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Herraiz JL, Lopez-Montes A, Badal A. MCGPU-PET: An Open-Source Real-Time Monte Carlo PET Simulator. COMPUTER PHYSICS COMMUNICATIONS 2024; 296:109008. [PMID: 38145286 PMCID: PMC10735232 DOI: 10.1016/j.cpc.2023.109008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2023]
Abstract
Monte Carlo (MC) simulations are commonly used to model the emission, transmission, and/or detection of radiation in Positron Emission Tomography (PET). In this work, we introduce a new open-source MC software for PET simulation, MCGPU-PET, which has been designed to fully exploit the computing capabilities of modern GPUs to simulate the acquisition of more than 100 million coincidences per second from voxelized sources and material distributions. The new simulator is an extension of the PENELOPE-based MCGPU code previously used in cone-beam CT and mammography applications. We validated the accuracy of the accelerated code by comparing it to GATE and PeneloPET simulations achieving an agreement within 10 percent approximately. As an example application of the code for fast estimation of PET coincidences, a scan of the NEMA IQ phantom was simulated. A fully 3D sinogram with 6382 million true coincidences and 731 million scatter coincidences was generated in 54 seconds in one GPU. MCGPU-PET provides an estimation of true and scatter coincidences and spurious background (for positron-gamma emitters such as 124I) at a rate 3 orders of magnitude faster than CPU-based MC simulators. This significant speed-up enables the use of the code for accurate scatter and prompt-gamma background estimations within an iterative image reconstruction process.
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Affiliation(s)
- Joaquin L. Herraiz
- Complutense University of Madrid, EMFTEL, Grupo de Física Nuclear and IPARCOS, Madrid, 28040, Spain
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdiSSC), Madrid,28040, Spain
| | - Alejandro Lopez-Montes
- Complutense University of Madrid, EMFTEL, Grupo de Física Nuclear and IPARCOS, Madrid, 28040, Spain
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21205, United States of America
| | - Andreu Badal
- DIDSR, OSEL, CDRH, US Food and Drug Administration, Silver Spring, MD, 20993, USA
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Pratt EC, Lopez-Montes A, Volpe A, Crowley MJ, Carter LM, Mittal V, Pillarsetty N, Ponomarev V, Udías JM, Grimm J, Herraiz JL. Simultaneous quantitative imaging of two PET radiotracers via the detection of positron-electron annihilation and prompt gamma emissions. Nat Biomed Eng 2023; 7:1028-1039. [PMID: 37400715 PMCID: PMC10810307 DOI: 10.1038/s41551-023-01060-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 05/23/2023] [Indexed: 07/05/2023]
Abstract
In conventional positron emission tomography (PET), only one radiotracer can be imaged at a time, because all PET isotopes produce the same two 511 keV annihilation photons. Here we describe an image reconstruction method for the simultaneous in vivo imaging of two PET tracers and thereby the independent quantification of two molecular signals. This method of multiplexed PET imaging leverages the 350-700 keV range to maximize the capture of 511 keV annihilation photons and prompt γ-ray emission in the same energy window, hence eliminating the need for energy discrimination during reconstruction or for signal separation beforehand. We used multiplexed PET to track, in mice with subcutaneous tumours, the biodistributions of intravenously injected [124I]I-trametinib and 2-deoxy-2-[18F]fluoro-D-glucose, [124I]I-trametinib and its nanoparticle carrier [89Zr]Zr-ferumoxytol, and the prostate-specific membrane antigen (PSMA) and infused PSMA-targeted chimaeric antigen receptor T cells after the systemic administration of [68Ga]Ga-PSMA-11 and [124I]I. Multiplexed PET provides more information depth, gives new uses to prompt γ-ray-emitting isotopes, reduces radiation burden by omitting the need for an additional computed-tomography scan and can be implemented on preclinical and clinical systems without any modifications in hardware or image acquisition software.
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Affiliation(s)
- Edwin C Pratt
- Department of Pharmacology, Weill Cornell Graduate School, New York, NY, USA
- Molecular Pharmacology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Alejandro Lopez-Montes
- Nuclear Physics Group, EMFTEL and IPARCOS, Complutense University of Madrid, Madrid, Spain
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Alessia Volpe
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Michael J Crowley
- Department of Cell and Developmental Biology, Weill Cornell Graduate School, New York, NY, USA
| | - Lukas M Carter
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Vivek Mittal
- Department of Cell and Developmental Biology, Weill Cornell Graduate School, New York, NY, USA
- Department of Cardiothoracic Surgery, Weill Cornell Medicine, New York, USA
- Neuberger Berman Lung Cancer Center, Weill Cornell Medicine, New York, USA
- Sandra and Edward Meyer Cancer Center, Weill Cornell Medicine, New York, USA
| | | | - Vladimir Ponomarev
- Molecular Pharmacology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Jose M Udías
- Nuclear Physics Group, EMFTEL and IPARCOS, Complutense University of Madrid, Madrid, Spain
- Instituto de Investigación Sanitaria Hospital Clínico San Carlos, Madrid, Spain
| | - Jan Grimm
- Department of Pharmacology, Weill Cornell Graduate School, New York, NY, USA.
- Molecular Pharmacology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
| | - Joaquin L Herraiz
- Nuclear Physics Group, EMFTEL and IPARCOS, Complutense University of Madrid, Madrid, Spain.
- Instituto de Investigación Sanitaria Hospital Clínico San Carlos, Madrid, Spain.
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Fanchon LM, Beattie BJ, Pentlow K, Larson SM, Humm JL. Optimizing reconstruction parameters for quantitative 124I-PET in the presence of therapeutic doses of 131I. EJNMMI Phys 2021; 8:50. [PMID: 34250566 PMCID: PMC8273044 DOI: 10.1186/s40658-021-00398-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/23/2021] [Indexed: 11/11/2022] Open
Abstract
Background The goal of this work was to determine the quantitative accuracy and optimal reconstruction parameters for 124I-PET imaging in the presence of therapeutic levels of 131I. In this effort, images were acquired on a GE D710 PET/CT scanner using a NEMA IEC phantom with spheres containing 124I and increasing amounts of 131I activity in the background. At each activity level, two scans were acquired, one with the phantom centered in the field of view (FOV) and one 11.2 cm off-center. Reconstructions used an ordered subset expectation maximization algorithm with up to 100 iterations of 16 subsets, with and without time-of-flight (TOF) information. Results were evaluated visually and by comparing the 124I activity relative to the scan performed in the absence of 131I. Results 131I within the FOV added to the randoms rate, to dead time, and to pile-up within the detectors. Using our standard clinical reconstruction parameters, the image quality and quantitative accuracy suffered at 131I activities above 1.4 GBq. Convergence rates slowed progressively in the presence of increasing amounts of 131I for both TOF and nonTOF reconstructions. TOF reconstructions converged more quickly than nonTOF but often towards erroneous concentrations. Iterating nonTOF reconstructions to convergence produced quantitatively accurate images except for the off-center phantom at the very highest level of background 131I tested. Conclusions This study shows that quantitative PET is feasible in the presence of large amounts of 131I. The high randoms fractions resulted in slow reconstruction convergence and negatively impacted TOF corrections and/or the accuracy of TOF information. Therefore, increased iterations and nonTOF reconstructions are recommended. Supplementary Information The online version contains supplementary material available at 10.1186/s40658-021-00398-z.
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Affiliation(s)
- Louise M Fanchon
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA
| | - Bradley J Beattie
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA
| | - Keith Pentlow
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA
| | - Steven M Larson
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA
| | - John L Humm
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA.
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Abstract
Yttrium-86 is a non-standard positron emitter that can provide dosimetry information prior to therapy with yttrium-90 radiopharmaceuticals and be used to follow biochemical processes. In this chapter, we discuss the production, purification and applications of 86Y for PET imaging. More specifically, 86Y radiolabeling is highlighted and protocols to determine the radiochemical purity of 86Y-DOTA and 86Y-DTPA are presented.
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Affiliation(s)
- Mariane Le Fur
- The Athinoula A. Martinos Center for Biomedical Imaging, The Institute for Innovation in Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States.
| | - Peter Caravan
- The Athinoula A. Martinos Center for Biomedical Imaging, The Institute for Innovation in Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States
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Rosar F, Buchholz HG, Michels S, Hoffmann MA, Piel M, Waldmann CM, Rösch F, Reuss S, Schreckenberger M. Image quality analysis of 44Sc on two preclinical PET scanners: a comparison to 68Ga. EJNMMI Phys 2020; 7:16. [PMID: 32166581 PMCID: PMC7067939 DOI: 10.1186/s40658-020-0286-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 03/03/2020] [Indexed: 11/10/2022] Open
Abstract
Background 44Sc has been increasingly investigated as a potential alternative to 68Ga in the development of tracers for positron emission tomography (PET). The lower mean positron energy of 44Sc (0.63 MeV) compared to 68Ga (0.83 MeV) can result in better spatial image resolutions. However, high-energy γ-rays (1157 keV) are emitted at high rates (99.9%) during 44Sc decay, which can reduce image quality. Therefore, we investigated the impact of these physical properties and performed an unbiased performance evaluation of 44Sc and 68Ga with different imaging phantoms (image quality phantom, Derenzo phantom, and three-rod phantom) on two preclinical PET scanners (Mediso nanoScan PET/MRI, Siemens microPET Focus 120). Results Despite the presence of high-energy γ-rays in 44Sc decay, a higher image resolution of small structures was observed with 44Sc when compared to 68Ga. Structures as small as 1.3 mm using the Mediso system, and as small as 1.0 mm using the Siemens system, could be visualized and analyzed by calculating full width at half maximum. Full widths at half maxima were similar for both isotopes. For image quality comparison, we calculated recovery coefficients in 1–5 mm rods and spillover ratios in either air, water, or bone-equivalent material (Teflon). Recovery coefficients for 44Sc were significantly higher than those for 68Ga. Despite the lower positron energy, 44Sc-derived spillover ratio (SOR) values were similar or slightly higher to 68Ga-derived SOR values. This may be attributed to the higher background caused by the additional γ-rays. On the Siemens system, an overestimation of scatter correction in the central part of the phantom was observed causing a virtual disappearance of spillover inside the three-rod phantom. Conclusion Based on these findings, 44Sc appears to be a suitable alternative to 68Ga. The superior image resolution makes it an especially strong competitor in preclinical settings. The additional γ-emissions have a small impact on the imaging resolution but cause higher background noises and can effect an overestimation of scatter correction, depending on the PET system and phantom.
