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Shibutani T, Onoguchi M, Kanno T, Kinuya S. Influence of spill-over for 99mTc images and the effect of scatter correction for dual-isotope simultaneous acquisition with 99mTc and 18F using small-animal SPECT-PET/CT system. Phys Eng Sci Med 2024; 47:135-142. [PMID: 37902935 DOI: 10.1007/s13246-023-01348-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 10/16/2023] [Indexed: 11/01/2023]
Abstract
A dual-isotope simultaneous acquisition (DISA) of 99mTc and 18F affects the image quality of 99mTc by crosstalk and spill-over from 18F. We demonstrated the influence of spill-over and crosstalk on image quality and its correction effect for DISA SPECT with 99mTc and 18F. A fillable cylindrical chamber of 30 mm with NEMA-NU4 image quality phantom was filled with 99mTc only or a mixed 99mTc and 18F solution (C100). Two small-region chambers were filled with 99mTc only or a mixed 99mTc and 18F solution made at half the radioactivity concentration of C100 (C50) and non-radioactive water (C0). The 18F/99mTc ratio for DISA was set at approximately 0.4-12. Two types of 99mTc transverse images with and without scatter correction (SC and nonSC) were created. The 99mTc images of single-isotope acquisition (SIA) were created as a reference. The DISA/SIA ratio and contrast of 99mTc were compared between SIA and DISA. Although the DISA/SIA ratios with nonSC of C100, C50 and C0 gradually increased with increasing 18F/99mTc ratio, it was nearly constant by SC. The contrasts of C100 and C50 were similar to a reference value for both nonSC and SC. In conclusion, DISA images showed lower image quality as the 18F/99mTc ratio increased. The image quality in hot-spot regions such as C100 and C50 was improved by SC, whereas cold-spot regions such as C0 could not completely remove the influence of spill-over even with SC.
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Affiliation(s)
- Takayuki Shibutani
- Department of Quantum Medical Technology, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
- Department of Quantum Medical Technology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
| | - Masahisa Onoguchi
- Department of Quantum Medical Technology, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
- Department of Quantum Medical Technology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan.
| | - Takayuki Kanno
- Department of Quantum Medical Technology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
- Department of Radiological Technology, Nagoya University Hospital, Nagoya, Japan
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Seigo Kinuya
- Department of Nuclear Medicine, Kanazawa University Hospital, Kanazawa, Japan
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Miwa K, Nemoto R, Masuko H, Yamao T, Kobayashi R, Miyaji N, Inoue K, Onodera H. Evaluation of quantitative accuracy among different scatter corrections for quantitative bone SPECT/CT imaging. PLoS One 2022; 17:e0269542. [PMID: 35666737 PMCID: PMC9170091 DOI: 10.1371/journal.pone.0269542] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 05/23/2022] [Indexed: 11/19/2022] Open
Abstract
Although scatter correction improves SPECT image contrast and thus image quality, the effects of quantitation accuracy under various conditions remain unclear. The present study aimed to empirically define the conditions for the optimal scatter correction of quantitative bone SPECT/CT images. Scatter correction was performed by applying dual and triple energy windows (DEW and TEW) with different sub-energy window widths, and effective scatter source estimation (ESSE) to CT-based scatter correction. Scattered radiation was corrected on images acquired using a triple line source (TLSP) phantom and an uniform cylinder phantom. The TLSP consisted of a line source containing 74.0 MBq of 99mTc in the middle, and a background component containing air, water or a K2HPO4 solution with a density equivalent to that of bone. The sum of all pixels in air, water and the K2HPO4 solution was measured on SPECT images. Scatter fraction (SF) and normalized mean square error (NMSE) based on counts from the air background as a reference were then calculated to assess quantitative errors due to scatter correction. The uniform cylinder phantom contained the same K2HPO4 solution and 222.0 MBq of 99mTc. The coefficient of variation (CV) was calculated from the count profile of this phantom to assess the uniformity of SPECT images across scatter correction under various conditions. Both SF and NMSE in SPECT images of phantoms containing water in the background were lower at a TEW sub-window of 3% (TEW3%), than in other scatter corrections, whereas those in K2HPO4 were lower at a DEW sub-window of 20% (DEW20%). Larger DEW and smaller TEW sub-energy windows allowed more effective correction. The CV of the uniform cylinder phantom, DEW20%, was inferior to all other tested scatter corrections. The quantitative accuracy of bone SPECT images substantially differed according to the method of scatter correction. The optimal scatter correction for quantitative bone SPECT was DEW20% (k = 1), but at the cost of slightly decreased image uniformity.
