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Purpose: To evaluate the performance of [ 68 Ga]Ga-PSMA-11 PET/CT in the diagnosis of recurrent prostate cancer (PC) after prostatectomy in a large multicentre cohort., Methods: The centres, which contributed to this study, were the departments of nuclear medicine of Heidelberg (Germany), Technical University of Munich (Germany) and Albert Einstein Hospital of São Paulo (Brazil). A total of 2533 patients who were scanned with [ 68 Ga]Ga-PSMA-11 PET/CT at 1 h p.i. due to recurrent PC after prostatectomy were included in this retrospective analysis. Exclusion criteria were as follows: patients with untreated primary tumour, previous chemotherapy or Xofigo®; those previously treated with exclusively external beam radiation therapy or HIFU; those referred for PSMA-therapy; and those treated with ADT (including first- and second-generation ADT) within the last 6 months. Potential influences of different factors such as PSA level, PSA doubling-time (PSA DT ), PSA velocity (PSA Vel ), Gleason Score (GSC, including the separate analysis of 7a and 7b), age and amount of injected tracer were evaluated in a multivariable analysis., Results: The rate of pathologic PET/CT-scans was 43% for PSA ≤ 0.2 ng/ml, 58% for PSA > 0.2 to ≤ 0.5, 72% for PSA > 0.5 to ≤ 1.0 and increased to a maximum of 93% for PSA > 10 ng/ml. A pathological PET/CT was significantly (p = 0.001) associated with PSA level and higher GSC. Amount of injected tracer, age, PSA DT and PSA Vel were not associated with a higher probability of a pathological scan., Conclusion: [ 68 Ga]Ga-PSMA-11 PET/CT at 1 h p.i. confirmed its high performance in the largest patient cohort yet analysed. Tumour detection showed a clear association with higher PSA and higher GSC. No association was found between a pathological [ 68 Ga]Ga-PSMA-11 PET/CT and age, amount of injected tracer, PSA DT or PSA Vel .

We report a case of a 43-year-old man who underwent a radical prostatectomy 3 years before the procedure (June 2015) for a locally advanced Gleason 7(4 + 3) prostate adenocarcinoma (pT3aN0), with negative surgical margins, followed by salvage radiotherapy. He also underwent antiandrogen therapy for biochemical relapse (bicalutamide) from October 2016 through May 2017, but prostate-specific antigen continued to rise (2.5 ng/mL [December 2017] and 3.3 ng/mL [February 2018]). At this point, he underwent a Ga-prostate-specific membrane antigen PET/CT, and after multidisciplinary discussion, the therapeutic option chosen was image-guided salvage cryoablation.

Objective: Positron emission tomography in association with magnetic resonance imaging (PET/MR) and 68 Ga-PSMA-11 has shown superior detection in recurrent prostate cancer patients as compared to PET/computed tomography (PET/CT). There are, however, several technological differences between PET/CT and PET/MR systems which affect the PET image quality. The objective of this study was to assess the reproducibility of PET/CT and PET/MR SUV's in recurrent prostate cancer patients. We randomized the patients regarding the order of the PET/CT and PET/MR scans to reduce the influence of tracer uptake as a function of time., Methods: Thirty patients, all with biochemical recurrence after radical prostatectomy, underwent whole-body PET/CT and PET/MR scans after intravenous injection of a single dose of 68 Ga-PSMA-11. Fifteen patients underwent PET/CT first and 15 patients underwent PET/MR first. Volumes of interest on tumor lesions were outlined and maximum standardized uptake value (SUVmax) corrected for lean body mass was calculated. Correlation and agreement between scans were assessed by generalized linear mixed-effects models and Bland-Altman analysis. The association between SUV, patient characteristics and imaging parameters was assessed., Results: Eighteen of the 30 evaluated patients had at least one positive lesion, giving an overall detection rate of 60%. In total, there were 34 visible lesions: 5 local recurrences, 22 lymph node metastases and 7 bone metastases. One group acquired PET/CT and PET/MR at median time points of 63.0 and 159.0 min, while the other group acquired PET/MR and PET/CT at median time points of 92.0 and 149.0 min. SUVmax between scans was linearly correlated, described by the equation Y(PET/CT SUVmax) = 0.75 + 1.00 × (PET/MR SUVmax), on average 20% higher on PET/CT than on PET/MR. SUV associated significantly only with type of lesion, scan time post-injection and acquisition time per bed position., Conclusions: SUVmax from PET/CT and PET/MR are linearly correlated, on average 20% higher on PET/CT than on PET/MR and should, therefore, not be used interchangeably in patient follow-up.

Purpose: Since the introduction of 68 Ga-PSMA-11 PET/CT for imaging prostate cancer (PC) we have frequently observed mediastinal lymph nodes (LN) showing tracer uptake despite being classified as benign. The aim of this evaluation was to further analyze such LN., Methods: Two patient groups with biphasic 68 Ga-PSMA-11 PET/CT at 1 h and 3 h p.i. were included in this retrospective evaluation. Group A (n = 38) included patients without LN metastases, and group B (n = 43) patients with LN metastases of PC. SUV of mediastinal/paraaortal LN of group A (n = 100) were compared to SUV of LN metastases of group B (n = 91). Additionally, 22 randomly selected mediastinal and paraaortal LN of patients without PC were immunohistochemically (IHC) analyzed for PSMA expression., Results: In group A, 7/38 patients (18.4%) presented with at least one PSMA-positive mediastinal LN at 1 h p.i. and 3/38 (7.9%) positive LN at 3 h p.i. with a SUVmax of 2.3 ± 0.7 at 1 h p.i. (2.0 ± 0.7 at 3 h p.i.). A total of 11 PSMA-positive mediastinal/paraaortal LN were detected in nine patients considering both imaging timing points. SUVmax of LN-metastases was 12.5 ± 13.2 at 1 h p.i. (15.8 ± 17.0 at 3 h p.i.). SUVmax increased clearly (> 10%) between 1 h and 3 h p.i. in 76.9% of the LN metastases, and decreased significantly in 72.7% of the mediastinal/paraaortal LN. By IHC, PSMA-expression was observed in intranodal vascular endothelia of all investigated LN groups and to differing degrees within germinal centers of 15/22 of them (68.1%). Expression was stronger in mediastinal nodes (p = 0.038) and when follicular hyperplasia was present (p = 0.050)., Conclusion: PSMA-positive mediastinal/paraaortal benign LN were visible in a notable proportion of patients. PSMA-positivity on the histopathological level was associated with the activation state of the LN. However, in contrast to LN metastases of PC, they presented with significantly lower uptake, which, in addition, usually decreased over time.