In prostate cancer with biochemical failure after therapy, current imaging techniques have a low detection rate at the prostate-specific antigen (PSA) levels at which targeted salvage therapy is effective. 11 C-choline and 18 F-fluoromethylcholine, though widely used, have poor sensitivity at low PSA levels. 68 Ga-PSMA (Glu-NH-CO-NH-Lys-(Ahx)-[ 68 Ga-N,N′-bis[2-hydroxy-5-(carboxyethyl) benzyl]ethylenediamine-N,N′-diacetic acid]) has shown promising results in retrospective trials. Our aim was to prospectively compare the detection rates of 68 Ga-PSMA versus 18 F-fluoromethylcholine PET/CT in men who were initially managed with radical prostatec-tomy, radiation treatment, or both and were being considered for targeted therapy. Methods: A sample of men with a rising PSA level after treatment, eligible for targeted treatment, was prospectively included. Patients on systemic treatment were excluded. 68 Ga-PSMA, 18 F-fluoromethylcholine PET/CT, and diagnostic CT were performed sequentially on all patients between January and April 2015, and the images were assessed by masked, experienced interpreters. The findings and their impact on management were documented, together with the results of histologic follow-up when feasible. Results: In total, 38 patients were enrolled. Of these, 34 (89%) had undergone radical prostatectomy and 4 (11%) had undergone radiation treatment. Twelve (32%) had undergone salvage radiation treatment after primary radical prostatectomy. The mean PSA level was 1.74 ± 2.54 ng/mL. The scan results were positive in 26 patients (68%) and negative with both tracers in 12 patients (32%). Of the 26 positive scans, 14 (54%) were positive with 68 Ga-PSMA alone, 11 (42%) with both 18 F-fluoromethylcholine and 68 Ga-PSMA, and only 1 (4%) with 18 F-fluoromethylcholine alone. When PSA was below 0.5 ng/mL, the detection rate was 50% for 68 Ga-PSMA versus 12.5% for 18 F-fluoromethylcholine. When PSA was 0.5-2.0 ng/mL, the detection rate was 69% for 68 Ga-PSMA versus 31% for 18 F-fluoromethylcholine, and when PSA was above 2.0, the detection rate was 86% for 68 Ga-PSMA versus 57% for 18 F-fluoromethylcholine. On lesion-based analysis , 68 Ga-PSMA detected more lesions than 18 F-fluoromethylcholine (59 vs. 29, P , 0.001). The tumor-to-background ratio in positive scans was higher for 68 Ga-PSMA than for 18 F-fluoromethylcholine (28.6 for 68 Ga-PSMA vs. 9.4 for 18 F-fluoromethylcholine, P , 0.001). There was a 63% (24/38 patients) management impact, with 54% (13/24 patients) being due to 68 Ga-PSMA imaging alone. His-tologic follow-up was available for 9 of 38 patients (24%), and 9 of 9 68 Ga-PSMA-positive lesions were consistent with prostate cancer (68 Ga-PSMA was true-positive). The lesion positive on 18 F-fluoromethylcholine imaging and negative on 68 Ga-PSMA imaging was shown at biopsy to be a false-positive 18 F-fluoromethylcholine finding (68 Ga-PSMA was true-negative). Conclusion: In patients with biochemical failure and a low PSA level, 68 Ga-PSMA demonstrated a significantly higher detection rate than ...

