Journal of nuclear medicine : official publication, Society of Nuclear Medicine
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The aim was to compare the prostate-specific membrane antigen (PSMA)-targeting characteristics of PSMA-11, radiolabeled on the basis of chelation of 18F-AlF, with those of 68Ga-PSMA-11 to image PSMA-expressing xenografts. Methods: Labeling of 18F-AlF-PSMA-11 via 18F-AlF-complexation was performed as described by Boschi et al. and Malik et al. with minor modifications. Several conditions for the quality control of the labeling of 18F-AlF-PSMA-11 via 18F-AlF-complexation were evaluated to characterize the influence of ethanol, acetonitrile, and trifluoroacetic acid on the stability of the labeled product. ⋯ Conclusion:18F-AlF-PSMA-11 using direct labeling with aluminum fluoride can be produced in NH4OAc, pH 6.9; shows a high internalization rate; and visualizes PSMA-expressing tumors with similar tumor uptake. Lower kidney uptake than with 68Ga-PSMA-11 may be advantageous for tumor detection. However, the limited instability and consequent Al18F uptake in bone might hamper the visualization of small PCa bone metastases.
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Multicenter Study Comparative Study Clinical Trial
Prospective, Multisite, International Comparison of 18F-Fluoromethylcholine PET/CT, Multiparametric MRI, and 68Ga-HBED-CC PSMA-11 PET/CT in Men with High-Risk Features and Biochemical Failure After Radical Prostatectomy: Clinical Performance and Patient Outcomes.
A significant proportion of men with rising prostate-specific antigen (PSA) levels after radical prostatectomy (RP) fail prostate fossa (PF) salvage radiation treatment (SRT). This study was done to assess the ability of 18F-fluoromethylcholine (18F-FCH) PET/CT (hereafter referred to as 18F-FCH), 68Ga-HBED-CC PSMA-11 PET/CT (hereafter referred to as PSMA), and pelvic multiparametric MRI (hereafter referred to as pelvic MRI) to identify men who will best benefit from SRT. Methods: Prospective, multisite imaging studies were carried out in men who had rising PSA levels after RP, high-risk features, and negative/equivocal conventional imaging results and who were being considered for SRT. 18F-FCH (91/91), pelvic MRI (88/91), and PSMA (31/91) (Australia) were all performed within 2 wk. ⋯ Men with negative imaging results (MRI, 18F-FCH, or PSMA) had high (78%) SRT response rates. Conclusion:18F-FCH and PSMA had high detection rates for extra-PF disease in men with negative/equivocal conventional imaging results and rising PSA levels after RP. These findings affected management and treatment responses, suggesting an important role for PET in triaging men being considered for curative SRT.
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Radiomics analysis of 18F-FDG PET/CT images promises well for an improved in vivo disease characterization. To date, several studies have reported significant variations in textural features due to differences in patient preparation, imaging protocols, lesion delineation, and feature extraction. Our objective was to study variations in features before a radiomics analysis of 18F-FDG PET data and to identify those feature extraction and imaging protocol parameters that minimize radiomic feature variations across PET imaging systems. ⋯ Conclusion: Our results provide guidance to selecting optimized features from 18F-FDG PET/CT studies. We were able to demonstrate that feature variations can be minimized for selected image parameters and imaging systems. These results can help imaging specialists and feature engineers in increasing the quality of future radiomics studies involving PET/CT.
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Prostate-specific membrane antigen (PSMA)-targeted PET imaging has become commonly used in patients with prostate cancer (PCa). The PSMA reporting and data system version 1.0 (PSMA-RADS version 1.0) categorizes lesions on the basis of the likelihood of PCa involvement, with PSMA-RADS-3A (soft-tissue) and PSMA-RADS-3B (bone) lesions being indeterminate for the presence of disease. We retrospectively reviewed the imaging follow-up of such lesions to determine the rate at which they underwent changes suggestive of underlying PCa. ⋯ The presence of additional definitive sites of PCa (PSMA-RADS-4 and PSMA-RADS-5) increases the likelihood that indeterminate lesions will manifest as true-positive on follow-up imaging. Conclusion: PSMA-RADS-3A and PSMA-RADS-3B lesions are truly indeterminate in that proportions of findings in both categories demonstrate evidence of malignancy on follow-up imaging. Overall, PSMA-RADS-3A lesions are more likely than PSMA-RADS-3B lesions to represent sites of PCa, and this information should be considered when guiding patient therapy.
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177Lu-prostate-specific membrane antigen (PSMA)-617 enables targeted delivery of β-particle radiation to prostate cancer. We determined its radiation dosimetry and relationships to pretherapeutic imaging and outcomes. Methods: Thirty patients with prostate cancer receiving 177Lu-PSMA-617 within a prospective clinical trial (ACTRN12615000912583) were studied. ⋯ Significant correlations between aspects of screening 68Ga-PET/CT and tumor and normal tissue dose were observed, providing a rationale for patient-specific dosing. Reduced salivary and kidney doses were observed in patients with a higher tumor burden. The parotid dose also reduced with increasing body mass and body surface area.