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Affiliation(s)
- Florian Rosar
- Department of Nuclear Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany. .,Department of Nuclear Medicine, Saarland University Medical Center, Homburg, Germany.
| | - Hans-Georg Buchholz
- Department of Nuclear Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Sebastian Michels
- Department of Nuclear Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Manuela A Hoffmann
- Department of Nuclear Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Markus Piel
- Institute of Nuclear Chemistry, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Christopher M Waldmann
- Department of Nuclear Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Frank Rösch
- Institute of Nuclear Chemistry, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Stefan Reuss
- Department of Nuclear Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Mathias Schreckenberger
- Department of Nuclear Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
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Sitarz M, Cussonneau JP, Matulewicz T, Haddad F. Radionuclide candidates for β+γ coincidence PET: An overview. Appl Radiat Isot 2020; 155:108898. [DOI: 10.1016/j.apradiso.2019.108898] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 09/11/2019] [Accepted: 09/19/2019] [Indexed: 12/20/2022]
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Lee YS, Kim HJ, Kim JS. Improved Quantification of 18F-FDG PET during 131I-Rituximab Therapy on Mouse Lymphoma Models after 131I Prompt Emission Correction. Diagnostics (Basel) 2019; 9:diagnostics9040144. [PMID: 31597334 PMCID: PMC6963650 DOI: 10.3390/diagnostics9040144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 10/07/2019] [Indexed: 11/25/2022] Open
Abstract
18F-FDG Positron Emission Tomography (PET) is used to monitor tumor response to 131I-therapy, but is confounded by prompt emissions (284, 364, 637, and 723 keV) from 131I, particularly in animal PET imaging. We propose a method for correcting this emission in 18F-FDG PET. The 131I prompt emission effect was assessed within various energy windows and various activities. We applied a single gamma correction method to a phantom and in vivo mouse model. The 131I prompt emission fraction was 12% when 300 µCi of 131I and 100 µCi of FDG were administered, and increased exponentially with escalating 131I activity for all energy windows. The difference in spill-over ratio was reduced to <5% after 131I prompt emission correction. In the mouse model, the standard uptake value (SUV) did not differ significantly between FDG PET only (gold standard) and FDG PET after 131I prompt emission-correction, whereas it was overestimated by 38% before correction. Contrast was improved by 18% after 131I prompt emission correction. We first found that count contamination on 18F-FDG follow-up scans due to 131I spilled-over count after 131I rituximab tumor targeted therapy. Our developed 131I prompt emission-correction method increased accuracy during measurement of standard uptake values on 18F-FDG PET.
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Affiliation(s)
- Young Sub Lee
- Division of RI Application, Korea Institute Radiological and Medical Sciences, Seoul 01812, Korea;
- Division of Radiation Regulation, Department of Medical Radiation Safety, Korea Institute of Nuclear Safety, Daejeon 34142, Korea
| | - Hee-Joung Kim
- Department of Radiation Convergence Engineering and Research Institute of Health Science, Yonsei University, Wonju 26493, Korea;
| | - Jin Su Kim
- Division of RI Application, Korea Institute Radiological and Medical Sciences, Seoul 01812, Korea;
- Radiological and Medico-Oncological Sciences, University of Science and Technology, Seoul 01812, Korea
- Correspondence: ; Tel.: +82-2-970-1661
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8
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Moncayo VM, Garcia EV. Prompt-gamma compensation in Rb-82 myocardial perfusion 3D PET/CT: Effect on clinical practice. J Nucl Cardiol 2018; 25:606-608. [PMID: 27659456 DOI: 10.1007/s12350-016-0672-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 08/26/2016] [Indexed: 12/23/2022]
Affiliation(s)
- Valeria M Moncayo
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia.
| | - Ernest V Garcia
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia
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9
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Beijst C, Kunnen B, Lam MGEH, de Jong HWAM. Technical Advances in Image Guidance of Radionuclide Therapy. J Nucl Med Technol 2017; 45:272-279. [PMID: 29042472 DOI: 10.2967/jnmt.117.190991] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 07/05/2017] [Indexed: 11/16/2022] Open
Abstract
Internal radiation therapy with radionuclides (i.e., radionuclide therapy) owes its success to the many advantages over other, more conventional, treatment options. One distinct advantage of radionuclide therapies is the potential to use (part of) the emitted radiation for imaging of the radionuclide distribution. The combination of diagnostic and therapeutic properties in a set of matched radiopharmaceuticals (sometimes combined in a single radiopharmaceutical) is often referred to as theranostics and allows accurate diagnostic imaging before therapy. The use of imaging benefits treatment planning, dosimetry, and assessment of treatment response. This paper focuses on a selection of advances in imaging technology relevant for image guidance of radionuclide therapy. This involves developments in nuclear imaging modalities, as well as other anatomic and functional imaging modalities. The quality and quantitative accuracy of images used for guidance of radionuclide therapy is continuously being improved, which in turn may improve the therapeutic outcome and efficiency of radionuclide therapies.
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Affiliation(s)
- Casper Beijst
- Department of Radiology and Nuclear Medicine, UMC Utrecht, Utrecht, The Netherlands; and .,Image Sciences Institute, UMC Utrecht, Utrecht, The Netherlands
| | - Britt Kunnen
- Department of Radiology and Nuclear Medicine, UMC Utrecht, Utrecht, The Netherlands; and.,Image Sciences Institute, UMC Utrecht, Utrecht, The Netherlands
| | - Marnix G E H Lam
- Department of Radiology and Nuclear Medicine, UMC Utrecht, Utrecht, The Netherlands; and
| | - Hugo W A M de Jong
- Department of Radiology and Nuclear Medicine, UMC Utrecht, Utrecht, The Netherlands; and
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Alidori S, Thorek DLJ, Beattie BJ, Ulmert D, Almeida BA, Monette S, Scheinberg DA, McDevitt MR. Carbon nanotubes exhibit fibrillar pharmacology in primates. PLoS One 2017; 12:e0183902. [PMID: 28846728 PMCID: PMC5573305 DOI: 10.1371/journal.pone.0183902] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/14/2017] [Indexed: 01/15/2023] Open
Abstract
Nanomedicine rests at the nexus of medicine, bioengineering, and biology with great potential for improving health through innovation and development of new drugs and devices. Carbon nanotubes are an example of a fibrillar nanomaterial poised to translate into medical practice. The leading candidate material in this class is ammonium-functionalized carbon nanotubes (fCNT) that exhibits unexpected pharmacological behavior in vivo with important biotechnology applications. Here, we provide a multi-organ evaluation of the distribution, uptake and processing of fCNT in nonhuman primates using quantitative whole body positron emission tomography (PET), compartmental modeling of pharmacokinetic data, serum biomarkers and ex vivo pathology investigation. Kidney and liver are the two major organ systems that accumulate and excrete [86Y]fCNT in nonhuman primates and accumulation is cell specific as described by compartmental modeling analyses of the quantitative PET data. A serial two-compartment model explains renal processing of tracer-labeled fCNT; hepatic data fits a parallel two-compartment model. These modeling data also reveal significant elimination of the injected activity (>99.8%) from the primate within 3 days (t1/2 = 11.9 hours). These favorable results in nonhuman primates provide important insight to the fate of fCNT in vivo and pave the way to further engineering design considerations for sophisticated nanomedicines to aid late stage development and clinical use in man.
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Affiliation(s)
- Simone Alidori
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Daniel L. J. Thorek
- Departments of Radiology and Radiological Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Bradley J. Beattie
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - David Ulmert
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Bryan Aristega Almeida
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Sebastien Monette
- Tri-Instituitional Laboratory of Comparative Pathology, Memorial Sloan Kettering Cancer Center, The Rockefeller University, Weill Cornell Medicine, New York, New York, United States of America
| | - David A. Scheinberg
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
- Department of Pharmacology, Weill Cornell Medicine, New York, New York, United States of America
- Department of Medicine, Weill Cornell Medicine, New York, New York, United States of America
| | - Michael R. McDevitt
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
- Department of Radiology, Weill Cornell Medicine, New York, New York, United States of America
- * E-mail:
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Heußer T, Mann P, Rank CM, Schäfer M, Dimitrakopoulou-Strauss A, Schlemmer HP, Hadaschik BA, Kopka K, Bachert P, Kachelrieß M, Freitag MT. Investigation of the halo-artifact in 68Ga-PSMA-11-PET/MRI. PLoS One 2017; 12:e0183329. [PMID: 28817656 PMCID: PMC5560715 DOI: 10.1371/journal.pone.0183329] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 08/02/2017] [Indexed: 01/12/2023] Open
Abstract
Objectives Combined positron emission tomography (PET) and magnetic resonance imaging (MRI) targeting the prostate-specific membrane antigen (PSMA) with a 68Ga-labelled PSMA-analog (68Ga-PSMA-11) is discussed as a promising diagnostic method for patients with suspicion or history of prostate cancer. One potential drawback of this method are severe photopenic (halo-) artifacts surrounding the bladder and the kidneys in the scatter-corrected PET images, which have been reported to occur frequently in clinical practice. The goal of this work was to investigate the occurrence and impact of these artifacts and, secondly, to evaluate variants of the standard scatter correction method with regard to halo-artifact suppression. Methods Experiments using a dedicated pelvis phantom were conducted to investigate whether the halo-artifact is modality-, tracer-, and/or concentration-dependent. Furthermore, 31 patients with history of prostate cancer were selected from an ongoing 68Ga-PSMA-11-PET/MRI study. For each patient, PET raw data were reconstructed employing six different variants of PET scatter correction: absolute scatter scaling, relative scatter scaling, and relative scatter scaling combined with prompt gamma correction, each of which was combined with a maximum scatter fraction (MaxSF) of MaxSF = 75% or MaxSF = 40%. Evaluation of the reconstructed images with regard to halo-artifact suppression was performed both quantitatively using statistical analysis and qualitatively by two independent readers. Results The phantom experiments did not reveal any modality-dependency (PET/MRI vs. PET/CT) or tracer-dependency (68Ga vs. 18F-FDG). Patient- and phantom-based data indicated that halo-artifacts derive from high organ-to-background activity ratios (OBR) between bladder/kidneys and surrounding soft tissue, with a positive correlation between OBR and halo size. Comparing different variants of scatter correction, reducing the maximum scatter fraction from the default value MaxSF = 75% to MaxSF = 40% was found to efficiently suppress halo-artifacts in both phantom and patient data. In 1 of 31 patients, reducing the maximum scatter fraction provided new PET-based information changing the patient’s diagnosis. Conclusion Halo-artifacts are particularly observed for 68Ga-PSMA-11-PET/MRI due to 1) the biodistribution of the PSMA-11-tracer resulting in large OBRs for bladder and kidneys and 2) inaccurate scatter correction methods currently used in clinical routine, which tend to overestimate the scatter contribution. If not compensated for, 68Ga-PSMA-11 uptake pathologies may be masked by halo-artifacts leading to false-negative diagnoses. Reducing the maximum scatter fraction was found to efficiently suppress halo-artifacts.
