Diagnostic value of 18F-prostate specific membrane antigen PET/CT combined with multiparametric-MRI in identifying the grade group of prostate cancer / 中华泌尿外科杂志

ABSTRACT

Objective:To investigate the diagnostic value of the combination of 18F-prostate specific membrane antigen (PSMA) PET/CT and multiparametric magnetic resonance imaging (mpMRI) in identifying the grade group of prostate cancer, using parameters derived from the two imaging modalities. Method:Prostate cancer patients diagnosed by histopathology and received 18F-PSMA PET/CT and mpMRI during September 2018 to May 2021 in our hospital were retrospectively studied. The median age was 68(64-75), with the median PSA level of 14.74(7.75-24.19)ng/mL. All patients received mpMRI before biopsy. On biopsy, 6(12.2%) patients had International Society of Urological Pathology grade group(ISUP GG) 1 diseases, 16(32.7%) had ISUP GG 2 diseases, 12(24.5%) had ISUP GG 3 diseases, and 15(10.9%) had ISUP GG 4 or 5 diseases. Patients were then divided into high-grade group (ISUP 4-5) and low-grade group(ISUP 1-3). The median age of patients in high-grade group and low-grade group were 65(62-76) and 71(65-74), respectively. The PSA level in high-grade group and low-grade group were 15.11(6.63-42.86) ng/ml and 12.31(7.94-18.25) ng/ml, respectively. No significant differences were found in age and PSA level between the two groups ( P=0.334, P=0.448). All patients underwent 18F-PSMA PET/CT within 4 weeks after biopsy. The maximum standardized uptake value(SUV max) and the minimum apparent diffusion coefficient(ADC min)were recorded, and the ratio of SUV max/ ADC minwere calculated. The correlation between the above parameters and ISUP grade group were analyzed.The diagnostic value of the parameters was evaluated by the receiver operating characteristic (ROC) curve. Results:The data of 49 patients were analyzed. The average ADC minwas (0.57±0.16)×10 -3 mm 2/s, with the average SUV max and SUV max/ADC min of 15.30±12.54 and (29.69±23.72)×10 3, respectively. Statistical differences were found in SUV max ( P=0.012) and SUV max/ADC min ( P=0.002) between the high- and low-grade groups, while ADC min ( P=0.411) showed no statistical differences between the two groups. Significant positive correlations were found between SUV max(r=0.501, P<0.001), SUV max/ADC min (r=0.527, P<0.001) and ISUP grade group, respectively. There was a negative correlation between ADC min and ISUP grade group (r=-0.296, P=0.039). SUV max/ADC min was the best index to distinguish high-grade group from low-grade group prostate cancer with the area under the curve(AUC) of 0.749. In contrast, the AUC of SUV maxand ADC min were 0.731 and 0.615, respectively. The diagnostic sensitivity and specificity of SUV max/ADC min were 73.3% and 85.3%, respectively, with a critical value of 37.23×10 3. Conclusion:The combination use of 18F-PSMA PET/CT and mpMRI could improve the diagnostic efficiency for prostate cancer, compared to either modality alone. The ratio of SUV max/ADC min has a positive correlation with ISUP grade group, and is a promising index for distinguishing the high-grade prostate cancer from low-grade cancer.