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Affiliation(s)
- Kenta Miwa
- Department of Radiological Sciences, School of Health Sciences, Fukushima Medical University, Fukushima, Japan
- Department of Radiological Sciences, School of Health Sciences, International University of Health and Welfare, Tochigi, Japan
- * E-mail:
| | - Reo Nemoto
- Department of Radiological Sciences, School of Health Sciences, International University of Health and Welfare, Tochigi, Japan
| | - Hirotsugu Masuko
- Department of Radiological Sciences, School of Health Sciences, International University of Health and Welfare, Tochigi, Japan
| | - Tensho Yamao
- Department of Radiological Sciences, School of Health Sciences, Fukushima Medical University, Fukushima, Japan
- Department of Radiological Sciences, School of Health Sciences, International University of Health and Welfare, Tochigi, Japan
| | - Rinya Kobayashi
- Department of Radiological Sciences, School of Health Sciences, International University of Health and Welfare, Tochigi, Japan
| | - Noriaki Miyaji
- Department of Nuclear Medicine, Cancer Institute Hospital of Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Kosuke Inoue
- Department of Radiological Sciences, School of Health Sciences, International University of Health and Welfare, Tochigi, Japan
| | - Hiroya Onodera
- Department of Radiological Sciences, School of Health Sciences, International University of Health and Welfare, Tochigi, Japan
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Liu Z, Moon HS, Li Z, Laforest R, Perlmutter JS, Norris SA, Jha AK. A tissue‐fraction estimation‐based segmentation method for quantitative dopamine transporter SPECT. Med Phys 2022; 49:5121-5137. [PMID: 35635327 PMCID: PMC9703616 DOI: 10.1002/mp.15778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 04/25/2022] [Accepted: 05/16/2022] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Quantitative measures of dopamine transporter (DaT) uptake in caudate, putamen, and globus pallidus (GP) derived from dopamine transporter-single-photon emission computed tomography (DaT-SPECT) images have potential as biomarkers for measuring the severity of Parkinson's disease. Reliable quantification of this uptake requires accurate segmentation of the considered regions. However, segmentation of these regions from DaT-SPECT images is challenging, a major reason being partial-volume effects (PVEs) in SPECT. The PVEs arise from two sources, namely the limited system resolution and reconstruction of images over finite-sized voxel grids. The limited system resolution results in blurred boundaries of the different regions. The finite voxel size leads to TFEs, that is, voxels contain a mixture of regions. Thus, there is an important need for methods that can account for the PVEs, including the TFEs, and accurately segment the caudate, putamen, and GP, from DaT-SPECT images. PURPOSE Design and objectively evaluate a fully automated tissue-fraction estimation-based segmentation method that segments the caudate, putamen, and GP from DaT-SPECT images. METHODS The proposed method estimates the posterior mean of the fractional volumes occupied by the caudate, putamen, and GP within each voxel of a three-dimensional DaT-SPECT image. The estimate is obtained by minimizing a cost function based on the binary cross-entropy loss between the true and estimated fractional volumes over a population of SPECT images, where the distribution of true fractional volumes is obtained from existing populations of clinical magnetic resonance images. The method is implemented using a supervised deep-learning-based approach. RESULTS Evaluations using clinically guided highly realistic simulation studies show that the proposed method accurately segmented the caudate, putamen, and GP with high mean Dice similarity coefficients of ∼ 0.80 and significantly outperformed ( p < 0.01 $p < 0.01$ ) all other considered segmentation methods. Further, an objective evaluation of the proposed method on the task of quantifying regional uptake shows that the method yielded reliable quantification with low ensemble normalized root mean square error (NRMSE) < 20% for all the considered regions. In particular, the method yielded an even lower ensemble NRMSE of ∼ 10% for the caudate and putamen. CONCLUSIONS The proposed tissue-fraction estimation-based segmentation method for DaT-SPECT images demonstrated the ability to accurately segment the caudate, putamen, and GP, and reliably quantify the uptake within these regions. The results motivate further evaluation of the method with physical-phantom and patient studies.
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Affiliation(s)
- Ziping Liu
- Department of Biomedical Engineering Washington University St. Louis MO 63130 United States of America
| | - Hae Sol Moon
- Department of Biomedical Engineering Washington University St. Louis MO 63130 United States of America
| | - Zekun Li
- Department of Biomedical Engineering Washington University St. Louis MO 63130 United States of America
| | - Richard Laforest
- Mallinckrodt Institute of Radiology Washington University School of Medicine St. Louis MO 63110 United States of America
| | - Joel S. Perlmutter
- Mallinckrodt Institute of Radiology Washington University School of Medicine St. Louis MO 63110 United States of America
- Department of Neurology Washington University School of Medicine St. Louis MO 63110 United States of America
| | - Scott A. Norris
- Mallinckrodt Institute of Radiology Washington University School of Medicine St. Louis MO 63110 United States of America
- Department of Neurology Washington University School of Medicine St. Louis MO 63110 United States of America
| | - Abhinav K. Jha
- Department of Biomedical Engineering Washington University St. Louis MO 63130 United States of America
- Mallinckrodt Institute of Radiology Washington University School of Medicine St. Louis MO 63110 United States of America
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Sakai M, Parajuli RK, Kubota Y, Kubo N, Yamaguchi M, Nagao Y, Kawachi N, Kikuchi M, Arakawa K, Tashiro M. Crosstalk Reduction Using a Dual Energy Window Scatter Correction in Compton Imaging. SENSORS (BASEL, SWITZERLAND) 2020; 20:E2453. [PMID: 32357411 PMCID: PMC7249665 DOI: 10.3390/s20092453] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 04/14/2020] [Accepted: 04/23/2020] [Indexed: 11/17/2022]
Abstract
Compton cameras can simultaneously detect multi-isotopes; however, when simultaneous imaging is performed, crosstalk artifacts appear on the images obtained using a low-energy window. In conventional single-photon emission computed tomography, a dual energy window (DEW) subtraction method is used to reduce crosstalk. This study aimed to evaluate the effectiveness of employing the DEW technique to reduce crosstalk artifacts in Compton images obtained using low-energy windows. To this end, in this study, we compared reconstructed images obtained using either a photo-peak window or a scatter window by performing image subtraction based on the differences between the two images. Simulation calculations were performed to obtain the list data for the Compton camera using a 171 and a 511 keV point source. In the images reconstructed using these data, crosstalk artifacts were clearly observed in the images obtained using a 171 keV photo-peak energy window. In the images obtained using a scatter window (176-186 keV), only crosstalk artifacts were visible. The DEW method could eliminate the influence of high-energy sources on the images obtained with a photo-peak window, thereby improving quantitative capability. This was also observed when the DEW method was used on experimentally obtained images.
