One-Stop-Shop Whole-Body 68Ga-PSMA-11 PET/MRI Compared with Clinical Nomograms for Preoperative T and N Staging of High-Risk Prostate Cancer

Diagnostic performance of 68Ga-PSMA PET/CT in the detection of prostate cancer prior to initial biopsy: comparison with cancer-predicting nomograms

PURPOSE

To assess the diagnostic performance of ⁶⁸Ga-PSMA PET/CT for detecting suspected prostate cancer (PCa) and to compare it with that of two cancer-predicting nomograms.

METHODS

We performed a retrospective analysis of 146 consecutive patients with suspected PCa based on symptoms or elevated total prostate-specific antigen (tPSA) levels who underwent ⁶⁸Ga-PSMA PET/CT and histopathologic examinations from April 2017 to April 2018 in a large tertiary care hospital in China. The ⁶⁸Ga-PSMA PET/CT results (PCa or benignancy) were evaluated by two experienced nuclear medicine specialists. The risk of positive PCa was evaluated using ERSPC and PCPT nomograms. The diagnostic performances of ⁶⁸Ga-PSMA PET/CT and that of the two nomograms were compared via receiver operating characteristic (ROC) curve analysis, decision curve analysis, and logistic regression.

RESULTS

A total of 58 patients with tPSA of 0.4-50 ng/ml were included in the final analysis; PCa diagnosis was confirmed in 37 patients and excluded in 21 patients. ROC analysis showed that the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of ⁶⁸Ga-PSMA PET/CT were 91.67, 81.82, 89.19, and 85.71%, respectively, in per-patient analyses. ⁶⁸Ga-PSMA PET/CT exhibited a higher AUC (0.867) than those of ERSPC-RC3 (0.855) and PCPT-RC (0.770). The net benefit of ⁶⁸Ga-PSMA PET/CT was greatest for patients within threshold probabilities of 15-90%. Among the 58 patients, 11 (19%) biopsies suggested by ERSPC-RC3 were unnecessary and could have been avoided if judged by the ⁶⁸Ga-PSMA PET/CT results. Multivariate analysis revealed that the maximum standardised uptake value (SUV_max) and prostate volume were significant predictive factors for positive PCa results.

CONCLUSION

In suspected PCa patients with tPSA of 0.4-50 ng/ml, ⁶⁸Ga-PSMA PET/CT outperformed the nomograms in predicting cancer and reducing unnecessary biopsies. In addition, the risk of PCa was positively correlated with a higher SUV_max and lower prostate volume, which could help clinicians in making preliminary estimates of individual cancer risk, monitoring ⁶⁸Ga-PSMA PET/CT false-positive results and making biopsy decisions in daily medical practice.

Multimodal imaging for radiation therapy planning in patients with primary prostate cancer

Implementation of advanced imaging techniques like multiparametric magnetic resonance imaging (mpMRI) or Positron Emission Tomography (PET) in radiation therapy (RT) planning of patients with primary prostate cancer demands several preconditions: accurate staging of the extraprostatic and intraprostatic tumor mass, robust delineation of the intraprostatic gross tumor volume (GTV) and a reproducible characterization of the prostate cancer's biological properties. In the current review we searched for the currently available imaging techniques and we discussed their ability to fulfill these preconditions. We found that current pretreatment imaging was mainly performed with mpMRI and/or Prostate-specific membrane antigen PET imaging. Both techniques offered an accurate detection of the extraprostatic and intraprostatic tumor burden and had a major impact on RT concepts. However, some studies postulated that mpMRI and PSMA PET had complementary information for intraprostatic GTV detection. Moreover, interobserver differences for intraprostatic tumor delineation based on mpMRI were observed. It is currently unclear whether PET based GTV delineation underlies also interobserver heterogeneity. Further research is warranted to answer whether multimodal imaging is able to visualize biological processes related to prostate cancer pathophysiology and radiation resistance.

[Imaging in individualized uro-oncology]

The recent introduction of new diagnostic techniques has revolutionized uro-oncolgy. In addition to multiparametric magnetic resonance imaging (mpMRI), prostate-specific membrane antigen positron-emission tomography (PSMA-PET) plays an increasingly import role in daily practice. The introduction of three-dimensional (3D) printing technologies in the context of robot-assisted uro-oncological surgery represents a first step towards individualized 3D imaging. In the era of immunotherapy, imaging is challenged by new diagnostic criteria (iRECIST) and immune-related adverse effects.