiac biomarkers, ECG, and echocardiography, though significantly different, could not differentiate between type A and B fibrils in individual patients. Conclusion In ATTR amyloidosis, the outcome of Tc-99m-DPD scintigraphy is strongly related to the patients' transthyretin amyloid fibril composition.

Place, publisher, year, edition, pages
Taylor & Francis, 2016
Keywords
transthyretin, Amyloidosis hereditary, echocardiography, scintigraphy, amyloid cardiomyopathy
National Category
Clinical Medicine
Identifiers
urn:nbn:se:umu:diva-119085 (URN)10.3109/03009734.2015.1122687 (DOI)000372123700003 ()26849806 (PubMedID)
Available from: 2016-04-19 Created: 2016-04-11 Last updated: 2018-06-07Bibliographically approved
Wixner, J., Sundström, T., Karling, P., Anan, I. & Suhr, O. B. (2015). Outcome of gastric emptying and gastrointestinal symptoms after liver transplantation for hereditary transthyretin amyloidosis. BMC Gastroenterology, 15, Article ID 51.
Open this publication in new window or tab >>Outcome of gastric emptying and gastrointestinal symptoms after liver transplantation for hereditary transthyretin amyloidosis
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2015 (English)In: BMC Gastroenterology, ISSN 1471-230X, E-ISSN 1471-230X, Vol. 15, article id 51Article in journal (Refereed) Published
Abstract [en]

Background: Hereditary transthyretin amyloid (ATTR) amyloidosis is a rare but fatal autosomal dominant condition that is present all over the world. A liver transplantation has been shown to halt the progress of the disease in selected patients and is currently considered to be the standard treatment. Gastrointestinal manifestations are common in hereditary ATTR amyloidosis and are important for the patients' morbidity and mortality. The aim of this study was to evaluate the long-term outcome of gastric emptying, gastrointestinal symptoms and nutritional status after liver transplantation for the disease.

Methods: Swedish patients with hereditary ATTR amyloidosis transplanted between 1990 and 2012 were included. A standardized method for measuring gastric emptying with a Tc-99m-labelled meal followed by scintigraphy was utilized. Validated questionnaires were used to assess gastrointestinal symptoms and the modified body mass index (mBMI), in which BMI is multiplied by s-albumin, was used to evaluate nutritional status. Non-parametrical statistical tests were used.

Results: Gastric emptying rates and nutritional statuses were evaluated approximately eight months before and two and five years after liver transplantation, whereas gastrointestinal symptoms were assessed in median nine months before and two and nine years after transplantation. No significant change was found in gastric emptying (median half-time 137 vs. 132 vs. 125 min, p = 0.52) or nutritional status (median mBMI 975 vs. 991 vs. 973, p = 0.75) after transplantation. Gastrointestinal symptom scores, however, had increased significantly over time (median score 7 vs. 10 vs. 13, p < 0.01).

Conclusions: Gastric emptying and nutritional status were maintained after liver transplantation for hereditary ATTR amyloidosis, although gastrointestinal symptom scores had increased over time.

Keywords
Amyloidosis, Hereditary, Functional gastrointestinal disorders, Gastric emptying, Transplantation, Liver, Transthyretin
National Category
Gastroenterology and Hepatology
Identifiers
urn:nbn:se:umu:diva-103731 (URN)10.1186/s12876-015-0284-4 (DOI)000353687200001 ()25908211 (PubMedID)
Note

Originally included in thesis in manuscript form.