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Affiliation(s)
- Makoto Sakai
- Graduate School of Medicine, Gunma University Heavy Ion Medical Center, 3-39-22 Showa-Machi, Maebashi 371-8511, Japan
| | - Raj Kumar Parajuli
- Graduate School of Medicine, Gunma University Heavy Ion Medical Center, 3-39-22 Showa-Machi, Maebashi 371-8511, Japan
- Department of Molecular Imaging and Theranostics, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Anagawa 4-9-1, Inage, Chiba 263-8555, Japan
| | - Yoshiki Kubota
- Graduate School of Medicine, Gunma University Heavy Ion Medical Center, 3-39-22 Showa-Machi, Maebashi 371-8511, Japan
| | - Nobuteru Kubo
- Department of Radiation Oncology, Graduate School of Medicine, Gunma University, 3-39-22 Showa-Machi, Maebashi 371-8511, Japan
| | - Mitsutaka Yamaguchi
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki-Machi, Takasaki 370-1292, Japan
| | - Yuto Nagao
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki-Machi, Takasaki 370-1292, Japan
| | - Naoki Kawachi
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki-Machi, Takasaki 370-1292, Japan
| | - Mikiko Kikuchi
- Graduate School of Medicine, Gunma University Heavy Ion Medical Center, 3-39-22 Showa-Machi, Maebashi 371-8511, Japan
| | - Kazuo Arakawa
- Graduate School of Medicine, Gunma University Heavy Ion Medical Center, 3-39-22 Showa-Machi, Maebashi 371-8511, Japan
| | - Mutsumi Tashiro
- Graduate School of Medicine, Gunma University Heavy Ion Medical Center, 3-39-22 Showa-Machi, Maebashi 371-8511, Japan
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Esquinas PL, Rodríguez-Rodríguez C, Esposito TVF, Harboe J, Bergamo M, Celler A, Saatchi K, Sossi V, Häfeli UO. Dual SPECT imaging of 111In and 67Ga to simultaneously determine in vivo the pharmacokinetics of different radiopharmaceuticals: a quantitative tool in pre-clinical research. ACTA ACUST UNITED AC 2018; 63:235029. [DOI: 10.1088/1361-6560/aaef63] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Tsartsalis S, Tournier BB, Habiby S, Ben Hamadi M, Barca C, Ginovart N, Millet P. Dual-radiotracer translational SPECT neuroimaging. Comparison of three methods for the simultaneous brain imaging of D2/3 and 5-HT2A receptors. Neuroimage 2018; 176:528-540. [DOI: 10.1016/j.neuroimage.2018.04.063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 03/11/2018] [Accepted: 04/27/2018] [Indexed: 12/27/2022] Open
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Beijst C, de Keizer B, Lam MGEH, Janssens GO, Tytgat GAM, de Jong HWAM. A phantom study: Should 124 I-mIBG PET/CT replace 123 I-mIBG SPECT/CT? Med Phys 2017; 44:1624-1631. [PMID: 28273347 DOI: 10.1002/mp.12202] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 02/24/2017] [Accepted: 02/28/2017] [Indexed: 11/11/2022] Open
Abstract
PURPOSE The isotope 123 I is commonly labeled with meta-iodobenzylguanidine (mIBG) for imaging of neuroendocrine tumors, such as pheochromocytomas and neuroblastomas. 123 I-mIBG SPECT/CT imaging is performed for staging, follow-up and selection of patients for treatment with 131 I mIBG. As an alternative to 123 I, 124 I-mIBG PET/CT may be used, potentially taking advantage of the superior PET image quality. The purpose of this study was to investigate whether 124 I PET/CT improves image quality as compared with 123 I SPECT/CT for equal patient effective radiation dose (in mSv). METHODS Phantom measurements were performed using the NEMA-2007 image quality phantom. SPECT and PET reconstruction settings were used with and without time-of-flight (TOF) and point-spread-function (PSF) modeling. As a measure of image quality, the contrast-to-noise ratio (CNR) was calculated. The ratio of the 123 I to 124 I activity concentration was determined at which the contrast-to-noise ratio was equal for both modalities. This metric was defined as the contrast equivalent activity ratio (CEAR). RESULTS CEARs of 47.7, 25.6, 23.1, 14.6, 10.0, and 9.1 were obtained for a TOF and PSF modeled 124 I reconstruction method and an attenuation and scatter-corrected 123 I reconstruction method for sphere sizes of 10 to 37 mm, respectively. As the effective radiation dose of 124 I-mIBG is higher than of 123 I-mIBG (in mSv/MBq), an equal effective dose corresponds to a CEAR of 5 to 10. Therefore, CEARs higher than 5 to 10 indicate that 124 I PET/CT outperforms 123 I SPECT/CT in the sense of image quality for equal patient effective radiation dose. CONCLUSION The CEAR is much larger than a factor of 5 to 10 (needed for equal patient effective radiation dose) for most of the reconstruction methods and sphere sizes. Therefore, 124 I-mIBG PET/CT is expected to improve image quality and/or may be used to reduce effective patient dose as compared with 123 I-mIBG SPECT/CT.
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Affiliation(s)
- Casper Beijst
- Department of Radiology and Nuclear Medicine, UMC Utrecht, Utrecht, The Netherlands.,Image Sciences Institute, UMC Utrecht, Utrecht, The Netherlands
| | - Bart de Keizer
- Department of Radiology and Nuclear Medicine, UMC Utrecht, Utrecht, The Netherlands
| | - Marnix G E H Lam
- Department of Radiology and Nuclear Medicine, UMC Utrecht, Utrecht, The Netherlands
| | - Geert O Janssens
- Department of Radiation Oncology, UMC Utrecht, Utrecht, The Netherlands
| | | | - Hugo W A M de Jong
- Department of Radiology and Nuclear Medicine, UMC Utrecht, Utrecht, The Netherlands
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Suzuki A, Takeuchi W, Ueno Y, Kobashi K, Toyonaga T, Shiga T, Tamaki N. Monte Carlo-based scatter correction considering the tailing effect of a CdTe detector for dual-isotope brain SPECT imaging. Biomed Phys Eng Express 2016. [DOI: 10.1088/2057-1976/2/4/045010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Simultaneous Tc-99m and I-123 dual-radionuclide imaging with a solid-state detector-based brain-SPECT system and energy-based scatter correction. EJNMMI Phys 2016; 3:10. [PMID: 27357946 PMCID: PMC4927533 DOI: 10.1186/s40658-016-0147-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 06/09/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A brain single-photon emission computed tomography (SPECT) system using cadmium telluride (CdTe) solid-state detectors was previously developed. This CdTe-SPECT system is suitable for simultaneous dual-radionuclide imaging due to its fine energy resolution (6.6 %). However, the problems of down-scatter and low-energy tail due to the spectral characteristics of a pixelated solid-state detector should be addressed. The objective of this work was to develop a system for simultaneous Tc-99m and I-123 brain studies and evaluate its accuracy. METHODS A scatter correction method using five energy windows (FiveEWs) was developed. The windows are Tc-lower, Tc-main, shared sub-window of Tc-upper and I-lower, I-main, and I-upper. This FiveEW method uses pre-measured responses for primary gamma rays from each radionuclide to compensate for the overestimation of scatter by the triple-energy window method that is used. Two phantom experiments and a healthy volunteer experiment were conducted using the CdTe-SPECT system. A cylindrical phantom and a six-compartment phantom with five different mixtures of Tc-99m and I-123 and a cold one were scanned. The quantitative accuracy was evaluated using 18 regions of interest for each phantom. In the volunteer study, five healthy volunteers were injected with Tc-99m human serum albumin diethylene triamine pentaacetic acid (HSA-D) and scanned (single acquisition). They were then injected with I-123 N-isopropyl-4-iodoamphetamine hydrochloride (IMP) and scanned again (dual acquisition). The counts of the Tc-99m images for the single and dual acquisitions were compared. RESULTS In the cylindrical phantom experiments, the percentage difference (PD) between the single and dual acquisitions was 5.7 ± 4.0 % (mean ± standard deviation). In the six-compartment phantom experiment, the PDs between measured and injected activity for Tc-99m and I-123 were 14.4 ± 11.0 and 2.3 ± 1.8 %, respectively. In the volunteer study, the PD between the single and dual acquisitions was 4.5 ± 3.4 %. CONCLUSIONS This CdTe-SPECT system using the FiveEW method can provide accurate simultaneous dual-radionuclide imaging. A solid-state detector SPECT system using the FiveEW method will permit quantitative simultaneous Tc-99m and I-123 study to become clinically applicable.