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Affiliation(s)
- Thorsten Heußer
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Philipp Mann
- Applied Medical Radiation Physics, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Christopher M. Rank
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Martin Schäfer
- Divison of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | | | | | | | - Klaus Kopka
- Divison of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Peter Bachert
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Marc Kachelrieß
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Martin T. Freitag
- Department of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- * E-mail:
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12
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Rösch F, Herzog H, Qaim SM. The Beginning and Development of the Theranostic Approach in Nuclear Medicine, as Exemplified by the Radionuclide Pair 86Y and 90Y. Pharmaceuticals (Basel) 2017; 10:E56. [PMID: 28632200 PMCID: PMC5490413 DOI: 10.3390/ph10020056] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 06/13/2017] [Accepted: 06/15/2017] [Indexed: 11/29/2022] Open
Abstract
In the context of radiopharmacy and molecular imaging, the concept of theranostics entails a therapy-accompanying diagnosis with the aim of a patient-specific treatment. Using the adequate diagnostic radiopharmaceutical, the disease and the state of the disease are verified for an individual patient. The other way around, it verifies that the radiopharmaceutical in hand represents a target-specific and selective molecule: the "best one" for that individual patient. Transforming diagnostic imaging into quantitative dosimetric information, the optimum radioactivity (expressed in maximum radiation dose to the target tissue and tolerable dose to healthy organs) of the adequate radiotherapeutical is applied to that individual patient. This theranostic approach in nuclear medicine is traced back to the first use of the radionuclide pair 86Y/90Y, which allowed a combination of PET and internal radiotherapy. Whereas the β-emitting therapeutic radionuclide 90Y (t½ = 2.7 d) had been available for a long time via the 90Sr/90Y generator system, the β⁺ emitter 86Y (t½ = 14.7 h) had to be developed for medical application. A brief outline of the various aspects of radiochemical and nuclear development work (nuclear data, cyclotron irradiation, chemical processing, quality control, etc.) is given. In parallel, the paper discusses the methodology introduced to quantify molecular imaging of 86Y-labelled compounds in terms of multiple and long-term PET recordings. It highlights the ultimate goal of radiotheranostics, namely to extract the radiation dose of the analogue 90Y-labelled compound in terms of mGy or mSv per MBq 90Y injected. Finally, the current and possible future development of theranostic approaches based on different PET and therapy nuclides is discussed.
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Affiliation(s)
- Frank Rösch
- Institute of Nuclear Chemistry, Johannes Gutenberg University Mainz, Mainz D-55126, Germany.
| | - Hans Herzog
- Institute of Neuroscience and Medicine (INM), INM-4 (Physics of Medical Imaging), Research Center Jülich, Jülich D-52425, Germany.
| | - Syed M Qaim
- Institute of Neuroscience and Medicine (INM), INM-5 (nuclear Chemistry), Research Center Jülich, Jülich D-52425, Germany.
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Alidori S, Akhavein N, Thorek DLJ, Behling K, Romin Y, Queen D, Beattie BJ, Manova-Todorova K, Bergkvist M, Scheinberg DA, McDevitt MR. Targeted fibrillar nanocarbon RNAi treatment of acute kidney injury. Sci Transl Med 2016; 8:331ra39. [PMID: 27009268 DOI: 10.1126/scitranslmed.aac9647] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 02/29/2016] [Indexed: 12/11/2022]
Abstract
RNA interference has tremendous yet unrealized potential to treat a wide range of illnesses. Innovative solutions are needed to protect and selectively deliver small interfering RNA (siRNA) cargo to and within a target cell to fully exploit siRNA as a therapeutic tool in vivo. Herein, we describe ammonium-functionalized carbon nanotube (fCNT)-mediated transport of siRNA selectively and with high efficiency to renal proximal tubule cells in animal models of acute kidney injury (AKI). fCNT enhanced siRNA delivery to tubule cells compared to siRNA alone and effectively knocked down the expression of several target genes, includingTrp53,Mep1b,Ctr1, andEGFP A clinically relevant cisplatin-induced murine model of AKI was used to evaluate the therapeutic potential of fCNT-targeted siRNA to effectively halt the pathogenesis of renal injury. Prophylactic treatment with a combination of fCNT/siMep1band fCNT/siTrp53significantly improved progression-free survival compared to controls via a mechanism that required concurrent reduction of meprin-1β and p53 expression. The fCNT/siRNA was well tolerated, and no toxicological consequences were observed in murine models. Toward clinical application of this platform, fCNTs were evaluated for the first time in nonhuman primates. The rapid and kidney-specific pharmacokinetic profile of fCNT in primates was comparable to what was observed in mice and suggests that this approach is amenable for use in humans. The nanocarbon-mediated delivery of siRNA provides a therapeutic means for the prevention of AKI to safely overcome the persistent barrier of nephrotoxicity during medical intervention.
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Affiliation(s)
- Simone Alidori
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Nima Akhavein
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Daniel L J Thorek
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Katja Behling
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Yevgeniy Romin
- Molecular Cytology Core Facility, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Dawn Queen
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Bradley J Beattie
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Katia Manova-Todorova
- Molecular Cytology Core Facility, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Magnus Bergkvist
- College of Nanoscale Science and Engineering, University at Albany, Albany, NY 12203, USA
| | - David A Scheinberg
- Department of Molecular Pharmacology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA. Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA. Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Michael R McDevitt
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA. Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA.
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Conti M, Eriksson L. Physics of pure and non-pure positron emitters for PET: a review and a discussion. EJNMMI Phys 2016; 3:8. [PMID: 27271304 PMCID: PMC4894854 DOI: 10.1186/s40658-016-0144-5] [Citation(s) in RCA: 197] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 05/31/2015] [Indexed: 01/09/2023] Open
Abstract
With the increased interest in new PET tracers, gene-targeted therapy, immunoPET, and theranostics, other radioisotopes will be increasingly used in clinical PET scanners, in addition to 18F. Some of the most interesting radioisotopes with prospective use in the new fields are not pure short-range β+ emitters but can be associated with gamma emissions in coincidence with the annihilation radiation (prompt gamma), gamma-gamma cascades, intense Bremsstrahlung radiation, high-energy positrons that may escape out of the patient skin, and high-energy gamma rays that result in some e+/e− pair production. The high level of sophistication in data correction and excellent quantitative accuracy that has been reached for 18F in recent years can be questioned by these effects. In this work, we review the physics and the scientific literature and evaluate the effect of these additional phenomena on the PET data for each of a series of radioisotopes: 11C, 13N, 15O, 18F, 64Cu, 68Ga, 76Br, 82Rb, 86Y, 89Zr, 90Y, and 124I. In particular, we discuss the present complications arising from the prompt gammas, and we review the scientific literature on prompt gamma correction. For some of the radioisotopes considered in this work, prompt gamma correction is definitely needed to assure acceptable image quality, and several approaches have been proposed in recent years. Bremsstrahlung photons and 176Lu background were also evaluated.
