| 1. |
- Hindorf, Cecilia, et al.
(författare)
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Importance of correct patient positioning in myocardial perfusion SPECT when using a CZT camera.
- 2014
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Ingår i: Journal of Nuclear Cardiology. - : Springer Science and Business Media LLC. - 1532-6551 .- 1071-3581. ; 21:4, s. 695-702
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Tidskriftsartikel (refereegranskat)abstract
- Myocardial perfusion single photon emission computed tomography (MPS) is one of the most widely used diagnostic methods in patients with suspected ischemic heart disease (IHD). Recently, a novel technique based on cadmium-zinc-telluride (CZT) detectors, pinhole collimators, and a stationary gantry was introduced for MPS. The aim of this work was to investigate how patient positioning affects the reconstructed MPS images using this novel technique.
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| 2. |
- Oddstig, Jenny, 1978, et al.
(författare)
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Inhomogeneous activity distribution of (177)Lu-DOTA (0)-Tyr (3)-octreotate and effects on somatostatin receptor expression in human carcinoid GOT1 tumors in nude mice.
- 2012
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Ingår i: Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine. - : Springer Science and Business Media LLC. - 1423-0380. ; 33:1, s. 229-239
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the activity distribution in neouroendocrine tumors after diagnostic, or therapeutic, amounts of [(177)Lu-DOTA(0)-Tyr(3)]-octreotate and to investigate how the activity distribution influences the absorbed dose. Furthermore, the activity distribution of a second administration of radiolabeled octreotate was studied. Nude mice with subcutaneously grown human midgut carcinoid (GOT1) were injected intravenously with different amounts of (177)Lu-octreotate. At different time points thereafter (4h to 13days), a second injection of [(111)In-DOTA(0)-Tyr(3)]-octreotate was given to estimate the somatostatin receptor (sstr) expression. The activity distribution in the tumors was then determined. Monte Carlo simulations with PENELOPE were performed for dosimetry. Fifty-one out of 58 investigated tumors showed a lower activity concentration in the peripheral part than in the central part of the tumor. The amount of activity injected, or time after administration, did neither influence the relative activity nor the sstr distribution in the tumor. After an initial down-regulation (at 4-24h), there was an up-regulation of sstr (1.5-2 times, at 7-14days). Monte Carlo simulations demonstrated an inhomogeneous absorbed dose distribution in the tumor using (177)Lu, with twice as high absorbed dose centrally than peripherally. The high activity concentration centrally and the up-regulation of sstr demonstrated will facilitate fractionated therapy using radiolabeled somatostatin analogues if similar results will be obtained also in patients. The inhomogeneous activity distribution in the tumor has to be taken into account when the absorbed dose distribution in tumor is calculated.
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| 3. |
- Oddstig, Jenny, 1978, et al.
(författare)
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Radiation Induces Up-Regulation of Somatostatin Receptors 1, 2, and 5 in Small Cell Lung Cancer In Vitro Also at Low Absorbed Doses.
- 2011
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Ingår i: Cancer biotherapy & radiopharmaceuticals. - : Mary Ann Liebert Inc. - 1557-8852 .- 1084-9785. ; 26:6
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Background: Radiation can be used to up-regulate the expression of the somatostatin receptor (sstr) subtype 2 in small cell lung cancer (SCLC) cells at absorbed doses of 2?8 Gy. Increased sstr expression results in increased binding of radiolabeled somatostatin analogs to the tumor cell, which enhances the efficacy of systemic radionuclide therapy. The aim of this study was to determine if lower absorbed doses could up-regulate sstr2 expression, and possibly influence other sstr subtypes. Methods: Human H69 SCLC cells were irradiated with an absorbed dose of 0.12?6.0 Gy and the sstr mRNA expression 3 days after irradiation was measured by quantitative real-time polymerase chain reaction for sstr1?5. At the same time point was the binding of [(177)Lu]-DOTA(0)-Tyr(3)-octreotate to the cells measured after irradiation to an absorbed dose of 0.12?2.0 Gy and compared to the binding to nonirradiated cells. Results: mRNA expression of sstr1, sstr2, and sstr5 was increased by a factor of 1.5?2 in cells irradiated with absorbed doses?4 Gy and the binding of [(177)Lu]-DOTA(0)-Tyr(3)-octreotate was, accordingly, 2?3 times higher to irradiated cells for all absorbed doses, except 0.25 Gy. Conclusion: The binding of [(177)Lu]-DOTA(0)-Tyr(3)-octreotate was increased after radiation exposure. This increase was observed at low absorbed doses in parallel with up-regulation of sstr1, sstr2, and sstr5 mRNA.