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Jha AK, Caffo B, Frey EC. A no-gold-standard technique for objective assessment of quantitative nuclear-medicine imaging methods. Phys Med Biol 2016; 61:2780-800. [PMID: 26982626 DOI: 10.1088/0031-9155/61/7/2780] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The objective optimization and evaluation of nuclear-medicine quantitative imaging methods using patient data is highly desirable but often hindered by the lack of a gold standard. Previously, a regression-without-truth (RWT) approach has been proposed for evaluating quantitative imaging methods in the absence of a gold standard, but this approach implicitly assumes that bounds on the distribution of true values are known. Several quantitative imaging methods in nuclear-medicine imaging measure parameters where these bounds are not known, such as the activity concentration in an organ or the volume of a tumor. We extended upon the RWT approach to develop a no-gold-standard (NGS) technique for objectively evaluating such quantitative nuclear-medicine imaging methods with patient data in the absence of any ground truth. Using the parameters estimated with the NGS technique, a figure of merit, the noise-to-slope ratio (NSR), can be computed, which can rank the methods on the basis of precision. An issue with NGS evaluation techniques is the requirement of a large number of patient studies. To reduce this requirement, the proposed method explored the use of multiple quantitative measurements from the same patient, such as the activity concentration values from different organs in the same patient. The proposed technique was evaluated using rigorous numerical experiments and using data from realistic simulation studies. The numerical experiments demonstrated that the NSR was estimated accurately using the proposed NGS technique when the bounds on the distribution of true values were not precisely known, thus serving as a very reliable metric for ranking the methods on the basis of precision. In the realistic simulation study, the NGS technique was used to rank reconstruction methods for quantitative single-photon emission computed tomography (SPECT) based on their performance on the task of estimating the mean activity concentration within a known volume of interest. Results showed that the proposed technique provided accurate ranking of the reconstruction methods for 97.5% of the 50 noise realizations. Further, the technique was robust to the choice of evaluated reconstruction methods. The simulation study pointed to possible violations of the assumptions made in the NGS technique under clinical scenarios. However, numerical experiments indicated that the NGS technique was robust in ranking methods even when there was some degree of such violation.
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Affiliation(s)
- Abhinav K Jha
- Division of Medical Imaging Physics, Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
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Kobayashi M, Matsunari I, Nishi K, Mizutani A, Miyazaki Y, Ogai K, Sugama J, Shiba K, Kawai K, Kinuya S. Simultaneous acquisition of (99m)Tc- and (123)I-labeled radiotracers using a preclinical SPECT scanner with CZT detectors. Ann Nucl Med 2016; 30:263-71. [PMID: 26747655 DOI: 10.1007/s12149-015-1055-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 12/23/2015] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Simultaneous acquisition of (99m)Tc and (123)I was evaluated using a preclinical SPECT scanner with cadmium zinc telluride (CZT)-based detectors. METHODS 10-ml cylindrical syringes contained about 37 MBq (99m)Tc-tetrofosmin ((99m)Tc-TF) or 37 MBq (123)I-15-(p-iodophenyl)-3R,S-methyl pentadecanoic acid ((123)I-BMIPP) were used to assess the relationship between these SPECT radioactive counts and radioactivity. Two 10-ml syringes contained 100 or 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP to assess the influence of (99m)Tc upscatter and (123)I downscatter, respectively. A rat-sized cylindrical phantom also contained both 100 or 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP. The two 10-ml syringes and phantom were scanned using a pinhole collimator for rats. Myocardial infarction model rats were examined using 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP. Two 1-ml syringes contained 105 MBq (99m)Tc-labeled hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) and 35 MBq (123)I-labeled N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) nortropane ((123)I-FP-CIT). The two 1-ml syringes were scanned using a pinhole collimator for mice. Normal mice were examined using 105 MBq (99m)Tc-HMPAO and 35 MBq (123)I-FP-CIT. RESULTS The relationship between SPECT radioactive counts and radioactivity was excellent. Downscatter contamination of (123)I-BMIPP exhibited fewer radioactive counts for 300 MBq (99m)Tc-TF without scatter correction (SC) in 125-150 keV. There was no upscatter contamination of (99m)Tc-TF in 150-175 keV. In the rat-sized phantom, the radioactive count ratio decreased to 4.0 % for 300 MBq (99m)Tc-TF without SC in 125-150 keV. In the rats, myocardial images and radioactive counts of (99m)Tc-TF with the dual tracer were identical to those of the (99m)Tc-TF single injection. Downscatter contamination of (123)I-FP-CIT was 4.2 % without SC in 125-150 keV. In the first injection of (99m)Tc-HMPAO and second injection of (123)I-FP-CIT, brain images and radioactive counts of (99m)Tc-HMPAO with the dual tracer in normal mice also were the similar to those of the (99m)Tc-HMPAO single injection. In the first injection of (123)I-FP-CIT and second injection of (99m)Tc-HMPAO, the brain images and radioactive counts with the dual tracer were not much different from those of the (123)I-FP-CIT single injection. CONCLUSIONS Dual-tracer imaging of (99m)Tc- and (123)I-labeled radiotracers is feasible in a preclinical SPECT scanner with CZT detector. When higher radioactivity of (99m)Tc-labeled radiotracers relative to (123)I-labeled radiotracers is applied, correction methods are not necessarily required for the quantification of (99m)Tc- and (123)I-labeled radiotracers when using a preclinical SPECT scanner with CZT detector.