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Affiliation(s)
- Maurizio Conti
- Siemens Healthcare Molecular Imaging, Knoxville, TN, USA.
| | - Lars Eriksson
- Siemens Healthcare Molecular Imaging, Knoxville, TN, USA.,Department of Physics, University of Stockholm, Stockholm, Sweden.,Karolinska Institute, Stockholm, Sweden.,Scintillation Material Research Center, University of Tennessee, Knoxville, TN, USA
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15
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Lin HH, Chuang KS, Chen SY, Jan ML. Recovering the triple coincidence of non-pure positron emitters in preclinical PET. Phys Med Biol 2016; 61:1904-31. [DOI: 10.1088/0031-9155/61/5/1904] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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16
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Cheal SM, Xu H, Guo HF, Lee SG, Punzalan B, Chalasani S, Fung EK, Jungbluth A, Zanzonico PB, Carrasquillo JA, O'Donoghue J, Smith-Jones PM, Wittrup KD, Cheung NKV, Larson SM. Theranostic pretargeted radioimmunotherapy of colorectal cancer xenografts in mice using picomolar affinity ⁸⁶Y- or ¹⁷⁷Lu-DOTA-Bn binding scFv C825/GPA33 IgG bispecific immunoconjugates. Eur J Nucl Med Mol Imaging 2015; 43:925-937. [PMID: 26596724 DOI: 10.1007/s00259-015-3254-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 11/02/2015] [Indexed: 12/25/2022]
Abstract
PURPOSE GPA33 is a colorectal cancer (CRC) antigen with unique retention properties after huA33-mediated tumor targeting. We tested a pretargeted radioimmunotherapy (PRIT) approach for CRC using a tetravalent bispecific antibody with dual specificity for GPA33 tumor antigen and DOTA-Bn-(radiolanthanide metal) complex. METHODS PRIT was optimized in vivo by titrating sequential intravenous doses of huA33-C825, the dextran-based clearing agent, and the C825 haptens (177)Lu-or (86)Y-DOTA-Bn in mice bearing the SW1222 subcutaneous (s.c.) CRC xenograft model. RESULTS Using optimized PRIT, therapeutic indices (TIs) for tumor radiation-absorbed dose of 73 (tumor/blood) and 12 (tumor/kidney) were achieved. Estimated absorbed doses (cGy/MBq) to tumor, blood, liver, spleen, and kidney for single-cycle PRIT were 65.8, 0.9 (TI 73), 6.3 (TI 10), 6.6 (TI 10), and 5.3 (TI 12), respectively. Two cycles of PRIT (66.6 or 111 MBq (177)Lu-DOTA-Bn) were safe and effective, with a complete response of established s.c. tumors (100 - 700 mm(3)) in nine of nine mice, with two mice alive without recurrence at >140 days. Tumor log kill in this model was estimated to be 2.1 - 3.0 based on time to 500-mm(3) tumor recurrence. In addition, PRIT dosimetry/diagnosis was performed by PET imaging of the positron-emitting DOTA hapten (86)Y-DOTA-Bn. CONCLUSION We have developed anti-GPA33 PRIT as a triple-step theranostic strategy for preclinical detection, dosimetry, and safe targeted radiotherapy of established human colorectal mouse xenografts.
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Affiliation(s)
- Sarah M Cheal
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Molecular Pharmacology and Chemistry Program, Memorial Sloan Kettering Cancer Center, 415 E. 68th Street, Z-2064, New York, NY, 10065, USA
| | - Hong Xu
- Department of Pediatrics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Hong-Fen Guo
- Department of Pediatrics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Sang-Gyu Lee
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Molecular Pharmacology and Chemistry Program, Memorial Sloan Kettering Cancer Center, 415 E. 68th Street, Z-2064, New York, NY, 10065, USA
| | - Blesida Punzalan
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Molecular Pharmacology and Chemistry Program, Memorial Sloan Kettering Cancer Center, 415 E. 68th Street, Z-2064, New York, NY, 10065, USA
| | - Sandhya Chalasani
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Edward K Fung
- Molecular Pharmacology and Chemistry Program, Memorial Sloan Kettering Cancer Center, 415 E. 68th Street, Z-2064, New York, NY, 10065, USA.,Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Achim Jungbluth
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Pat B Zanzonico
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Jorge A Carrasquillo
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Joseph O'Donoghue
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Peter M Smith-Jones
- Department of Psychiatry and Behavioral Science, Stony Brook University, Stony Brook, NY, USA.,Department of Radiology, Stony Brook University, Stony Brook, NY, USA
| | - K Dane Wittrup
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.,Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Nai-Kong V Cheung
- Molecular Pharmacology and Chemistry Program, Memorial Sloan Kettering Cancer Center, 415 E. 68th Street, Z-2064, New York, NY, 10065, USA.,Department of Pediatrics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Steven M Larson
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA. .,Molecular Pharmacology and Chemistry Program, Memorial Sloan Kettering Cancer Center, 415 E. 68th Street, Z-2064, New York, NY, 10065, USA.
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17
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Braad PEN, Hansen SB, Høilund-Carlsen PF. Impact of high (131)I-activities on quantitative (124)I-PET. Phys Med Biol 2015; 60:5297-312. [PMID: 26108201 DOI: 10.1088/0031-9155/60/13/5297] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Peri-therapeutic (124)I-PET/CT is of interest as guidance for radioiodine therapy. Unfortunately, image quality is complicated by dead time effects and increased random coincidence rates from high (131)I-activities. A series of phantom experiments with clinically relevant (124)I/(131)I-activities were performed on a clinical PET/CT-system. Noise equivalent count rate (NECR) curves and quantitation accuracy were determined from repeated scans performed over several weeks on a decaying NEMA NU-2 1994 cylinder phantom initially filled with 25 MBq (124)I and 1250 MBq (131)I. Six spherical inserts with diameters 10-37 mm were filled with (124)I (0.45 MBq ml(-1)) and (131)I (22 MBq ml(-1)) and placed inside the background of the NEMA/IEC torso phantom. Contrast recovery, background variability and the accuracy of scatter and attenuation corrections were assessed at sphere-to-background activity ratios of 20, 10 and 5. Results were compared to pure (124)I-acquisitions. The quality of (124)I-PET images in the presence of high (131)I-activities was good and image quantification unaffected except at very high count rates. Quantitation accuracy and contrast recovery were uninfluenced at (131)I-activities below 1000 MBq, whereas image noise was slightly increased. The NECR peaked at 550 MBq of (131)I, where it was 2.8 times lower than without (131)I in the phantom. Quantitative peri-therapeutic (124)I-PET is feasible.
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Affiliation(s)
- P E N Braad
- Department of Nuclear Medicine Odense University Hospital Sdr. Boulevard 29 DK-5000 Odense C, Denmark
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18
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19
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Braad PEN, Hansen SB, Thisgaard H, Høilund-Carlsen PF. PET imaging with the non-pure positron emitters:55Co,86Y and124I. Phys Med Biol 2015; 60:3479-97. [DOI: 10.1088/0031-9155/60/9/3479] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Moreau M, Buvat I, Ammour L, Chouin N, Kraeber-Bodéré F, Chérel M, Carlier T. Assessment of a fully 3D Monte Carlo reconstruction method for preclinical PET with iodine-124. Phys Med Biol 2015; 60:2475-91. [PMID: 25739884 DOI: 10.1088/0031-9155/60/6/2475] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Iodine-124 is a radionuclide well suited to the labeling of intact monoclonal antibodies. Yet, accurate quantification in preclinical imaging with I-124 is challenging due to the large positron range and a complex decay scheme including high-energy gammas. The aim of this work was to assess the quantitative performance of a fully 3D Monte Carlo (MC) reconstruction for preclinical I-124 PET. The high-resolution small animal PET Inveon (Siemens) was simulated using GATE 6.1. Three system matrices (SM) of different complexity were calculated in addition to a Siddon-based ray tracing approach for comparison purpose. Each system matrix accounted for a more or less complete description of the physics processes both in the scanned object and in the PET scanner. One homogeneous water phantom and three heterogeneous phantoms including water, lungs and bones were simulated, where hot and cold regions were used to assess activity recovery as well as the trade-off between contrast recovery and noise in different regions. The benefit of accounting for scatter, attenuation, positron range and spurious coincidences occurring in the object when calculating the system matrix used to reconstruct I-124 PET images was highlighted. We found that the use of an MC SM including a thorough modelling of the detector response and physical effects in a uniform water-equivalent phantom was efficient to get reasonable quantitative accuracy in homogeneous and heterogeneous phantoms. Modelling the phantom heterogeneities in the SM did not necessarily yield the most accurate estimate of the activity distribution, due to the high variance affecting many SM elements in the most sophisticated SM.
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Affiliation(s)
- M Moreau
- CRCNA, INSERM, University of Nantes, UMR 892, Nantes, France. AMaROC, National Veterinary School ONIRIS, Nantes, France
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21
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Cal-González J, Lage E, Herranz E, Vicente E, Udias JM, Moore SC, Park MA, Dave SR, Parot V, Herraiz JL. Simulation of triple coincidences in PET. Phys Med Biol 2015; 60:117-36. [PMID: 25479147 DOI: 10.1088/0031-9155/60/1/117] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although current PET scanners are designed and optimized to detect double coincidence events, there is a significant amount of triple coincidences in any PET acquisition. Triple coincidences may arise from causes such as: inter-detector scatter (IDS), random triple interactions (RT), or the detection of prompt gamma rays in coincidence with annihilation photons when non-pure positron-emitting radionuclides are used (β(+)γ events). Depending on the data acquisition settings of the PET scanner, these triple events are discarded or processed as a set of double coincidences if the energy of the three detected events is within the scanner's energy window. This latter option introduces noise in the data, as at most, only one of the possible lines-of-response defined by triple interactions corresponds to the line along which the decay occurred. Several novel works have pointed out the possibility of using triple events to increase the sensitivity of PET scanners or to expand PET imaging capabilities by allowing differentiation between radiotracers labeled with non-pure and pure positron-emitting radionuclides. In this work, we extended the Monte Carlo simulator PeneloPET to assess the proportion of triple coincidences in PET acquisitions and to evaluate their possible applications. We validated the results of the simulator against experimental data acquired with a modified version of a commercial preclinical PET/CT scanner, which was enabled to acquire and process triple-coincidence events. We used as figures of merit the energy spectra for double and triple coincidences and the triples-to-doubles ratio for different energy windows and radionuclides. After validation, the simulator was used to predict the relative quantity of triple-coincidence events in two clinical scanners assuming different acquisition settings. Good agreement between simulations and preclinical experiments was found, with differences below 10% for most of the observables considered. For clinical scanners and pure positron emitters, we found that around 10% of the processed double events come from triple coincidences, increasing this ratio substantially for non-pure emitters (around 25% for (124)I and > 50% for (86)Y). For radiotracers labeled with (18)F we found that the relative quantity of IDS events in standard acquisitions is around 18% for the preclinical scanner and between 14 and 22% for the clinical scanners. For non-pure positron emitters like (124)I, we found a β(+)γ triples-to-doubles ratio of 2.5% in the preclinical scanner and of up to 4% in the clinical scanners.
