The association of quantitative PSMA PET parameters with pathologic ISUP grade: an international multicenter analysis.

PURPOSE: To assess if PSMA PET quantitative parameters are associated with pathologic ISUP grade group (GG) and upgrading/downgrading. METHODS: PCa patients undergoing radical prostatectomy with or without pelvic lymph node dissection staged with preoperative PSMA PET at seven referral centres worldwide were evaluated. PSMA PET parameters which included SUVmax, PSMAvolume, and total PSMA accumulation (PSMAtotal) were collected. Multivariable logistic regression evaluated the association between PSMA PET quantified parameters and surgical ISUP GG. Decision-tree analysis was performed to identify discriminative thresholds for all three parameters related to the five ISUP GGs The ROC-derived AUC was used to determine whether the inclusion of PSMA quantified parameters improved the ability of multivariable models to predict ISUP GG ≥ 4. RESULTS: A total of 605 patients were included. Overall, 2%, 37%, 37%, 10% and 13% patients had pathologic ISUP GG1, 2, 3, 4, and 5, respectively. At multivariable analyses, all three parameters SUVmax, PSMAvolume and PSMAtotal were associated with GG ≥ 4 at surgical pathology after accounting for PSA and clinical T stage based on DRE, hospital and radioligand (all p < 0.05). Addition of all three parameters significantly improved the discrimination of clinical models in predicting GG ≥ 4 from 68% (95%CI 63 - 74) to 74% (95%CI 69 - 79) for SUVmax, 72% (95%CI 67 - 76) for PSMAvolume, 74% (70 - 79) for PSMAtotal and 75% (95%CI 71 - 80) when all parameters were included (all p < 0.05). Decision-tree analysis resulted in thresholds that discriminate between GG (SUVmax 0-6.5, 6.5-15, 15-28, > 28, PSMAvol 0-2, 2-9, 9-20 and > 20 and PSMAtotal 0-12, 12-98 and > 98). PSMAvolume was significantly associated with GG upgrading (OR 1.03 95%CI 1.01 - 1.05). In patients with biopsy GG1-3, PSMAvolume ≥ 2 was significantly associated with higher odds for upgrading to ISUP GG ≥ 4, compared to PSMAvolume < 2 (OR 6.36, 95%CI 1.47 - 27.6). CONCLUSION: Quantitative PSMA PET parameters are associated with surgical ISUP GG and upgrading. We propose clinically relevant thresholds of these parameters which can improve in PCa risk stratification in daily clinical practice.

Lymph node staging with fluorine-18 prostate specific membrane antigen 1007-positron emission tomography/computed tomography in newly diagnosed intermediate- to high-risk prostate cancer using histopathological evaluation of extended pelvic node dissection as reference.

PURPOSE: Fluorine-18 (18F) prostate-specific membrane antigen (PSMA) 1007 (18F-PSMA-1007) is a radiotracer used in prostate cancer (PCa) staging. So far, no large histopathological validation study has been conducted. The objective was to determine diagnostic accuracy of 18F-PSMA-1007 PET/CT compared to histopathological results of extended pelvic lymph node dissection (ePLND) in men with intermediate- or high-risk PCa. METHODS: Men with newly confirmed intermediate- or high-risk PCa were prospectively enrolled in the Molecular Imaging 18F-PSMA-1007 PET/CT for lymph Node sTaging in primary PCa (MINT) trial. PET/CT images were read by two nuclear medicine physicians. Diagnostic accuracy was evaluated by histopathology of template resections. Sensitivity, specificity, and positive and negative predictive values (PPV, NPV) for LNI detection of 18F-PSMA-1007 PET/CT were calculated. RESULTS: Ninety-nine men were evaluated; 30.3% showed histologically confirmed LNI. Median number of resected nodes was 22 (IQR 17-28). Patient-based sensitivity, specificity, PPV, and NPV were 53.3% (95% CI 34.3-71.7%), 89.9% (95% CI 80.2-95.8%), 69.6% (95% CI 51.2-83.3%), and 81.6% (95% CI 75.0-86.8%), respectively. Template-based sensitivity was 12.9% (95% CI 5.7-23.9%), specificity 97.7% (95% CI 96.6-98.5%), PPV 23.5% (95% CI 12.7-39.5%), and NPV 95.3% (95% CI 94.9-95.7%). CONCLUSION: 18F-PSMA-1007 PET/CT showed high specificity but moderate to low sensitivity for LNI detection in intermediate- and high-risk PCa. It cannot replace ePLND for staging. Additional studies are needed to determine exact scan indications in lymph node staging for the primary diagnostic pathway in intermediate- or high-risk PCa. TRIAL REGISTRY: December 12, 2018, Netherlands Trial Registry, NTR7670 ( https://www.trialregister.nl/trial/7428 ).

The diagnostic hurdle of an elderly male with bone pain: how 18F-FDG-PET led to diagnosis of a leiomyosarcoma of the adrenal gland.

It is uncommon for patients to present with bone metastases while the primary tumor is still unknown. The case of a patient with bone metastases as primary presentation of leiomyosarcoma, who was diagnosed after a 18F-FDG PET-CT and a CT-guided biopsy of the adrenal gland is described. If after routine physical, laboratory and radiological investigations no diagnosis can be made, 18F-FDG PET should be added to the conventional work-up of patients with unknown primary cancer. In this way, unnecessary and enduring suffering of symptomatic patients may be prevented.