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Affiliation(s)
- Masato Kobayashi
- Wellness Promotion Science Center, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 920-0942, Japan.
| | - Ichiro Matsunari
- Clinical Research Department, The Medical and Pharmacological Research Center Foundation, Hakui, Japan
- Division of Nuclear Medicine, Department of Radiology, Saitama Medical University Hospital, Saitama, Japan
| | - Kodai Nishi
- Department of Radioisotope Medicine, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan
| | - Asuka Mizutani
- Graduate School of Medicine, Division of Health Sciences, Osaka University, Osaka, Japan
| | - Yoshiharu Miyazaki
- Clinical Research Department, The Medical and Pharmacological Research Center Foundation, Hakui, Japan
| | - Kazuhiro Ogai
- Wellness Promotion Science Center, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 920-0942, Japan
| | - Jyunko Sugama
- Wellness Promotion Science Center, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 920-0942, Japan
| | - Kazuhiro Shiba
- Division of Tracer Kinetics, Advanced Science Research Center, Kanazawa University, Kanazawa, Japan
| | - Keiichi Kawai
- School of Health Sciences, College of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Seigo Kinuya
- School of Medical Sciences, College of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
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Hiruy H, Fuchs EJ, Marzinke MA, Bakshi RP, Breakey JC, Aung WS, Manohar M, Yue C, Caffo BS, Du Y, Abebe KZ, Spiegel HM, Rohan LC, McGowan I, Hendrix CW. A Phase 1 Randomized, Blinded Comparison of the Pharmacokinetics and Colonic Distribution of Three Candidate Rectal Microbicide Formulations of Tenofovir 1% Gel with Simulated Unprotected Sex (CHARM-02). AIDS Res Hum Retroviruses 2015; 31:1098-108. [PMID: 26227279 DOI: 10.1089/aid.2015.0098] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
CHARM-02 is a crossover, double-blind, randomized trial to compare the safety and pharmacokinetics of three rectally applied tenofovir 1% gel candidate rectal microbicides of varying osmolalities: vaginal formulation (VF) (3111 mOsmol/kg), the reduced glycerin vaginal formulation (RGVF) (836 mOsmol/kg), and an isoosmolal rectal-specific formulation (RF) (479 mOsmol/kg). Participants (n = 9) received a single, 4 ml, radiolabeled dose of each gel twice, once with and once without simulated unprotected receptive anal intercourse (RAI). The safety, plasma tenofovir pharmacokinetics, colonic small molecule permeability, and SPECT/CT imaging of lower gastrointestinal distribution of drug and virus surrogate were assessed. There were no Grade 3 or 4 adverse events reported for any of the products. Overall, there were more Grade 2 adverse events in the VF group compared to RF (p = 0.006) and RGVF (p = 0.048). In the absence of simulated unprotected RAI, VF had up to 3.8-fold greater systemic tenofovir exposure, 26- to 234-fold higher colonic permeability of the drug surrogate, and 1.5- to 2-fold greater proximal migration in the colonic lumen, when compared to RF and RGVF. Similar trends were observed with simulated unprotected RAI, but most did not reach statistical significance. SPECT analysis showed 86% (standard deviation 19%) of the drug surrogate colocalized with the virus surrogate in the colonic lumen. There were no significant differences between the RGVF and RF formulation, with the exception of a higher plasma tenofovir concentration of RGVF in the absence of simulated unprotected RAI. VF had the most adverse events, highest plasma tenofovir concentrations, greater mucosal permeability of the drug surrogate, and most proximal colonic luminal migration compared to RF and RGVF formulations. There were no major differences between RF and RGVF formulations. Simultaneous assessment of toxicity, systemic and luminal pharmacokinetics, and colocalization of drug and viral surrogates substantially informs rectal microbicide product development.
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Affiliation(s)
- Hiwot Hiruy
- Department of Medicine (Clinical Pharmacology), Johns Hopkins University, Baltimore, Maryland
| | - Edward J. Fuchs
- Department of Medicine (Clinical Pharmacology), Johns Hopkins University, Baltimore, Maryland
| | - Mark A. Marzinke
- Department of Medicine (Clinical Pharmacology), Johns Hopkins University, Baltimore, Maryland
| | - Rahul P. Bakshi
- Department of Medicine (Clinical Pharmacology), Johns Hopkins University, Baltimore, Maryland
| | - Jennifer C. Breakey
- Department of Medicine (Clinical Pharmacology), Johns Hopkins University, Baltimore, Maryland
| | - Wutyi S. Aung
- Department of Medicine (Clinical Pharmacology), Johns Hopkins University, Baltimore, Maryland
| | - Madhuri Manohar
- Department of Medicine (Clinical Pharmacology), Johns Hopkins University, Baltimore, Maryland
| | - Chen Yue
- Department of Biostatistics, Johns Hopkins School of Public Health, Baltimore, Maryland
| | - Brian S. Caffo
- Department of Biostatistics, Johns Hopkins School of Public Health, Baltimore, Maryland
| | - Yong Du
- Department of Radiology, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Kaleab Z. Abebe
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Hans M.L. Spiegel
- HJF-DAIDS, a Division of The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Contractor to National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland
| | - Lisa C. Rohan
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
- Magee-Womens Research Institute, Pittsburgh, Pennsylvania
| | - Ian McGowan
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
- Magee-Womens Research Institute, Pittsburgh, Pennsylvania
| | - Craig W. Hendrix
- Department of Medicine (Clinical Pharmacology), Johns Hopkins University, Baltimore, Maryland