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Affiliation(s)
- J Cal-González
- Grupo de Física Nuclear, Dpto. de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, CEI Moncloa, Spain
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22
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Cal-González J, Lage E, Herranz E, Vicente E, Udias JM, Moore SC, Park MA, Dave SR, Parot V, Herraiz JL. Simulation of triple coincidences in PET. Phys Med Biol 2014. [DOI: https://doi.org/10.1088/0031-9155/60/1/117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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23
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Beattie BJ, Pentlow KS, O'Donoghue J, Humm JL. A recommendation for revised dose calibrator measurement procedures for 89Zr and 124I. PLoS One 2014; 9:e106868. [PMID: 25202987 PMCID: PMC4159273 DOI: 10.1371/journal.pone.0106868] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 08/11/2014] [Indexed: 11/19/2022] Open
Abstract
Because of their chemical properties and multiday half lives, iodine-124 and zirconium-89 are being used in a growing number of PET imaging studies. Some aspects of their quantitation, however, still need attention. For (89)Zr the PET images should, in principle, be as quantitatively accurate as similarly reconstructed 18F measurements. We found, however, that images of a 20 cm well calibration phantom containing (89)Zr underestimated the activity by approximately 10% relative to a dose calibrator measurement (Capintec CRC-15R) using a published calibration setting number of 465. PET images of (124)I, in contrast, are complicated by the contribution of decays in cascade that add spurious coincident events to the PET data. When these cascade coincidences are properly accounted for, quantitatively accurate images should be possible. We found, however, that even with this correction we still encountered what appeared to be a large variability in the accuracy of the PET images when compared to dose calibrator measurements made using the calibration setting number, 570, recommended by Capintec. We derive new calibration setting numbers for (89)Zr and (124)I based on their 511 keV photon peaks as measured on an HPGe detector. The peaks were calibrated relative to an 18F standard, the activity level of which was precisely measured in a dose calibrator under well-defined measurement conditions. When measuring (89)Zr on a Capintec CRC-15R we propose the use of calibration setting number 517. And for (124)I, we recommend the use of a copper filter surrounding the sample and the use of calibration setting number 494. The new dose calibrator measurement procedures we propose will result in more consistent and accurate radioactivity measurements of (89)Zr and (124)I. These and other positron emitting radionuclides can be accurately calibrated relative to 18F based on measurements of their 511 keV peaks and knowledge of their relative positron abundances.
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Affiliation(s)
- Bradley J. Beattie
- Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
- * E-mail:
| | - Keith S. Pentlow
- Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Joseph O'Donoghue
- Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - John L. Humm
- Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
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Abstract
Personalized dosimetry in radionuclide therapy has gained much attention in recent years. This attention has also an impact on peptide receptor radionuclide therapy (PRRT). This article reviews the PET-based imaging techniques that can be used for pretherapeutic prediction of doses in PRRT. More specifically the usage of (86)Y, (90)Y, (68)Ga, and (44)Sc are discussed: their characteristics for PET acquisition, the available peptides for labeling, the specifics of the imaging protocols, and the experiences gained from phantom and clinical studies. These techniques are evaluated with regard to their usefulness for dosimetry predictions in PRRT, and future perspectives are discussed.
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25
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Is the image quality of I-124-PET impaired by an automatic correction of prompt gammas? PLoS One 2013; 8:e71729. [PMID: 24014105 PMCID: PMC3754939 DOI: 10.1371/journal.pone.0071729] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 07/08/2013] [Indexed: 11/19/2022] Open
Abstract
Objectives The aim of this study is to evaluate the quality of I-124 PET images with and without prompt gamma compensation (PGC) by comparing the recovery coefficients (RC), the signal to noise ratios (SNR) and the contrast to F-18 and Ga-68. Furthermore, the influence of the PGC on the quantification and image quality is evaluated. Methods For measuring the image quality the NEMA NU2-2001 PET/SPECT-Phantom was used containing 6 spheres with a diameter between 10 mm and 37 mm placed in water with different levels of background activity. Each sphere was filled with the same activity concentration measured by an independently cross-calibrated dose calibrator. The “hot” sources were acquired with a full 3D PET/CT (Biograph mCT®, Siemens Medical USA). Acquisition times were 2 min for F-18 and Ga-68, and 10 min for I-124. For reconstruction an OSEM algorithm was applied. For I-124 the images were reconstructed with and without PGC. For the calculation of the RCs the activity concentrations in each sphere were determined; in addition, the influence of the background correction was studied. Results The RCs of Ga-68 are the smallest (79%). I-124 reaches similar RCs (87% with PGC, 84% without PGC) as F-18 (84%). showing that the quantification of I-124 images is similar to F-18 and slightly better than Ga-68. With background activity the contrast of the I-124 PGC images is similar to Ga-68 and F-18 scans. There was lower background activity in the I-124 images without PGC, which probably originates from an overcorrection of the scatter contribution. Consequently, the contrast without PGC was much higher than with PGC. As a consequence PGC should be used for I-124. Conclusions For I-124 there is only a slight influence on the quantification depending on the use of the PGC. However, there are considerable differences with respect to I-124 image quality.
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Frey EC, Humm JL, Ljungberg M. Accuracy and precision of radioactivity quantification in nuclear medicine images. Semin Nucl Med 2012; 42:208-18. [PMID: 22475429 PMCID: PMC3586419 DOI: 10.1053/j.semnuclmed.2011.11.003] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The ability to reliably quantify activity in nuclear medicine has a number of increasingly important applications. Dosimetry for targeted therapy treatment planning or for approval of new imaging agents requires accurate estimation of the activity in organs, tumors, or voxels at several imaging time points. Another important application is the use of quantitative metrics derived from images, such as the standard uptake value commonly used in positron emission tomography (PET), to diagnose and follow treatment of tumors. These measures require quantification of organ or tumor activities in nuclear medicine images. However, there are a number of physical, patient, and technical factors that limit the quantitative reliability of nuclear medicine images. There have been a large number of improvements in instrumentation, including the development of hybrid single-photon emission computed tomography/computed tomography and PET/computed tomography systems, and reconstruction methods, including the use of statistical iterative reconstruction methods, which have substantially improved the ability to obtain reliable quantitative information from planar, single-photon emission computed tomography, and PET images.
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Affiliation(s)
- Eric C. Frey
- Russell H. Morgan Department of Radiology and Radiological Science Johns Hopkins University, Baltimore, Maryland
| | - John L. Humm
- Memorial Sloan-Kettering Cancer Center, New York
| | - Michael Ljungberg
- Department of Medical Radiation Physics, Clinical Sciences, Lund, Lund University, Lund, Sweden
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Anizan N, Carlier T, Hindorf C, Barbet J, Bardiès M. dAcquisition setting optimization and quantitative imaging for 124I studies with the Inveon microPET-CT system. EJNMMI Res 2012; 2:7. [PMID: 22330760 PMCID: PMC3311594 DOI: 10.1186/2191-219x-2-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 02/13/2012] [Indexed: 11/23/2022] Open
Abstract
Background Noninvasive multimodality imaging is essential for preclinical evaluation of the biodistribution and pharmacokinetics of radionuclide therapy and for monitoring tumor response. Imaging with nonstandard positron-emission tomography [PET] isotopes such as 124I is promising in that context but requires accurate activity quantification. The decay scheme of 124I implies an optimization of both acquisition settings and correction processing. The PET scanner investigated in this study was the Inveon PET/CT system dedicated to small animal imaging. Methods The noise equivalent count rate [NECR], the scatter fraction [SF], and the gamma-prompt fraction [GF] were used to determine the best acquisition parameters for mouse- and rat-sized phantoms filled with 124I. An image-quality phantom as specified by the National Electrical Manufacturers Association NU 4-2008 protocol was acquired and reconstructed with two-dimensional filtered back projection, 2D ordered-subset expectation maximization [2DOSEM], and 3DOSEM with maximum a posteriori [3DOSEM/MAP] algorithms, with and without attenuation correction, scatter correction, and gamma-prompt correction (weighted uniform distribution subtraction). Results Optimal energy windows were established for the rat phantom (390 to 550 keV) and the mouse phantom (400 to 590 keV) by combining the NECR, SF, and GF results. The coincidence time window had no significant impact regarding the NECR curve variation. Activity concentration of 124I measured in the uniform region of an image-quality phantom was underestimated by 9.9% for the 3DOSEM/MAP algorithm with attenuation and scatter corrections, and by 23% with the gamma-prompt correction. Attenuation, scatter, and gamma-prompt corrections decreased the residual signal in the cold insert. Conclusions The optimal energy windows were chosen with the NECR, SF, and GF evaluation. Nevertheless, an image quality and an activity quantification assessment were required to establish the most suitable reconstruction algorithm and corrections for 124I small animal imaging.
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Affiliation(s)
- Nadège Anizan
- Institut National de la Santé et de la Recherche Médicale (INSERM) U-892, Nantes, 44035, France.
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28
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van Elmbt L, Vandenberghe S, Walrand S, Pauwels S, Jamar F. Comparison of yttrium-90 quantitative imaging by TOF and non-TOF PET in a phantom of liver selective internal radiotherapy. Phys Med Biol 2011; 56:6759-77. [PMID: 21970976 DOI: 10.1088/0031-9155/56/21/001] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The aim of this study is to determine the feasibility of achieving quantitative measurement in (90)Y-microspheres liver selective internal radiotherapy (SIRT) by imaging (90)Y with a conventional non-time of flight (TOF) PET device. Instead of the bremsstrahlung x-rays of the β-decay, the low branch of e(-)- e(+) pair production in the (90)Y-decay was used. The activity distribution in a phantom-simulated liver SIRT was obtained by direct (90)Y-PET imaging. We tested a LYSO TOF PET and two GSO and BGO non-TOF PET scanners using a 3.6-l cylindrical phantom filled with the (90)Y solution containing two sets of hot and cold spheres. The best hot contrast was obtained with the LYSO TOF. It was close to the expected value and remained constant, even for short acquisition times. The LYSO non-TOF was about 10% lower. The GSO performed similarly but degraded for shorter times whilst the BGO was the worst with 40% loss. For the cold spheres, the LYSO TOF and the GSO provided the best results, while the LYSO non-TOF and the BGO were the worst. (90)Y PET imaging in liver SIRT is achievable with LYSO TOF. Conventional LYSO and GSO show a loss of contrast and require longer acquisition times. BGO imaging is not feasible for dosimetry calculation.
