Improving diagnostic efficacy of primary prostate cancer with combined (99m)Tc-PSMA SPECT/CT and multiparametric-MRI and quantitative parameters

PURPOSE: This prospective study aimed to evaluate the difference between (99m)Tc-PSMA single-photon emission computed tomography (SPECT)/CT and multiparametric magnetic resonance imaging (mpMRI) in the detection of primary prostate cancer (PCa). MATERIALS AND METHODS: Fifty-six men with suspected PCa between October 2019 and November 2022 were prospectively enrolled in this study. The median age of the patients was 70 years (range, 29-87 years). Patients were divided into high-(Gleason score>7, n=31), medium- (Gleason score=7, n=6) and low-risk groups (Gleason score < 7, n=6). All patients underwent (99m)Tc-PSMA SPECT/CT and mpMRI at an average interval of 3 days (range, 1-7 days). The maximum standardized uptake value (SUV(max)), the minimum apparent diffusion coefficient (ADC(min)), and their ratio (SUV(max)/ADC(min)) were used as imaging parameters to distinguish benign from malignant prostatic lesions. RESULTS: Of the 56 patients, 12 were pathologically diagnosed with a benign disease, and 44 were diagnosed with PCa. (99m)Tc-PSMA SPECT/CT and mpMRI showed no significant difference in the detection of primary PCa (kappa =0.401, P=0.002), with sensitivities of 97.7% (43/44) and 90.9% (40/44), specificities of 75.0% (9/12) and 75.0% (9/12), and AUC of 97.4% and 95.1%, respectively. The AUC of SUV(max)/ADC(min) was better than those of SUV(max) or ADC(min) alone. When SUV(max)/ADC(min) in the prostatic lesion was >7.0×10(3), the lesion was more likely to be malignant. When SUV(max)/ADC(min) in the prostatic lesion is >27.0×10(3), the PCa patient may have lymph node and bone metastases. SUV(max) was positively correlated with the Gleason score (r=0.61, P=0.008), whereas ADC(min) was negatively correlated with the Gleason score (r=-0.35, P=0.023). SUV(max)/ADC(min) was positively correlated with the Gleason score (r=0.59, P=0.023). SUV(max)/ADC(min) was the main predictor of the high-risk group, with an optimal cut-off value of 15.0×10(3). CONCLUSIONS: The combination of (99m)Tc-PSMA SPECT/CT and mpMRI can improve the diagnostic efficacy for PCa compared with either modality alone; SUV(max)/ADC(min) is a valuable differential diagnostic imaging parameter.