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Leyva F, Fuchs EJ, Bakshi R, Carballo-Dieguez A, Ventuneac A, Yue C, Caffo B, Du Y, Torbenson M, Li L, Mullin G, Lee L, Rohan L, Anton PA, Hendrix CW. Simultaneous Evaluation of Safety, Acceptability, Pericoital Kinetics, and Ex Vivo Pharmacodynamics Comparing Four Rectal Microbicide Vehicle Candidates. AIDS Res Hum Retroviruses 2015; 31:1089-97. [PMID: 26066390 DOI: 10.1089/aid.2015.0086] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Preexposure prophylaxis (PrEP) of HIV infection with tenofovir-containing regimens is effective, but plagued by poor adherence in some studies. Options for safe, effective, and acceptable PrEP products, especially for men and women at risk of HIV via receptive anal intercourse (RAI), are needed. We performed a randomized, partially blinded, first-in-human evaluation of four candidate rectal microbicide vehicles-aqueous gel, aqueous fluid, lipid gel, and lipid fluid-to select a prototype for further clinical development. Eight seronegative participants received three doses of each product with each dose separated by at least 2 weeks: one dose was given alone without simulated RAI in clinic, another dose was followed by simulated RAI in clinic, and another dose was self-administered at home in the context of RAI with a partner. Assessments included safety, acceptability, colon histology, ex vivo HIV infectivity of colon tissue explants, and colonic luminal distribution of vehicle and HIV surrogates. Adverse events were all mild and mainly sigmoidoscopy associated. There were minor differences in colon distribution of products and little effect of RAI. Vehicle distribution covered 95% (±7% standard deviation) of the distribution of an HIV surrogate in the colonic lumen. The lipid fluid vehicle increased HIV colon tissue infectability 5-fold [log10 p24 0.68 (95% confidence interval 0.08, 1.28)] and aqueous gel provided 6-fold protection [log10 p24 0.80 (95% confidence interval 0.20, 1.41)] compared to no product baseline. Colon permeability of lipid vehicles was more than 10-fold greater than aqueous vehicles. All products received similar acceptability ratings, though trends favored the gel products. Intensive simultaneous assessment of safety and toxicity, luminal and tissue distribution, ex vivo HIV infectivity, and product acceptability in relevant sexual contexts provided clear differentiation among candidate gels very early in product development. We selected the aqueous gel for further development as a rectal microbicide vehicle.
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Affiliation(s)
- Francisco Leyva
- Department of Medicine (Clinical Pharmacology), The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Edward J. Fuchs
- Department of Medicine (Clinical Pharmacology), The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Rahul Bakshi
- Department of Medicine (Clinical Pharmacology), The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Alex Carballo-Dieguez
- Department of Medicine (Gastroenterology), The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ana Ventuneac
- Department of Medicine (Gastroenterology), The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Chen Yue
- Department of Biostatistics, The Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland
| | - Brian Caffo
- Department of Biostatistics, The Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland
| | - Yong Du
- Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | | | - Liye Li
- Department of Medicine (Clinical Pharmacology), The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Gerald Mullin
- HIV Center for Clinical and Behavioral Studies, Columbia University, New York, New York
| | - Linda Lee
- HIV Center for Clinical and Behavioral Studies, Columbia University, New York, New York
| | - Lisa Rohan
- Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Peter A. Anton
- UCLA Center for HIV Prevention Research, UCLA AIDS Institute, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Craig W. Hendrix
- Department of Medicine (Clinical Pharmacology), The Johns Hopkins University School of Medicine, Baltimore, Maryland
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Abou DS, Pickett JE, Thorek DLJ. Nuclear molecular imaging with nanoparticles: radiochemistry, applications and translation. Br J Radiol 2015; 88:20150185. [PMID: 26133075 PMCID: PMC4730968 DOI: 10.1259/bjr.20150185] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Molecular imaging provides considerable insight into biological processes for greater understanding of health and disease. Numerous advances in medical physics, chemistry and biology have driven the growth of this field in the past two decades. With exquisite sensitivity, depth of detection and potential for theranostics, radioactive imaging approaches have played a major role in the emergence of molecular imaging. At the same time, developments in materials science, characterization and synthesis have led to explosive progress in the nanoparticle (NP) sciences. NPs are generally defined as particles with a diameter in the nanometre size range. Unique physical, chemical and biological properties arise at this scale, stimulating interest for applications as diverse as energy production and storage, chemical catalysis and electronics. In biomedicine, NPs have generated perhaps the greatest attention. These materials directly interface with life at the subcellular scale of nucleic acids, membranes and proteins. In this review, we will detail the advances made in combining radioactive imaging and NPs. First, we provide an overview of the NP platforms and their properties. This is followed by a look at methods for radiolabelling NPs with gamma-emitting radionuclides for use in single photon emission CT and planar scintigraphy. Next, utilization of positron-emitting radionuclides for positron emission tomography is considered. Finally, recent advances for multimodal nuclear imaging with NPs and efforts for clinical translation and ongoing trials are discussed.