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Affiliation(s)
- Larry van Elmbt
- Department of Nuclear Medicine, Université Catholique de Louvain, Brussels, Belgium.
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Lubberink M, Herzog H. Quantitative imaging of 124I and 86Y with PET. Eur J Nucl Med Mol Imaging 2011; 38 Suppl 1:S10-8. [PMID: 21484385 PMCID: PMC3098993 DOI: 10.1007/s00259-011-1768-2] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 02/22/2011] [Indexed: 12/02/2022]
Abstract
The quantitative accuracy and image quality of positron emission tomography (PET) measurements with 124I and 86Y is affected by the prompt emission of gamma radiation and positrons in their decays, as well as the higher energy of the emitted positrons compared to those emitted by 18F. PET scanners cannot distinguish between true coincidences, involving two 511-keV annihilation photons, and coincidences involving one annihilation photon and a prompt gamma, if the energy of this prompt gamma is within the energy window of the scanner. The current review deals with a number of aspects of the challenge this poses for quantitative PET imaging. First, the effect of prompt gamma coincidences on quantitative accuracy of PET images is discussed and a number of suggested corrections are described. Then, the effect of prompt gamma coincidences and the increased singles count rates due to gamma radiation on the count rate performance of PET is addressed, as well as possible improvements based on modification of the scanner’s energy windows. Finally, the effect of positron energy on spatial resolution and recovery is assessed. The methods presented in this overview aim to overcome the challenges associated with the decay characteristics of 124I and 86Y. Careful application of the presented correction methods can allow for quantitatively accurate images with improved image contrast.
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Affiliation(s)
- Mark Lubberink
- Department of Medical Physics and PET Centre, Uppsala University Hospital, Uppsala, Sweden.
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Walrand S, Flux GD, Konijnenberg MW, Valkema R, Krenning EP, Lhommel R, Pauwels S, Jamar F. Dosimetry of yttrium-labelled radiopharmaceuticals for internal therapy: 86Y or 90Y imaging? Eur J Nucl Med Mol Imaging 2011; 38 Suppl 1:S57-68. [DOI: 10.1007/s00259-011-1771-7] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Accepted: 02/22/2011] [Indexed: 12/31/2022]
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Tu Z, Efange SMN, Xu J, Li S, Jones LA, Parsons SM, Mach RH. Synthesis and in vitro and in vivo evaluation of 18F-labeled positron emission tomography (PET) ligands for imaging the vesicular acetylcholine transporter. J Med Chem 2010; 52:1358-69. [PMID: 19203271 DOI: 10.1021/jm8012344] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A new class of vesicular acetylcholine transporter inhibitor that incorporates a carbonyl group into the benzovesamicol structure was synthesized, and analogues were evaluated in vitro. (+/-)-trans-2-Hydroxy-3-(4-(4-[(18)F]fluorobenzoyl)piperidino)tetralin (9e) has K(i) values of 2.70 nM for VAChT, 191 nM for sigma(1), and 251 nM for sigma(2). The racemic precursor (9d) was resolved via chiral HPLC, and (+/-)-[(18)F]9e, (-)-[(18)F]9e, and (+)-[(18)F]9e were respectively radiolabeled via microwave irradiation of the appropriate precursors with [(18)F]/F(-) and Kryptofix/K(2)CO(3) in DMSO with radiochemical yields of approximately 50-60% and specific activities of >2000 mCi/micromol. (-)-[(18)F]9e uptake in rat brain was consistent with in vivo selectivity for the VAChT with an initial uptake of 0.911 %ID/g in rat striatum and a striatum/cerebellum ratio of 1.88 at 30 min postinjection (p.i.). MicroPET imaging of macaques demonstrated a 2.1 ratio of (-)-[(18)F]9e in putamen versus cerebellum at 2 h p.i. (-)-[(18)F]9e has potential to be a PET tracer for clinical imaging of the VAChT.
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Affiliation(s)
- Zhude Tu
- Division of Radiological Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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Lhommel R, van Elmbt L, Goffette P, Van den Eynde M, Jamar F, Pauwels S, Walrand S. Feasibility of 90Y TOF PET-based dosimetry in liver metastasis therapy using SIR-Spheres. Eur J Nucl Med Mol Imaging 2010; 37:1654-62. [DOI: 10.1007/s00259-010-1470-9] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Accepted: 04/06/2010] [Indexed: 12/27/2022]
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Koehler L, Gagnon K, McQuarrie S, Wuest F. Iodine-124: a promising positron emitter for organic PET chemistry. Molecules 2010; 15:2686-718. [PMID: 20428073 PMCID: PMC6257279 DOI: 10.3390/molecules15042686] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 04/07/2010] [Accepted: 04/09/2010] [Indexed: 11/16/2022] Open
Abstract
The use of radiopharmaceuticals for molecular imaging of biochemical and physiological processes in vivo has evolved into an important diagnostic tool in modern nuclear medicine and medical research. Positron emission tomography (PET) is currently the most sophisticated molecular imaging methodology, mainly due to the unrivalled high sensitivity which allows for the studying of biochemistry in vivo on the molecular level. The most frequently used radionuclides for PET have relatively short half-lives (e.g. 11C: 20.4 min; 18F: 109.8 min) which may limit both the synthesis procedures and the time frame of PET studies. Iodine-124 (124I, t1/2 = 4.2 d) is an alternative long-lived PET radionuclide attracting increasing interest for long term clinical and small animal PET studies. The present review gives a survey on the use of 124I as promising PET radionuclide for molecular imaging. The first part describes the production of 124I. The second part covers basic radiochemistry with 124I focused on the synthesis of 124I-labeled compounds for molecular imaging purposes. The review concludes with a summary and an outlook on the future prospective of using the long-lived positron emitter 124I in the field of organic PET chemistry and molecular imaging.
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Affiliation(s)
- Lena Koehler
- Institute of Radiopharmacy, Research Center Dresden-Rossendorf, Dresden, Germany; E-Mail: (L.K.)
| | - Katherine Gagnon
- Department of Physics, University of Alberta, Edmonton, Canada; E-Mail: (K.G.)
| | - Steve McQuarrie
- Department of Oncology, University of Alberta, Edmonton, Canada; E-Mail: (S.M.)
| | - Frank Wuest
- Department of Oncology, University of Alberta, Edmonton, Canada; E-Mail: (S.M.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1 780 989 8150; Fax: +1 780 432 8483
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Esteves FP, Nye JA, Khan A, Folks RD, Halkar RK, Garcia EV, Schuster DM, Lerakis S, Raggi P, Votaw JR. Prompt-gamma compensation in Rb-82 myocardial perfusion 3D PET/CT. J Nucl Cardiol 2010; 17:247-53. [PMID: 19937169 DOI: 10.1007/s12350-009-9170-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2009] [Accepted: 11/13/2009] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To compare the diagnostic accuracy of Rb-82 myocardial perfusion three-dimensional (3D) PET with and without prompt-gamma compensation (PGC). METHODS AND RESULTS Retrospective, single center study of 76 patients who had rest and adenosine stress Rb-82 myocardial perfusion 3D PET. All studies were acquired using a Siemens Biograph-40 PET/CT scanner and were reconstructed with and without PGC. Fifty-seven patients (mean age 63 +/- 11 years, 26 men) had coronary angiography within 40 days of Rb-82 imaging. Nineteen patients (mean age 43 +/- 7 years, 10 men) had low likelihood of coronary artery disease (CAD). All PET images were scored by consensus of two blinded readers on a standard 5-point scale using a 17-segment left ventricular model. A normal PET test was defined as a summed stress score of less than four. Obstructive CAD at coronary angiography was used as the gold-standard and was defined as luminal stenoses > or =50% in one or more major coronary arteries. The prevalence of obstructive disease at coronary angiography was 68% (39/57). The mean summed stress score was 12 +/- 12 for PGC images and was 18 +/- 14 for non-PGC images. Sensitivity and specificity for obstructive CAD were 90% (95% CI 88-99) and 72% (95% CI 52-93) for PGC images and 95% (95% CI 88-100) and 22% (95% CI 3-41) for non-PGC images. CONCLUSION PGC in Rb-82 3D PET improves the specificity for obstructive CAD at coronary angiography with no significant loss in sensitivity.
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Affiliation(s)
- Fabio P Esteves
- Department of Radiology, Emory University School of Medicine, 1364 Clifton Road, NE, Atlanta, GA 30322, USA.
