Bone is the most common site of distant metastatic spread in prostate adenocarcinoma. Prostatespecific membrane antigen uptake has been described in both benign and malignant bone lesions, which can lead to false-positive findings on 68 Ga-prostate-specific membrane antigen-11 positron emission tomography (68 Ga-PSMA-11 PET). The purpose of this study was to evaluate the diagnostic accuracy of 68 Ga-PSMA-11 PET for osseous prostate cancer metastases and improve bone uptake interpretation using semi-quantitative metrics. METHODS. 56 prostate cancer patients (18 pre-prostatectomy, 38 biochemical recurrence) who underwent 68 Ga-PSMA-11 PET/MRI or PET/CT examinations with osseous PSMA-ligand uptake were included in the study. Medical records were reviewed retrospectively by boardcertified nuclear radiologists to determine true or false positivity based on a composite endpoint. For each avid osseous lesion, biological volume, size, PSMA-RADS rating, maximum standardized uptake value (SUVmax), and ratio of lesion SUVmax to liver, blood pool, and background bone SUVmax were measured. Differences between benign and malignant lesions were evaluated for statistical significance, and cutoff values for these parameters were determined to maximize diagnostic accuracy. RESULTS. Among 56 participants, 13 patients (22.8%) had false-positive osseous 68 Ga-PSMA-11 findings and 43 patients (76.8%) had true-positive osseous 68 Ga-PSMA-11 findings. Twentytwo patients (39%) had 1 osseous lesion, 18 (32%) had 2-4 lesions, and 16 (29%) had 5 or more lesions. Cutoff values resulting in statistically significant (p<0.005) differences between benign and malignant lesions were: PSMA-RADS ≥4, SUVmax ≥4.1, SUVmax ratio of lesion to blood by on November 1, 2020. For personal use only. jnm.snmjournals.org Downloaded from pool ≥2.11, to liver ≥0.55, and to bone ≥4.4. These measurements corresponded to lesion-based 68 Ga-PSMA-11 PET lesion detection rate for malignancy of 80%, 93%, 89%, 21%, 89%, and a specificity of 73%, 73%, 73%, 93%, 60%, respectively. CONCLUSION. PSMA-RADS rating, SUVmax, and SUVmax ratio of lesion to blood pool can help differentiate benign from malignant lesions on 68 Ga-PSMA-11 PET. SUVmax ratio to blood pool above 2.2 is a reasonable parameter to support image interpretation and presented superior lesion detection rate and specificity when compared to visual interpretation by PSMA RADS. These parameters hold clinical value by improving diagnostic accuracy for metastatic prostate cancer on 68 Ga-PSMA-11 PET/MRI and PET/CT.

No abstract

Highlights Combined topical permethrin plus oral ivermectin treats common scabies Patients 55 years or older may be more likely to experience post-scabetic itch Post-scabetic itch may persist for a median of 52.5 days (interquartile range, 28-135)

No abstract