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Affiliation(s)
- D S Abou
- 1 Division of Nuclear Medicine, Russell H. Morgan Department of Radiology and Radiological Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - J E Pickett
- 1 Division of Nuclear Medicine, Russell H. Morgan Department of Radiology and Radiological Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - D L J Thorek
- 1 Division of Nuclear Medicine, Russell H. Morgan Department of Radiology and Radiological Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.,2 Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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15
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Elschot M, Smits MLJ, Nijsen JFW, Lam MGEH, Zonnenberg BA, van den Bosch MAAJ, Viergever MA, de Jong HWAM. Quantitative Monte Carlo-based holmium-166 SPECT reconstruction. Med Phys 2014; 40:112502. [PMID: 24320461 DOI: 10.1118/1.4823788] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Quantitative imaging of the radionuclide distribution is of increasing interest for microsphere radioembolization (RE) of liver malignancies, to aid treatment planning and dosimetry. For this purpose, holmium-166 ((166)Ho) microspheres have been developed, which can be visualized with a gamma camera. The objective of this work is to develop and evaluate a new reconstruction method for quantitative (166)Ho SPECT, including Monte Carlo-based modeling of photon contributions from the full energy spectrum. METHODS A fast Monte Carlo (MC) simulator was developed for simulation of (166)Ho projection images and incorporated in a statistical reconstruction algorithm (SPECT-fMC). Photon scatter and attenuation for all photons sampled from the full (166)Ho energy spectrum were modeled during reconstruction by Monte Carlo simulations. The energy- and distance-dependent collimator-detector response was modeled using precalculated convolution kernels. Phantom experiments were performed to quantitatively evaluate image contrast, image noise, count errors, and activity recovery coefficients (ARCs) of SPECT-fMC in comparison with those of an energy window-based method for correction of down-scattered high-energy photons (SPECT-DSW) and a previously presented hybrid method that combines MC simulation of photopeak scatter with energy window-based estimation of down-scattered high-energy contributions (SPECT-ppMC+DSW). Additionally, the impact of SPECT-fMC on whole-body recovered activities (A(est)) and estimated radiation absorbed doses was evaluated using clinical SPECT data of six (166)Ho RE patients. RESULTS At the same noise level, SPECT-fMC images showed substantially higher contrast than SPECT-DSW and SPECT-ppMC+DSW in spheres ≥ 17 mm in diameter. The count error was reduced from 29% (SPECT-DSW) and 25% (SPECT-ppMC+DSW) to 12% (SPECT-fMC). ARCs in five spherical volumes of 1.96-106.21 ml were improved from 32%-63% (SPECT-DSW) and 50%-80% (SPECT-ppMC+DSW) to 76%-103% (SPECT-fMC). Furthermore, SPECT-fMC recovered whole-body activities were most accurate (A(est) = 1.06 × A - 5.90 MBq, R(2) = 0.97) and SPECT-fMC tumor absorbed doses were significantly higher than with SPECT-DSW (p = 0.031) and SPECT-ppMC+DSW (p = 0.031). CONCLUSIONS The quantitative accuracy of (166)Ho SPECT is improved by Monte Carlo-based modeling of the image degrading factors. Consequently, the proposed reconstruction method enables accurate estimation of the radiation absorbed dose in clinical practice.
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Affiliation(s)
- Mattijs Elschot
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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16
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Du Y, Bhattacharya M, Frey EC. Simultaneous Tc-99m/I-123 dual-radionuclide myocardial perfusion/innervation imaging using Siemens IQ-SPECT with SMARTZOOM collimator. Phys Med Biol 2014; 59:2813-28. [PMID: 24819280 PMCID: PMC4142679 DOI: 10.1088/0031-9155/59/11/2813] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Simultaneous dual-radionuclide myocardial perfusion/innervation SPECT imaging can provide important information about the mismatch between scar tissue and denervated regions. The Siemens IQ-SPECT system developed for cardiac imaging uses a multifocal SMARTZOOM collimator to achieve a four-fold sensitivity for the cardiac region, compared to a typical parallel-hole low-energy high-resolution collimator, but without the data truncation that can result with conventional converging-beam collimators. The increased sensitivity allows shorter image acquisition times or reduced patient dose, making IQ-SPECT ideal for simultaneous dual-radionuclide SPECT, where reduced administrated activity is desirable in order to reduce patient radiation exposure. However, crosstalk is a major factor affecting the image quality in dual-radionuclide imaging. In this work we developed a model-based method that can estimate and compensate for the crosstalk in IQ-SPECT data. The crosstalk model takes into account interactions in the object and collimator-detector system. Scatter in the object was modeled using the effective source scatter estimation technique (ESSE), previously developed to model scatter with parallel-hole collimators. The geometric collimator-detector response was analytically modeled in the IQ-SPECT projector. The estimated crosstalk was then compensated for in an iterative reconstruction process. The new method was validated with data from both Monte Carlo simulations and physical phantom experiments. The results showed that the estimated crosstalk was in good agreement with simulated and measured results. After model-based compensation the images from simultaneous dual-radionuclide acquisitions were similar in quality to those from single-radionuclide acquisitions that did not have crosstalk contamination. The proposed model-based method can be used to improve simultaneous dual-radionuclide images acquired using IQ-SPECT. This work also demonstrates that ESSE scatter modeling can be applied to non-parallel-beam projection geometries.
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Affiliation(s)
- Yong Du
- Department of Radiology, Johns Hopkins University, 601 N Caroline Street, JOHC 4263, Baltimore, MD 21287, USA
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17
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Munley MT, Kagadis GC, McGee KP, Kirov AS, Jang S, Mutic S, Jeraj R, Xing L, Bourland JD. An introduction to molecular imaging in radiation oncology: a report by the AAPM Working Group on Molecular Imaging in Radiation Oncology (WGMIR). Med Phys 2014; 40:101501. [PMID: 24089890 DOI: 10.1118/1.4819818] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Molecular imaging is the direct or indirect noninvasive monitoring and recording of the spatial and temporal distribution of in vivo molecular, genetic, and/or cellular processes for biochemical, biological, diagnostic, or therapeutic applications. Molecular images that indicate the presence of malignancy can be acquired using optical, ultrasonic, radiologic, radionuclide, and magnetic resonance techniques. For the radiation oncology physicist in particular, these methods and their roles in molecular imaging of oncologic processes are reviewed with respect to their physical bases and imaging characteristics, including signal intensity, spatial scale, and spatial resolution. Relevant molecular terminology is defined as an educational assist. Current and future clinical applications in oncologic diagnosis and treatment are discussed. National initiatives for the development of basic science and clinical molecular imaging techniques and expertise are reviewed, illustrating research opportunities in as well as the importance of this growing field.