Available from: 2015-06-09 Created: 2015-05-28 Last updated: 2018-06-07Bibliographically approved
Strandberg, S., Karlsson, C. T., Sundström, T., Ögren, M., Ögren, M., Axelsson, J. & Riklund, K. (2014). 11C-acetate PET/CT in pre-therapeutic lymph node staging in high-risk prostate cancer patients and its influence on disease management: a retrospective study. EJNMMI Research, 4(55), 1-9
Open this publication in new window or tab >>11C-acetate PET/CT in pre-therapeutic lymph node staging in high-risk prostate cancer patients and its influence on disease management: a retrospective study
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2014 (English)In: EJNMMI Research, ISSN 2191-219X, E-ISSN 2191-219X, Vol. 4, no 55, p. 1-9Article in journal (Refereed) Published
Abstract [en]

Background: Radiation treatment with simultaneous integrated boost against suspected lymph node metastases may be a curative therapeutic option in patients with high-risk prostate cancer (> 15% estimated risk of pelvic lymph node metastases according to the Cagiannos nomogram). C-11-acetate positron emission tomography/computed tomography (PET/CT) can be used for primary staging as well as for detection of suspected relapse of prostate cancer. The aims of this study were to evaluate the association between positive C-11-acetate PET/CT findings and the estimated risk of pelvic lymph node metastases and to assess the impact of C-11-acetate PET/CT on patient management in high-risk prostate cancer patients. Methods: Fifty consecutive prostate cancer patients referred for primary staging with C-11-acetate PET/CT prior to radiotherapy with curative intention were enrolled in this retrospective study. Results: All patients showed increased C-11-acetate uptake in the prostate. Pelvic lymph node uptake was seen in 42% (21/50) of the patients, with positive external iliac lymph nodes in 71% (15/21) of these. The overall observed proportion of PET/CT-positive pelvic lymph nodes at patient level was higher than the average estimated risk, especially in low-risk groups (< 15%). There was a significant association between observed proportion and estimated risk of pelvic lymph node metastases in groups with <= 45 and >45% estimated risk. Treatment strategy was altered due to C-11-acetate PET/CT findings in 43% (20/47) of the patients. Conclusions: The observed proportion of C-11-acetate PET/CT findings suggestive of locoregional metastases was higher than the estimated risk, suggesting that the Cagiannos nomogram underestimates the risk for metastases. The imaging results with C-11-acetate PET/CT have a considerable impact on patient management.

Place, publisher, year, edition, pages
Springer, 2014
Keywords
Prostatic neoplasms, PET/CT, C-11-acetate, Neoplasm staging, Lymphatic metastasis
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-106804 (URN)10.1186/s13550-014-0055-1 (DOI)000358122600001 ()26116118 (PubMedID)
Available from: 2015-08-18 Created: 2015-08-07 Last updated: 2018-06-07Bibliographically approved
Larsson, A., Holmberg, D., Sundström, T., Axelsson, J. & Riklund, K. (2013). Optimal contrast as a function of noise for Butterworth filtering of 111 In-pentetreotide SPECT when using model-based compensation. In: 2013 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC): . Paper presented at 60th IEEE Nuclear Science Symposium (NSS) / Medical Imaging Conference (MIC) / 20th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors, OCT 27-NOV 02, 2013, Seoul, SOUTH KOREA.
Open this publication in new window or tab >>Optimal contrast as a function of noise for Butterworth filtering of 111 In-pentetreotide SPECT when using model-based compensation
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2013 (English)In: 2013 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC), 2013Conference paper, Published paper (Refereed)
Abstract [en]

In 111 In-pentetreotide SPECT, it can be difficult to detect small tumors because of low spatial resolution and high noise levels. For an efficient cancer treatment, it is however important to detect the tumors at an early stage. The aim of this study was to perform optimization of Butterworth post-filtering of In-111-pentetreotide SPECT, with regard to small tumor detection in the liver. All images were reconstructed with model-based OSEM reconstruction. Two collimators are evaluated, the extended low-energy general-purpose (ELEGP) and the medium-energy general-purpose (MEGP) collimator. The raw-data projection images are produced using Monte Carlo simulations of an anthropomorphic phantom with realistic In-111-pentetreotide uptake, including seven spherical tumors in the liver. Evaluation was performed using tumor contrast as a function of background noise. According to the results, the detection of the smallest tumors is facilitated by not applying a filter. For somewhat larger tumors, a Butterworth filter of critical frequencies of 0.5-0.6 cm(-1) and an order of 10-12 is more appropriate. ELEGP proved to be better than MEGP for small tumor detection. The study is a continuation of a previous project where collimator choice, acquisition time, number of projection angles and OSEM settings were studied for the same geometry.