BACKGROUND Fluorodeoxyglucose (FDG) positron emission tomography (PET) has well-characterized limitations in prostate adenocarcinoma (PCA). However, data assessing the utility of PET in neuroendocrine prostate cancer (NEPC) is limited to isolated case reports. Herein, we describe the first case series to assess the utility of FDG-PET in NEPC. METHODS Inclusion criteria consisted of clinically progressive metastatic PCA in the setting of a chromogranin-A levels >1.5x the upper limit of normal, and ≥1 FDG-PET scan after the diagnosis of NEPC, which yielded 23 patients. All metastatic lesions on CT, PET, and bone scan were read by two independent physicians. RESULTS Five hundred ninety two unique lesions were identified across all imaging modalities, 510 were bone metastases, and 82 were soft tissue metastases. Of bone lesions, 22.2%, 92.7%, and 77.6% were detected by PET, CT, and bone scan, respectively. Of soft tissue lesions, 95.1% and 97.5% were detected by PET and CT, respectively. Stratified by the median survival from NEPC diagnosis, patients who survived <2.2 versus ≥2.2 years had more PET avid bone (8 vs. 2, P=0.06) and soft tissue lesions (7 vs. 1, P=0.01), and higher average SUVmax of bone (5.49 vs. 3.40, P=0.04) and soft tissue lesions (8.02 vs. 3.90, P=0.0002). CONCLUSIONS In patients with clinical NEPC, we demonstrate that FDG-PET has clinical utility in the detection of metastatic disease. In addition to detection, PET allows for treatment response to determine tumor viability. With novel therapies on the horizon to treat NEPC, consideration to investigate the use of FDG-PET to monitor response is warranted.

Purpose To compare morphological and functional MRI metrics and determine which ones perform best in assessing response to neoadjuvant chemoradiotherapy (CRT) in rectal cancer. Materials and methods This retrospective study included 24 uniformly-treated patients with biopsy-proven rectal adenocarcinoma who underwent MRI, including diffusion-weighted (DW) and dynamic contrast-enhanced (DCE) sequences, before and after completion of CRT. On all MRI exams, two experienced readers independently measured longest and perpendicular tumour diameters, tumour volume, tumour regression grade (TRG) and tumour signal intensity ratio on T2-weighted imaging, as well as tumour volume and apparent diffusion coefficient on DW-MRI and tumour volume and transfer constant Ktrans on DCE-MRI. These metrics were correlated with histopathological percent tumour regression in the resected specimen (%TR). Inter-reader agreement was assessed using the concordance correlation coefficient (CCC). Results For both readers, post-treatment DW-MRI and DCE-MRI volumetric tumour assessments were significantly associated with %TR; DCE-MRI volumetry showed better inter-reader agreement (CCC=0.700) than DW-MRI volumetry (CCC=0.292). For one reader, mrTRG, post-treatment T2 tumour volumetry and assessments of volume change made with T2, DW-MRI and DCE-MRI were also significantly associated with %TR. Conclusion Tumour volumetry on post-treatment DCE-MRI and DW-MRI correlated well with %TR, with DCE-MRI volumetry demonstrating better inter-reader agreement.

(18)F-FDG-PET/CT imaging should be performed as late as reasonably possible after tracer administration in order to increase tumour-to-background contrast and thereby improve the sensitivity of demonstrating additional sites of disease. Dual-time-point (18)FDG-PET/CT may be of benefit in the evaluation of intra-abdominal lesions but does not improve the overall evaluation of pulmonary lesions.

Introduction Accurate grading at the time of diagnosis is fundamental to risk stratification and treatment decision making, particularly for men being considered for Active Surveillance (AS). With the introduction of prostate-specific membrane antigen (PSMA) positron emission tomography (PET) there has been considerable improvement in sensitivity and specificity for the detection and staging of clinically significant prostate cancer. Our study aims to determine the role of PSMA PET/CT in men with newly diagnosed low or favourable intermediate risk prostate cancer to better select men for AS. Method This is a retrospective single centre study performed from January 2019 and October 2022. This study includes men identified from electronic medical record system who had undergone a PSMA PET/CT following newly diagnosed low or favourable-intermediate risk prostate cancer. Primary outcome was to assess the change in management for men being considered for AS following PSMA PET/CT results on the basis of PSMA PET characteristics. Results In total, there were 11 of 30 men (36.67%) who were assigned management by AS and 19 of 30 men (63.33%) who had definitive treatment. 15 of the 19 men that needed treatment had concerning features on PSMA PET/CT results. Of the 15 men with concerning features on PSMA PET, 9 (60%) men were found to have adverse pathological features on final prostatectomy features. Conclusion This retrospective study suggests that PSMA PET/CT has potential to influence the management of men with newly diagnosed prostate cancer that would otherwise be appropriate for active surveillance.