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Affiliation(s)
- Michael T Munley
- Department of Radiation Oncology, Wake Forest School of Medicine, Winston-Salem, North Carolina 27157
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18
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Aguiar P, Pino F, Silva-Rodríguez J, Pavía J, Ros D, Ruibal Á, El Bitar Z. Analytical, experimental, and Monte Carlo system response matrix for pinhole SPECT reconstruction. Med Phys 2014; 41:032501. [DOI: 10.1118/1.4866380] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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19
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Suzuki Y, Yamaguchi M, Odaka H, Shimada H, Yoshida Y, Torikai K, Satoh T, Arakawa K, Kawachi N, Watanabe S, Takeda S, Ishikawa SN, Aono H, Watanabe S, Takahashi T, Nakano T. Three-dimensional and Multienergy Gamma-ray Simultaneous Imaging by Using a Si/CdTe Compton Camera. Radiology 2013; 267:941-7. [DOI: 10.1148/radiol.13121194] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Hijnen NM, de Vries A, Nicolay K, Grüll H. Dual-isotope 111In/177Lu SPECT imaging as a tool in molecular imaging tracer design. CONTRAST MEDIA & MOLECULAR IMAGING 2012; 7:214-22. [PMID: 22434634 DOI: 10.1002/cmmi.485] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The synthesis, design and subsequent pre-clinical testing of new molecular imaging tracers are topic of extensive research in healthcare. Quantitative dual-isotope SPECT imaging is proposed here as a tool in the design and validation of such tracers, as it can be used to quantify and compare the biodistribution of a specific ligand and its nonspecific control ligand, labeled with two different radionuclides, in the same animal. Since the biodistribution results are not blurred by experimental or physiological inter-animal variations, this approach allows determination of the ligand's net targeting effect. However, dual-isotope quantification is complicated by crosstalk between the two radionuclides used and the radionuclides should not influence the biodistribution of the tracer. Here, we developed a quantitative dual-isotope SPECT protocol using combined (111)Indium and (177)Lutetium and tested this tool for a well-known angiogenesis-specific ligand (cRGD peptide) in comparison to a potential nonspecific control (cRAD peptide). Dual-isotope SPECT imaging of the peptides showed a similar organ and tumor uptake to single-isotope studies (cRGDfK-DOTA, 1.5 ± 0.8%ID cm(-3); cRADfK-DOTA, 0.2 ± 0.1%ID cm(-3)), but with higher statistical relevance (p-value 0.007, n = 8). This demonstrated that, for the same relevance, seven animals were required in case of a single-isotope test design as compared with only three animals when a dual-isotope test was used. Interchanging radionuclides did not influence the biodistribution of the peptides. Dual-isotope SPECT after simultaneous injection of (111)In and (177)Lu-labeled cRGD and cRAD was shown to be a valuable method for paired testing of the in vivo target specificity of ligands in molecular imaging tracer design.
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Affiliation(s)
- Nicole M Hijnen
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, The Netherlands
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21
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Shcherbinin S, Chamoiseau S, Celler A. Quantitative image reconstruction for dual-isotope parathyroid SPECT/CT: phantom experiments and sample patient studies. Phys Med Biol 2012; 57:4755-69. [PMID: 22772024 DOI: 10.1088/0031-9155/57/15/4755] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We investigated the quantitative accuracy of the model-based dual-isotope single-photon emission computed tomography (DI-SPECT) reconstructions that use Klein-Nishina expressions to estimate the scattered photon contributions to the projection data. Our objective was to examine the ability of the method to recover the absolute activities pertaining to both radiotracers: Tc-99m and I-123. We validated our method through a series of phantom experiments performed using a clinical hybrid SPECT/CT camera (Infinia Hawkeye, GE Healthcare). Different activity ratios and different attenuating media were used in these experiments to create cross-talk effects of varying severity, which can occur in clinical studies. Accurate model-based corrections for scatter and cross-talk with CT attenuation maps allowed for the recovery of the absolute activities from DI-SPECT/CT scans with errors that ranged 0-10% for both radiotracers. The unfavorable activity ratios increased the computational burden but practically did not affect the resulting accuracy. The visual analysis of parathyroid patient data demonstrated that our model-based processing improved adenoma/background contrast and enhanced localization of small or faint adenomas.
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Affiliation(s)
- S Shcherbinin
- Department of Radiology, University of British Columbia, 366-828 West 10th Avenue, Vancouver BC, V5Z 1M9, Canada.
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22
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Hutton BF, Buvat I, Beekman FJ. Review and current status of SPECT scatter correction. Phys Med Biol 2011; 56:R85-112. [PMID: 21701055 DOI: 10.1088/0031-9155/56/14/r01] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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El Fakhri G, Ouyang J. Dual-radionuclide brain SPECT for the differential diagnosis of parkinsonism. Methods Mol Biol 2011; 680:237-246. [PMID: 21153385 DOI: 10.1007/978-1-60761-901-7_16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Parkinsonism is a neurological syndrome characterized by tremor, bradykinesia, rigidity, and postural instability. The underlying causes of parkinsonism are numerous. It is of paramount importance to make clean distinction among these diseases. However, the differential diagnosis of parkinsonism is challenging. Simultaneous dual-radionuclide brain SPECT allows us to assess both blood perfusion and dopamine transporter function under the identical physiological conditions. This approach has been proven to improve the differential diagnosis of parkinsonism. The simultaneous (99m)Tc-ECD/(123)I-FP-CIT brain SPECT protocols, which are used for the differential diagnosis of idiopathic Parkinson's disease and multiple system atrophy as well as corticobasal degeneration and progressive supranuclear palsy, are presented.
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Affiliation(s)
- Georges El Fakhri
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Boston, MA 02114, USA.
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Trott CM, Ouyang J, El Fakhri G. Comparison of simultaneous and sequential SPECT imaging for discrimination tasks in assessment of cardiac defects. Phys Med Biol 2010; 55:6897-910. [PMID: 21048290 DOI: 10.1088/0031-9155/55/22/019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Simultaneous rest perfusion/fatty-acid metabolism studies have the potential to replace sequential rest/stress perfusion studies for the assessment of cardiac function. Simultaneous acquisition has the benefits of increased signal and lack of need for patient stress, but is complicated by cross-talk between the two radionuclide signals. We consider a simultaneous rest (99m)Tc-sestamibi/(123)I-BMIPP imaging protocol in place of the commonly used sequential rest/stress (99m)Tc-sestamibi protocol. The theoretical precision with which the severity of a cardiac defect and the transmural extent of infarct can be measured is computed for simultaneous and sequential SPECT imaging, and their performance is compared for discriminating (1) degrees of defect severity and (2) sub-endocardial from transmural defects. We consider cardiac infarcts for which reduced perfusion and metabolism are observed. From an information perspective, simultaneous imaging is found to yield comparable or improved performance compared with sequential imaging for discriminating both severity of defect and transmural extent of infarct, for three defects of differing location and size.
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Affiliation(s)
- C M Trott
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St, Boston, MA 02114, USA.
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