The role of PSMA PET/CT in distinguishing malignant from benign solitary bone lesions in prostate cancer patients.

[PURPOSE] This study evaluates the ability of prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) to distinguish between benign and malignant solitary bone lesions (SBLs) in prostate cancer (PCa) patients in correlation with standard imaging and clinical features.

[METHODS] 18F-piflufolastat and 68Ga-gozetotide PSMA PET/CT imaging reports of 1480 PCa patients from September 2021 to February 2023 were retrospectively reviewed. SBLs were classified as benign, malignant, or indeterminate based on imaging reports. Indeterminate SBLs were followed up over six months for reclassification. Comparative analyses, including Wilcoxon rank sum and chi-squared tests, assessed differences in standardized uptake values on PET, prostate-specific antigen (PSA) levels, and lesion locations.

[RESULTS] 208 of 1480 (14 %) PSMA PET/CT scans reported an SBL. 106/208 (51 %) SBLs were malignant, 56/208 (27 %) benign, and 46/208 (22 %) indeterminate. Compared to benign lesions, malignant SBLs had a significantly higher SUV [5.20 (2.86-11.13) vs. 2.21 (1.6-2.84); p < 0.001] and SUV/liver SUV [0.9 (0.51-2.31) vs. 0.44 (0.32-0.58); p < 0.001], although serum PSA levels were not significantly different. Malignant SBLs were most reported in pelvis (37/106, 35 %), while most benign SBLs were in ribs (31/56, 55 %). Presence or absence of non-osseous metastasis, and radiopharmaceutical type were not associated with significant differences in PSA, SUV, or the common locations of malignant or benign SBLs. Indeterminate SBLs were reclassified as benign in 20/46 (48 %) patients, most commonly in the ribs (19/46, 41 %).

[CONCLUSION] Location, SUV and SUV/liver SUV of SBL on PSMA PET/CT may help differentiate benign from malignant etiologies while considering other imaging and clinical features.