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Jentzen W. Experimental investigation of factors affecting the absolute recovery coefficients in iodine-124 PET lesion imaging. Phys Med Biol 2010; 55:2365-98. [DOI: 10.1088/0031-9155/55/8/016] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Disselhorst JA, Brom M, Laverman P, Slump CH, Boerman OC, Oyen WJ, Gotthardt M, Visser EP. Image-Quality Assessment for Several Positron Emitters Using the NEMA NU 4-2008 Standards in the Siemens Inveon Small-Animal PET Scanner. J Nucl Med 2010; 51:610-7. [DOI: 10.2967/jnumed.109.068858] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Zhu X, El Fakhri G. Monte Carlo modeling of cascade gamma rays in (86)Y PET imaging: preliminary results. Phys Med Biol 2009; 54:4181-93. [PMID: 19521011 DOI: 10.1088/0031-9155/54/13/014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
(86)Y is a PET agent that could be used as an ideal surrogate to allow personalized dosimetry in (90)Y radionuclide therapy. However, (86)Y also emits cascade gamma rays. We have developed a Monte Carlo program based on SimSET (Simulation System for Emission Tomography) to model cascade gamma rays in PET imaging. The new simulation was validated with the GATE simulation package. Agreements within 15% were found in spatial resolution, apparent scatter fraction (ratio of coincidences outside peak regions in line source sinograms), single and coincidence statistics and detected photons energy distribution within the PET energy window. A discrepancy of 20% was observed in the absolute scatter fraction, likely caused by differences in the tracking of higher energy cascade gamma photons. On average, the new simulation is 6 times faster than GATE, and the computing time can be further improved by using variance reduction techniques currently available in SimSET. Comparison with phantom acquisitions showed agreements in spatial resolutions and the general shape of projection profiles; however, the standard scatter correction method on the scanner is not directly applicable to (86)Y PET as it leads to incorrect scatter fractions. The new simulation was used to characterize (86)Y PET. Compared with conventional (18)F PET, in which major contamination at low count rates comes from scattered events, cascade gamma-involved events are more important in (86)Y PET. The two types of contaminations have completely different distribution patterns, which should be considered for the corrections of their effects. Our approach will be further improved in the future in the modeling of random coincidences and tracking of high-energy photons, and simulation results will be used for the development of correction methods in (86)Y PET.
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Affiliation(s)
- Xuping Zhu
- Radiology Department, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, MA, USA.
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Surti S, Scheuermann R, Karp JS. Correction technique for cascade gammas in I-124 imaging on a fully-3D, Time-of-Flight PET Scanner. IEEE TRANSACTIONS ON NUCLEAR SCIENCE 2009; 56:653-660. [PMID: 19662100 PMCID: PMC2721226 DOI: 10.1109/tns.2008.2011805] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
It has been shown that I-124 PET imaging can be used for accurate dose estimation in radio-immunotherapy techniques. However, I-124 is not a pure positron emitter, leading to two types of coincidence events not typically encountered: increased random coincidences due to non-annihilation cascade photons, and true coincidences between an annihilation photon and primarily a coincident 602 keV cascade gamma (true coincidence gamma-ray background). The increased random coincidences are accurately estimated by the delayed window technique. Here we evaluate the radial and time distributions of the true coincidence gamma-ray background in order to correct and accurately estimate lesion uptake for I-124 imaging in a time-of-flight (TOF) PET scanner. We performed measurements using a line source of activity placed in air and a water-filled cylinder, using F-18 and I-124 radio-isotopes. Our results show that the true coincidence gamma-ray backgrounds in I-124 have a uniform radial distribution, while the time distribution is similar to the scattered annihilation coincidences. As a result, we implemented a TOF-extended single scatter simulation algorithm with a uniform radial offset in the tail-fitting procedure for accurate correction of TOF data in I-124 imaging. Imaging results show that the contrast recovery for large spheres in a uniform activity background is similar in F-18 and I-124 imaging. There is some degradation in contrast recovery for small spheres in I-124, which is explained by the increased positron range, and reduced spatial resolution, of I-124 compared to F-18. Our results show that it is possible to perform accurate TOF based corrections for I-124 imaging.
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Affiliation(s)
- Suleman Surti
- Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104 USA (telephone: 215-662-7214, e-mail: )
| | - Ryan Scheuermann
- Department of Physics, University of Pennsylvania, Philadelphia, PA 19104 USA (telephone: 215-662-7792, e-mail: )
| | - Joel S. Karp
- Departments of Radiology and Physics, University of Pennsylvania, Philadelphia, PA 19104 USA (telephone: 215-662-3073, e-mail: )
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Nayak TK, Brechbiel MW. Radioimmunoimaging with longer-lived positron-emitting radionuclides: potentials and challenges. Bioconjug Chem 2009; 20:825-41. [PMID: 19125647 PMCID: PMC3397469 DOI: 10.1021/bc800299f] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Radioimmunoimaging and therapy has been an area of interest for several decades. Steady progress has been made toward clinical translation of radiolabeled monoclonal antibodies for diagnosis and treatment of diseases. Tremendous advances have been made in imaging technologies such as positron emission tomography (PET). However, these advances have so far eluded routine translation into clinical radioimmunoimaging applications due to the mismatch between the short half-lives of routinely used positron-emitting radionuclides such as (18)F versus the pharmacokinetics of most intact monoclonal antibodies of interest. The lack of suitable positron-emitting radionuclides that match the pharmacokinetics of intact antibodies has generated interest in exploring the use of longer-lived positron emitters that are more suitable for radioimmunoimaging and dosimetry applications with intact monoclonal antibodies. In this review, we examine the opportunities and challenges of radioimmunoimaging with select longer-lived positron-emitting radionuclides such as (124)I, (89)Zr, and (86)Y with respect to radionuclide production, ease of radiolabeling intact antibodies, imaging characteristics, radiation dosimetry, and clinical translation potential.
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Affiliation(s)
- Tapan K. Nayak
- Radioimmune & Inorganic Chemistry Section, Radiation Oncology Branch, National Cancer Institute, National Institute of Health, Bethesda, MD-20892, USA
| | - Martin W. Brechbiel
- Radioimmune & Inorganic Chemistry Section, Radiation Oncology Branch, National Cancer Institute, National Institute of Health, Bethesda, MD-20892, USA
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Grewal RK, Lubberink M, Pentlow KS, Larson SM. The Role of Iodine-124-Positron Emission Tomography Imaging in the Management of Patients with Thyroid Cancer. PET Clin 2008; 2:313-20. [PMID: 27158012 DOI: 10.1016/j.cpet.2008.05.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Molecular imaging is the visualization, characterization, and measurement of biologic processes at the molecular and cellular levels in human beings and other living systems. In thyroid cancer, this includes imaging iodine transport, which is active in about 80% of well-differentiated thyroid malignancies. Iodine-124 imaging with positron emission tomography (I-124-PET) is ideal for this purpose because PET provides tomographic images with spatial and contrast resolution. Because iodine-131 is the mainstay for therapy in thyroid cancer, and because success or failure of therapy depends on the degree of iodine uptake by the tumor cells, I-124-PET imaging will increasingly act as a surrogate for this treatment. This approach may serve as a model for individualized therapeutic interventions for many other malignant and nonmalignant diseases.
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Affiliation(s)
- Ravinder K Grewal
- Division of Nuclear Medicine, Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
| | - Mark Lubberink
- Department of Nuclear Medicine and PET Research, VU University Medical Centre, PO Box 7057, 1007 MB Amsterdam, The Netherlands
| | - Keith S Pentlow
- Nuclear Medicine Physics, Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Steven M Larson
- Division of Nuclear Medicine, Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
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Lewis JS, Laforest R, Dehdashti F, Grigsby PW, Welch MJ, Siegel BA. An imaging comparison of 64Cu-ATSM and 60Cu-ATSM in cancer of the uterine cervix. J Nucl Med 2008; 49:1177-82. [PMID: 18552145 DOI: 10.2967/jnumed.108.051326] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED Tumor uptake of copper(II)-diacetyl-bis(N(4)-methylthiosemicarbazone) (copper-ATSM), a hypoxia-targeting radiopharmaceutical, assessed by PET has been found to correlate with prognosis in several human cancers. Wide clinical utility of this tracer will require its labeling with a copper radionuclide having a longer half-life than the (60)Cu used in studies to date. The purpose of this work was to obtain the requisite preclinical data for copper-ATSM to file an investigational new drug application, followed by a crossover comparison of PET image quality and tumor uptake with (60)Cu-ATSM and (64)Cu-ATSM in women with cancer of the uterine cervix. METHODS The preclinical toxicology and pharmacology of a copper-ATSM formulation was examined using standard in vitro and in vivo assays, as well as 14-d toxicity studies in both rats and rabbits. For the clinical test-retest imaging study, 10 patients with cervical carcinoma underwent PET on separate days with (60)Cu-ATSM and (64)Cu-ATSM. Image quality was assessed qualitatively, and the tumor-to-muscle activity ratio was measured for each tracer. RESULTS The toxicology and pharmacology data demonstrated that the formulation has an appropriate margin of safety for clinical use. In the patient study, we found that the image quality with (64)Cu-ATSM was better than that with (60)Cu-ATSM because of lower noise. In addition, we found that the pattern and magnitude of tumor uptake of (60)Cu-ATSM and (64)Cu-ATSM on studies separated by 1-9 d were similar. CONCLUSION (64)Cu-ATSM appears to be a safe radiopharmaceutical that can be used to obtain high-quality images of tumor hypoxia in human cancers.
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Affiliation(s)
- Jason S Lewis
- Division of Radiological Sciences, Mallinckrodt Institute of Radiology, St. Louis, Missouri, USA.
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ARRONAX, a high-energy and high-intensity cyclotron for nuclear medicine. Eur J Nucl Med Mol Imaging 2008; 35:1377-87. [PMID: 18465127 DOI: 10.1007/s00259-008-0802-5] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Accepted: 03/27/2008] [Indexed: 10/22/2022]
Abstract
PURPOSE This study was aimed at establishing a list of radionuclides of interest for nuclear medicine that can be produced in a high-intensity and high-energy cyclotron. METHODS We have considered both therapeutic and positron emission tomography radionuclides that can be produced using a high-energy and a high-intensity cyclotron such as ARRONAX, which will be operating in Nantes (France) by the end of 2008. Novel radionuclides or radionuclides of current limited availability have been selected according to the following criteria: emission of positrons, low-energy beta or alpha particles, stable or short half-life daughters, half-life between 3 h and 10 days or generator-produced, favourable dosimetry, production from stable isotopes with reasonable cross sections. RESULTS Three radionuclides appear well suited to targeted radionuclide therapy using beta ((67)Cu, (47)Sc) or alpha ((211)At) particles. Positron emitters allowing dosimetry studies prior to radionuclide therapy ((64)Cu, (124)I, (44)Sc), or that can be generator-produced ((82)Rb, (68)Ga) or providing the opportunity of a new imaging modality ((44)Sc) are considered to have a great interest at short term whereas (86)Y, (52)Fe, (55)Co, (76)Br or (89)Zr are considered to have a potential interest at middle term. CONCLUSIONS Several radionuclides not currently used in routine nuclear medicine or not available in sufficient amount for clinical research have been selected for future production. High-energy, high-intensity cyclotrons are necessary to produce some of the selected radionuclides and make possible future clinical developments in nuclear medicine. Associated with appropriate carriers, these radionuclides will respond to a maximum of unmet clinical needs.
