Added Value of [18F]PSMA‐1007 PET/CT and PET/MRI in Patients With Biochemically Recurrent Prostate Cancer: Impact on Detection Rates and Clinical Management

Background Prostate‐specific membrane antigen (PSMA) positron emission tomography (PET) can change management in a large fraction of patients with biochemically recurrent prostate cancer (BCR). Purpose To investigate the added value of PET to MRI and CT for this patient group, and to explore whether the choice of the PET paired modality (PET/MRI vs. PET/CT) impacts detection rates and clinical management. Study Type Retrospective. Subjects 41 patients with BCR (median age [range]: 68 [55–78]). Field Strength/Sequence 3T, including T1‐weighted gradient echo (GRE), T2‐weighted turbo spin echo (TSE) and dynamic contrast‐enhanced GRE sequences, diffusion‐weighted echo‐planar imaging, and a T1‐weighted TSE spine sequence. In addition to MRI, [ 18 F]PSMA‐1007 PET and low‐dose CT were acquired on the same day. Assessment Images were reported using a five‐point Likert scale by two teams each consisting of a radiologist and a nuclear medicine physician. The radiologist performed a reading using CT and MRI data and a joint reading between radiologist and nuclear medicine physician was performed using MRI, CT, and PET from either PET/MRI or PET/CT. Findings were presented to an oncologist to create intended treatment plans. Intrareader and interreader agreement analysis was performed. Statistical Tests McNemar test, Cohen's κ , and intraclass correlation coefficients. A P ‐value <0.05 was considered significant. Results 7 patients had positive findings on MRI and CT, 22 patients on joint reading with PET/CT, and 18 patients joint reading with PET/MRI. For overall positivity, interreader agreement was poor for MR and CT ( κ = 0.36) and almost perfect with addition of PET (PET/CT κ = 0.85, PET/MRI κ = 0.85). The addition of PET from PET/CT and PET/MRI changed intended treatment in 20 and 18 patients, respectively. Between joint readings, intended treatment was different for eight patients. Data Conclusion The addition of [ 18 F]PSMA‐1007 PET/MRI or PET/CT to MRI and CT may increase detection rates, could reduce interreader variability, and may change intended treatment in half of patients with BCR. Level of Evidence 3 Technical Efficacy Stage 3