ABSTRACT
Objective:To explore the diagnostic value of 68Ga-prostate specific membrane antigen (PSMA)-11 PET/MR multiparameter multimodal functional imaging in the diagnosis of naive prostate cancer (PCa), and to analyze its efficacy in the early stages of PCa. Methods:From July to September 2019, 45 suspected or pathologically confirmed PCa patients (average age: 69 years) who met the inclusion criteria were collected to perform 68Ga-PSMA-11 PET/MR examination in Nanjing First Hospital. After the scanning was completed, the method of region of interest (ROI) was used to semi-quantitatively calculate the tumor radioactive uptake in the fusion image, including the maximum standardized uptake value (SUV max), tumor metabolic volume (MTV) and mean standardized uptake value (SUV mean), and PSMA expression load was calculated(SUV mean×MTV). Apparent diffusion coefficient (ADC) values of ROI were measured in ADC images ( b=1 500 s/mm 2). The efficacy of 68Ga-PSMA-11 PET/MR in the preoperative diagnosis of PCa and the effect on clinical staging were evaluated with the pathological results. The correlation between prostate specific antigen (PSA) and radiation uptake in PCa tissues, PSMA expression load and ADC values was analyzed by Pearson correlation. Independent-sample t test was used to analyze the data. Results:Pathologically, 38 of the 45 patients were with PCa and 7 patients had benign prostatic hypertrophy (BPH), and metastasis occurred in 12 of the 38 PCa patients. 68Ga-PSMA-11 PET/MR detected 39 cases of PCa with one of which was false-positive. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 68Ga-PSMA-11 PET/MR were 100%(38/38), 6/7, 97.4%(38/39), 6/6 and 97.8%(44/45), respectively. The tumor tissues of PCa often showed focal radioactive uptake, and the T 2 weighted imaging (WI) showed focal low signal and limited dispersion. BPH showed slightly uneven uptake, and T 2WI and diffusion weighted imaging (DWI) showed uneven diffuse signals. SUV max of PCa was significantly higher than that of BPH (24.66±19.21 vs 4.97±2.13; t=5.208, P<0.001). ADC values of PCa were significantly lower than that of BPH ((0.91±0.37)×10 -3vs (1.08±0.24)×10 -3 mm/s 2; t=2.816, P<0.05). SUV max and the expression loads of PSMA in PCa were positively correlated with PSA ( r values: 0.42 and 0.71, both P<0.05). ADC values of tumor tissues in PCa were negatively correlated with PSA ( r=-0.37, P=0.013). Conclusion:68Ga-PSMA-11 PET/MR has great merits in the early diagnosis and staging of PCa.