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Jentzen W, Weise R, Kupferschläger J, Freudenberg L, Brandau W, Bares R, Burchert W, Bockisch A. Iodine-124 PET dosimetry in differentiated thyroid cancer: recovery coefficient in 2D and 3D modes for PET(/CT) systems. Eur J Nucl Med Mol Imaging 2007; 35:611-23. [DOI: 10.1007/s00259-007-0554-7] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Accepted: 07/25/2007] [Indexed: 11/28/2022]
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Bigott HM, Laforest R, Liu X, Ruangma A, Wuest F, Welch MJ. Advances in the production, processing and microPET image quality of technetium-94m. Nucl Med Biol 2007; 33:923-33. [PMID: 17045173 DOI: 10.1016/j.nucmedbio.2006.07.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Revised: 05/26/2006] [Accepted: 07/01/2006] [Indexed: 11/19/2022]
Abstract
This work involves the production, processing and imaging of the short-lived, rarely used positron emission tomography (PET) radionuclide technetium-94m (94mTc). Our procedures are an extension of methods reported in the literature and are detailed within. A key modification was the development of a single step that combines purification and concentration of an aqueous 94mTc-pertechnetate solution, which both reduces processing time and increases the final concentration of the solution. Additionally, a convenient method for the direct recovery of 94mTc into an organic solvent was developed, eliminating the solvent transfer step needed for organic syntheses using 94mTc. Each of these advances potentially extends the scope of syntheses possible with this short-lived radionuclide. To explore the imaging potential of 94mTc, we carried out phantom imaging studies on small-scale high-resolution PET scanners to estimate the limitations of detection associated with 94mTc and PET. Preliminary studies demonstrate that useful images can be obtained with modern image reconstruction algorithms when using a correction for the cascade gamma ray contamination.
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Affiliation(s)
- Heather M Bigott
- Department of Chemistry, University of Missouri-Columbia, Columbia, MO 65211, USA
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Abstract
BACKGROUND Impure positron emitters have physical characteristics that degrade image quality compared to conventional positron emitters like 18F. Two impure positron emitters with potentially interesting applications are 124I and 86Y. The degradation in image quality due to the imperfection of these isotopes is quantified for a human three-dimensional (3-D) positron emission tomography (PET) system. An acquisition protocol to obtain similar image quality as for 18F imaging is determined by Monte Carlo simulations. METHODS The effects of larger positron range, associated singles and the other decay modes on image quality are determined by extensive Monte Carlo simulations of the Allegro scanner. Spatial resolution was evaluated for both isotopes and compared to spatial resolution of 18F. The loss in sensitivity due to triple coincidences was determined as a function of the axial acceptance angle of the PET scanner. The performance of the scanner at low count rates was studied by determining the noise equivalent count (NEC) values for different upper energy thresholds. The image degrading effect of spurious coincidences is taken into account by adding another factor to the NEC calculation. This allowed the contribution of spurious coincidences to be minimized by using a setting for the appropriate energy window. For this optimal energy window the amount of spurious and scattered coincidences was quantified. Simulations of count rate performance were also done to determine the peak NEC and the activity at which the maximum occurred. RESULTS Spatial resolution degradation, compared to 18F, is about 0.5 mm for 86Y and 1 mm for 124I. Associated singles have a similar effect as scattered coincidences, as they also add a background to the image. The effect, however, is less important than the effect of scatter. The fraction of triple coincidences is quite small for a 3-D PET scanner used for humans as the axial acceptance angle is still moderate. For the Allegro with an energy resolution of 18% the optimal upper energy threshold was determined at 600 keV. For 124I this leads to 2.5% extra contamination that needs to be added to the scatter fraction. For 86Y this fraction is about 5.5%. CONCLUSION 3-D PET images of 124I and 86Y have lower spatial resolution. For PET scanners used for humans the difference is not as important as for scanners used for animals. The limited positron decay fraction of both isotopes can be compensated by increasing the imaging time by a factor of 3-5 (same activity). A short coincidence window limits the contamination from other decay modes. Good energy resolution allows setting a selective upper energy threshold to limit the effect of spurious coincidences. With an appropriate setting of the energy window it should be possible to obtain good image quality in a relatively short time because of the high sensitivity of 3-D PET scanners.
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Sandström M, Tolmachev V, Kairemo K, Lundqvist H, Lubberink M. Performance of coincidence imaging with long-lived positron emitters as an alternative to dedicated PET and SPECT. Phys Med Biol 2005; 49:5419-32. [PMID: 15724533 DOI: 10.1088/0031-9155/49/24/002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
An important application of quantitative imaging in nuclear medicine is the estimation of absorbed doses in radionuclide therapy. Depending on the radionuclide used for therapy, quantitative imaging of the kinetics of the therapeutic radiopharmaceutical could be done using planar imaging, SPECT or PET. Since many nuclear medicine departments have a gamma camera system that is also suitable for coincidence imaging, the performance of these systems with respect to quantitative imaging of PET isotopes that could be of use in radionuclide dosimetry is of interest. We investigated the performance of a gamma camera with coincidence imaging capabilities with 99mTc, 111In, 18F and 76Br and a dedicated PET system with 18F and 76Br, using a single standard set of phantom measurements. Here, 76Br was taken as a typical example of prompt gamma-emitting PET isotopes that are applicable in radionuclide therapy dosimetry such as 86Y and 124I. Image quality measurements show comparable image contrasts for 76Br coincidence imaging and 111In SPECT. Although the spatial resolution of coincidence imaging is better than single photon imaging, the contrast obtained with 76Br is not better than that with 99mTc or 111In because of the prompt gamma involved. Additional improvements are necessary to allow for quantitative coincidence imaging of long-lived, prompt gamma producing positron emitters.
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Affiliation(s)
- Mattias Sandström
- Department of Hospital Physics, Uppsala University Hospital, 751 85 Uppsala, Sweden.
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Robinson S, Julyan PJ, Hastings DL, Zweit J. Performance of a block detector PET scanner in imaging non-pure positron emitters—modelling and experimental validation with 124I. Phys Med Biol 2004; 49:5505-28. [PMID: 15724539 DOI: 10.1088/0031-9155/49/24/008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The key performance measures of resolution, count rate, sensitivity and scatter fraction are predicted for a dedicated BGO block detector patient PET scanner (GE Advance) in 2D mode for imaging with the non-pure positron-emitting radionuclides 124I, 55Co, 61Cu, 62Cu, 64Cu and 76Br. Model calculations including parameters of the scanner, decay characteristics of the radionuclides and measured parameters in imaging the pure positron-emitter 18F are used to predict performance according to the National Electrical Manufacturers Association (NEMA) NU 2-1994 criteria. Predictions are tested with measurements made using 124I and show that, in comparison with 18F, resolution degrades by 1.2 mm radially and tangentially throughout the field-of-view (prediction: 1.2 mm), count-rate performance reduces considerably and in close accordance with calculations, sensitivity decreases to 23.4% of that with 18F (prediction: 22.9%) and measured scatter fraction increases from 10.0% to 14.5% (prediction: 14.7%). Model predictions are expected to be equally accurate for other radionuclides and may be extended to similar scanners. Although performance is worse with 124I than 18F, imaging is not precluded in 2D mode. The viability of 124I imaging and performance in a clinical context compared with 18F is illustrated with images of a patient with recurrent thyroid cancer acquired using both [124I]-sodium iodide and [18F]-2-fluoro-2-deoxyglucose.
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Affiliation(s)
- S Robinson
- North Western Medical Physics, Christie Hospital, Manchester, M20 4BX, UK
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Kull T, Ruckgaber J, Weller R, Reske S, Glatting G. Quantitative Imaging Of Yttrium-86 Pet with the Ecat Exact Hr+ In 2D Mode. Cancer Biother Radiopharm 2004; 19:482-90. [PMID: 15453963 DOI: 10.1089/cbr.2004.19.482] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The radionuclide 86Y potentially allows for the precise assessment of tissue radioactivity biodistribution and, thus, extrapolation of a therapeutic dose of 90Y-labeled compounds. A method to obtain quantitative images from 86Y-PET measurements after a background correction and a recalibration is presented. Cylinder and body phantom measurements with 18 F and 86Y using an ECAT EXACT HR+ tomograph were performed in 2D mode. A second-order series expansion is used to correct for the background of spurious coincidences in the sinogram. A recalibration of the positron emission tomography (PET) system, depending on the ratio of true coincidences and singles, is implemented. The correction for the nonannihilation coincidences with a second-order series expansion significantly improves the accuracy of quantitation: The lesion-to-background ratio is reproduced, and the variation of the activity concentration in the homogeneous background regions of the phantoms is smaller than 5%. The apparent activities in cold inserts of various densities is reduced to less than 15% of the concentration in the active region. The recalibration of the system works with a relative error of 0.2% +/- 2.4%. In conclusion, the used approximations lead to improved uniformity and quantitative accuracy in 86Y-PET measurements with the ECAT EXACT HR+.
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Affiliation(s)
- Thomas Kull
- Abteilung Nuklearmedizin, Universität Ulm, D-89070 Ulm, Germany
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