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| 4. |
- Oddstig, Jenny, et al.
(författare)
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Reduced administered activity, reduced acquisition time, and preserved image quality for the new CZT camera.
- 2013
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Ingår i: Journal of Nuclear Cardiology. - : Springer Science and Business Media LLC. - 1532-6551 .- 1071-3581. ; 20:1, s. 38-44
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: For a 1-day myocardial perfusion SPECT (MPS) the recommendations for administered activity stated in the EANM guidelines results in an effective dose of up to 16 mSv per patient. Recently, a gamma camera system, based on cadmium zinc telluride (CZT) technology, was introduced. This technique has the potential to reduce the effective dose and scan time compared to the conventional NaI gamma camera. The aim of this study was to investigate if the effective dose can be reduced with a preserved image quality using CZT technology in MPS. METHODS: In total, 150 patients were included in the study. All underwent a 1-day (99m)Tc-tetrofosmin stress-rest protocol and were divided into three subgroups (n = 50 in each group) with 4, 3, and 2.5 MBq/kg body weight of administered activity in the stress examination, respectively. The acquisition time was increased in proportion to the decrease in administered activity. All examinations were analyzed for image quality by visual grading on a 4-point scale (1 = poor, 2 = adequate, 3 = good, 4 = excellent), by two expert readers. RESULTS: The total effective dose (stress + rest) decreased from 9.3 to 5.8 mSv comparing 4 to 2.5 MBq/kg body weight. For the patients undergoing stress examination only (35%) the effective dose, administrating 2.5 MBq/kg, was 1.4 mSv. The image acquisition times for 2.5 MBq/kg body weight were 475 and 300 seconds (stress and rest) compared to 900 seconds for each when using conventional MPS. The average image quality was 3.7 ± 0.5, 3.8 ± 0.5, and 3.8 ± 0.4 for the stress images and 3.5 ± 0.6, 3.6 ± 0.6, and 3.5 ± 0.6 for the rest images and showed no statistically significant difference (P = .62) among the 4, 3, and 2.5 MBq/kg groups. CONCLUSIONS: The new CZT technology can be used to considerably decrease the effective dose and acquisition time for MPS with preserved high image quality.
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| 5. |
- Söderberg, Marcus, et al.
(författare)
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Evaluation of image reconstruction methods for 123I-MIBG-SPECT: a rank-order study.
- 2012
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Ingår i: Acta Radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 53:7, s. 778-784
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Tidskriftsartikel (refereegranskat)abstract
- Background: There is an opportunity to improve the image quality and lesion detectability in single photon emission computed tomography (SPECT) by choosing an appropriate reconstruction method and optimal parameters for the reconstruction. Purpose: To optimize the use of the Flash 3D reconstruction algorithm in terms of equivalent iteration (EI) number (number of subsets times the number of iterations) and to compare with two recently developed reconstruction algorithms ReSPECT and orthogonal polynomial expansion on disc (OPED) for application on (123)I-metaiodobenzylguanidine (MIBG)-SPECT. Material and Methods: Eleven adult patients underwent SPECT 4 h and 14 patients 24 h after injection of approximately 200 MBq (123)I-MIBG using a Siemens Symbia T6 SPECT/CT. Images were reconstructed from raw data using the Flash 3D algorithm at eight different EI numbers. The images were ranked by three experienced nuclear medicine physicians according to their overall impression of the image quality. The obtained optimal images were then compared in one further visual comparison with images reconstructed using the ReSPECT and OPED algorithms.ResultsThe optimal EI number for Flash 3D was determined to be 32 for acquisition 4 h and 24 h after injection. The average rank order (best first) for the different reconstructions for acquisition after 4 h was: Flash 3D(32) > ReSPECT > Flash 3D(64) > OPED, and after 24 h: Flash 3D(16) > ReSPECT > Flash 3D(32) > OPED. A fair level of inter-observer agreement concerning optimal EI number and reconstruction algorithm was obtained, which may be explained by the different individual preferences of what is appropriate image quality. Conclusion: Using Siemens Symbia T6 SPECT/CT and specified acquisition parameters, Flash 3D(32) (4 h) and Flash 3D(16) (24 h), followed by ReSPECT, were assessed to be the preferable reconstruction algorithms in visual assessment of (123)I-MIBG images.
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