National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-129851 (URN)10.1109/NSSMIC.2013.6829275 (DOI)000347163501089 ()978-1-4799-0534-8 (ISBN)
Conference
60th IEEE Nuclear Science Symposium (NSS) / Medical Imaging Conference (MIC) / 20th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors, OCT 27-NOV 02, 2013, Seoul, SOUTH KOREA
Available from: 2017-01-10 Created: 2017-01-09 Last updated: 2018-06-09Bibliographically approved
Wallstén, E., Axelsson, J., Sundström, T., Riklund, K. & Larsson, A. (2013). Subcentimeter Tumor Lesion Delineation for High-Resolution 18F-FDG PET Images: Optimizing Correction for Partial-Volume Effects.. Journal of Nuclear Medicine Technology, 41(2), 85-91
Open this publication in new window or tab >>Subcentimeter Tumor Lesion Delineation for High-Resolution 18F-FDG PET Images: Optimizing Correction for Partial-Volume Effects.
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2013 (English)In: Journal of Nuclear Medicine Technology, ISSN 0091-4916, E-ISSN 1535-5675, Vol. 41, no 2, p. 85-91Article in journal (Refereed) Published
Abstract [en]

In PET, partial-volume effects cause errors in estimation of size and activity for small objects with radiopharmaceutical uptake. Recent methods for image reconstruction, compared with traditional reconstruction techniques, include algorithms for resolution recovery that result in images with higher resolution and enable quantification of size and activity of smaller objects. The purpose of this study was to evaluate a combination of 2 algorithms for volume delineation and partial-volume correction on uptake volumes smaller than 0.7 mL using image reconstruction algorithms with and without resolution recovery.

METHODS: Volumes of interests (VOIs) were delineated using a threshold intensity calculated as a weighted sum of tumor and background intensities. These VOIs were used for calculating correction factors by convolving a tumor mask with the system point-spread function. The methods algorithms were evaluated using a phantom constructed from 5 small different-sized balloons filled with (18)F-FDG in background activity. Six different backgrounds were used. Data were acquired using a PET/CT scanner, and the images were reconstructed using 2 iterative algorithms, one of which used a resolution recovery algorithm.

RESULTS: For the images reconstructed using the resolution recovery algorithm, the method for volume delineation resulted in VOI sizes that were correct within 1 SD for all balloons of a volume of 0.35 mL (equivalent diameter, 8.8 mm) and larger, in all backgrounds. For the images reconstructed without resolution recovery, the VOI sizes were background-dependent and generally less accurate. Correct volume delineations generally led to accurate activity estimates.

CONCLUSION: The algorithms tested on the phantom developed for this study could, for this PET camera and these reconstruction algorithms, be used for accurate volume delineation and activity quantification of lesions 0.35 mL and larger.

Place, publisher, year, edition, pages
Society of Nuclear Medicine and Molecular Imaging, 2013
Keywords
PET, partial-volume effects, partial volume correction, volume delineation, resolution recovery
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:umu:diva-76744 (URN)10.2967/jnmt.112.117234 (DOI)23658206 (PubMedID)
Available from: 2013-07-12 Created: 2013-07-12 Last updated: 2018-06-08Bibliographically approved
Mähler, E., Sundström, T., Axelsson, J. & Larsson, A. (2012). Detecting small liver tumors with In-111-Pentetreotide SPECT-A Collimator study based on Monte Carlo simulations. IEEE Transactions on Nuclear Science, 59(1), 47-53
Open this publication in new window or tab >>Detecting small liver tumors with In-111-Pentetreotide SPECT-A Collimator study based on Monte Carlo simulations
2012 (English)In: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 59, no 1, p. 47-53Article in journal (Refereed) Published
Abstract [en]

