Diagnostic Accuracy Of ⁶⁸Ga-PSMA PET/CT Versus MpMRI For Pelvic Invasion In Patients With Prostate Cancer

Background:At present,patients with prostate cancer（PCa）in China are usually diagnosed with advanced stage,often accompanied by pelvic lymph node metastasis,seminal vesicle invasion,bone metastasis,bladder or rectal invasion and other pelvic invasion.The early diagnosis of PCa is still a clinical problem to be overcome.Traditional imaging examinations,such as Ultrasonography,CT and MRI,play an important role in PCa diagnosis and prognosis assessment,but there are still some deficiencies.mpMRI combines DEC-MRI,DWI,ADC and other technologies in MR functional imaging to further improve the accuracy of PCa diagnosis.The study found that ⁶⁸Ga-PSMA PET/CT played an important role in the early diagnosis of PCa due to its excellent diagnostic performance,which changed the traditional diagnostic model of PCa.Objective:To investigate the diagnostic value of ⁶⁸Ga-PSMA PET/CT and mpMRI in pelvic invasion of PCa.Materials and Methods:Clinical data of 118 patients diagnosed with prostate cancer was collected from May 2017 to December 2019,including age,BMI,prostate volume,serum PSA value,Gleason score and PI-RADS score,SUVmax value,pathology and lymph node of prostate pathological results,and the positive focal distribution in ⁶⁸Ga-PSMA PET/CT imaging and mpMRI imaging.The following studies were conducted:（1）analyzing the correlation between SUVmax value and PI-RADS score and Gleason score and serum PSA value;（2）According to postoperative pathological and imaging results,patients were divided into the pelvic invasion group and the non-invasion group.Comparing the differences between serum PSA value,Gleason score,SUVmax score and PI-RADS score.（3）H&E staining and PSMA immunohistochemical analysis were performed on the pathological tissues of patients with seminal vesicular and lymph node metastasis diagnosed by preoperative imaging to verify the sensitivity and specificity of⁶⁸Ga-PSMA PET/CT and mpMRI diagnosis,and to evaluate the diagnostic value of⁶⁸Ga-PSMA PET/CT and mpMRI in prostate cancer lesions,pelvic invasion and lymph node metastasis.Results:SUVmax value and PI-RADS score in PCa patients were positively correlated with serum PSA value and Gleason score.The serum PSA value,SUVmax value,PI-RADS score and Gleason scores of PCa patients with pelvic invasion were significantly higher than those without pelvic invasion.There were positive correlations among serum PSA value,SUVmax value,PI-RADS score and Gleason scores of 118 PCa patients（P<0.001）.The serum PSA value,SUVmax value,PI-RADS score and Gleason score of patients with pelvic invasion group were significantly higher than those without pelvic invasion group,and the differences were statistically significant（P<0.05）.The sensitivity,specificity,positive predictive value and negative predictive value of ⁶⁸Ga-PSMA PET/CT diagnosis of PCa were 95.56%,95.89%,93.48%and 97.22%,while the sensitivity,specificity,positive predictive value and negative predictive value of mpMRI diagnosis were 93.18%,93.24%,89.13%and 95.83%,respectively.Both of them have certain value in PCa pelvic invasion diagnosis,and there is no statistical difference.In 32 patients with pelvic lymph node metastasis,the number of patients and number of lymph nodes detected by ⁶⁸Ga-PSMA PET/CT in lymph nodes with diameter<5 mm,5-10 mm,and>10 mm were 1,6,25,and 1,14,and 45,respectively.The number of patients and lymph nodes detected by mpMRI were 0,4,22 and 0,10 and 38,respectively.There was no statistical difference in the diagnosis of pelvic lymph node metastasis between the two,but ⁶⁸Ga-PSMA PET/CT showed more advantages in the diagnosis of potential metastatic lesions of PCa.Conclusions:SUVmax value and PI-RADS score in PCa patients were positively correlated with serum PSA value and Gleason score.The serum PSA value,SUVmax value,PI-RADS score and Gleason scores of PCa patients with pelvic invasion were significantly higher than those without pelvic invasion.⁶⁸Ga-PSMA PET/CT and mpMRI showed high sensitivity and specificity in the diagnosis of PCa pelvic invasion,demonstrating great diagnostic value.Compared with mpMRI,68Ga-PSMA PET/CT has an advantage in detecting potential metastatic lesions of PCa.Preoperative ⁶⁸Ga-PSMA PET/CT has a certain guiding significance for regional lymph node dissection in patients with PCa,but it can not replace the diagnostic value of mpMRI in tumor location and stage assessment.