In In-111- pentetreotide single-photon emission computed tomography (SPECT), the tumor-to-background-uptake ratio is generally high. The noise is, however, also usually on a high level, and in combination with the low spatial resolution of SPECT, this may lead to difficulties in the detection of small tumors. This is especially the case in regions with a relatively high background activity, such as in the liver, which is a common region for somatostatin-positive metastases. Visually detecting the small tumors is important for a successful treatment of the cancer disease. In this paper, we compare three different parallel-hole collimators for In-111-pentetreotide SPECT regarding contrast as a function of image noise for a phantom simulating small tumors in liver background. The corresponding contrast-to-noise ratios are also presented. All raw-data projections are produced using Monte Carlo simulations. The collimators are of type low-energy general-purpose (LEGP), extended LEGP (ELEGP), and medium-energy general-purpose (MEGP). Reconstructions were performed with OSEM both with and without model-based compensation. Of the investigated collimators, the ELEGP collimator proved to be the most optimal for the smallest tumors, both with and without model-based compensation included in the reconstruction. It is also shown that model-based compensation outperforms the conventional reconstruction technique.

Place, publisher, year, edition, pages
IEEE, 2012
Keywords
In-111-pentetreotide, liver tumor, model-based compensation, single-photon emission computed tomography (SPECT)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:umu:diva-53115 (URN)10.1109/TNS.2011.2172815 (DOI)000300422500007 ()
Available from: 2012-03-14 Created: 2012-03-13 Last updated: 2018-06-08Bibliographically approved
Holmberg, D., Sundström, T., Riklund, K., Axelsson, J., Ljungberg, M. & Larsson, A. (2012). Reducing Scanning Time to 50% for In-111 Pentetreotide SPECT When Using Model-Based Compensation. In: B. Yu (Ed.), 2012 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE RECORD (NSS/MIC): . Paper presented at IEEE Nuclear Science Symposium / Medical Imaging Conference Record (NSS/MIC) / 19th Room-Temperature Semiconductor X-ray and Gamma-ray Detector Workshop, OCT 29-NOV 03, 2012, Anaheim, CA (pp. 2946-2949).
Open this publication in new window or tab >>Reducing Scanning Time to 50% for In-111 Pentetreotide SPECT When Using Model-Based Compensation
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2012 (English)In: 2012 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE RECORD (NSS/MIC) / [ed] B. Yu, 2012, p. 2946-2949Conference paper, Published paper (Refereed)
Abstract [en]

In In-111-pentetreotide SPECT, it can be difficult to detect small tumors because of high noise levels and low spatial resolution. The aim of this study was to perform optimization of tumor detection in the liver, with regards to the acquisition and reconstruction protocol for In-111-pentetreotide SPECT with model-based compensation included in the OSEM reconstruction. We were also interested in the effect of performing the examination in half of the time or with half the administered activity. Image reconstruction without model-based compensation was also included for comparison. The study concentrates on the acquired number of projections and the subset size in the OSEM reconstruction, and evaluates contrast as a function of noise for a range of OSEM iterations. The raw-data projections are produced using Monte Carlo simulations of a patient-like anthropomorphic phantom with realistic In-111 pentetreotide uptake, including spherical tumors in the liver. Two collimators are evaluated, the extended low-energy general-purpose (ELEGP) and the medium-energy general-purpose (MEGP) collimator. ELEGP proved to be a better collimator when using model-based compensation. The results also indicate that a relatively low number of subsets is advantageous, and that 60 projection angles or even lower is a better choice than 120. For both collimators the time-reduced scan including model-based compensation was better compared to the full-time reconstructions without model-based compensation.

Series
IEEE Nuclear Science Symposium Conference Record, ISSN 1082-3654
National Category
Physical Sciences Engineering and Technology
Identifiers
urn:nbn:se:umu:diva-84149 (URN)000326814203010 ()978-1-4673-2030-6 (ISBN)
Conference
IEEE Nuclear Science Symposium / Medical Imaging Conference Record (NSS/MIC) / 19th Room-Temperature Semiconductor X-ray and Gamma-ray Detector Workshop, OCT 29-NOV 03, 2012, Anaheim, CA
Available from: 2013-12-17 Created: 2013-12-16 Last updated: 2018-06-08Bibliographically approved
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