| Background and AimedThe incidence of prostate cancer is increasing year by year,and improving its diagnostic efficiency is a key prerequisite for precise treatment.At present,MRI is the main imaging technique for detecting prostate cancer,but there are also problems such as gray area diagnosis and limited detection range.18F-FDG PET/CT has certain advantages in detecting the primary tumors and metastases of the whole body,but its sensitivity and specificity for diagnosing prostate cancer are poor.Recent studies have shown that a type of prostate-specific membrane antigen(PSMA)is specifically and highly expressed on the surface of prostate cancer cells.The principle that the small molecule inhibitor of PSMA labeled with radionuclide 18F can efficiently and specifically bind to its cell surface receptors has become a specific diagnostic target for primary and metastatic prostate cancer.It will solve traditional problems that MRI and 18F-FDG PET/CT faced,and greatly improve the diagnostic efficiency of prostate cancer.Based on this,this study compared the results of 18F-PSMA PET/CT and traditional imaging methods in the diagnosis of primary prostate cancer and metastases and explored the value of using 18F-PSMA PET/CT in the diagnosis of prostate cancer-related cases.Material and MethodologyA retrospective study of the imaging data of 32 prostate cancer patients who underwent 18F-PSMA PET/CT and MRI at Qilu Hospital of Shandong University from February 2018 to June 2020 and was confirmed by pathology.The imaging agent used was 18F labelled DCPFyL(2-(3-(1-carboxy-5-(6-[18F]fluoro-pyridine-3-carbonyl)-[amino]-pentyl)-ureido)-pentanedioic acid).The patients who underwent prostate MRI scan within 60 days before and after PET/CT examination and there is no treatment and puncture between the two inspections.Among the 32 male patients,the age range was 48-83 years,with an average age of 65.37 years;the serum tPSA range before PET/CT examination was 0.03-228.4 ng/mL,the average was 27.37ng/mL,and the Gleason score range was 6-10 points,the average 7.84 points.The images were evaluated visually,and two experienced radiologists and nuclear medicine physicians in a double-blind manner read the images.First,the radiologists assessed whether there are lesions in the prostate and other parts of the pelvis on the MRI image;Medical doctors visually evaluate whether there are abnormal imaging agent concentration foci in the same field of view as MRI on the PET/CT image.By defining the diagnostic criteria to determine the positive lesions on the two imaging methods,referring to the pathological results such as follow-up and needle biopsy,and according to the degree of certainty of the positive lesions by the image reader,the lesions are divided into three groups,group a(definitely no positive Lesion group),group b(definitely positive lesion group),and group c(have lesion but the diagnosis certainty is suspicious lesion group),record the location and number of lesions respectively.and select the highest activity of the lesion with abnormal imaging agent uptake at the degree level,outline the area of interest(RIO)and record the values of SUVmax and SUVmean.Based on reasonable grouping assumptions,the suspicious lesions are classified as false-positive lesions,and the number of positive and negative patients detected by MRI and PSMA-PET/CT are counted.Then we repeat the hypothetical process,the suspicious lesions are classified as the true-positive group,and the number of positive and negative patients detected by the two tests are counted separately.The data was analyzed statistically using SPSS 20.0 software.The McNemar test method was used for comparison between groups,and the corresponding p values were calculated respectively.A p value<0.05 was considered statistically significant.The serum tPSA value and Gleason score were analyzed by spearman correlation with SUVmax and SUVmean of positive lesions.Finally,visually analyze the patient's images for the lesions in each patient,compare the difference in the size of the detected lesions in the same range of each patient's 18F-PSMA PET/CT and MRI images,and record the degree of matching.ResultsThe pathological results of 32 male patients all showed prostate adenocarcinoma.The average age of the patients was 65.37 years old,the average serum tPSA was 27.37 ng/ml,and the average Gleason score was 7.97.18F-PSMA PET/CT identified 93.8%(30/32)of positive cases,and all recurrences and metastases showed high uptake of the PET/CT imaging agent 18F-DCFPyL.In the same field of view as MRI,the 18F-PSMA PET/CT and MRI imaging methods compare the number of positive lesions detected.A total of 92 positive lesions were found on the MRI image(22 of which were suspicious lesions),while 102 were found by 18F-PSMA PET/CT.Positive lesions(13 of which were suspicious lesions),18F-PSMA PET/CT detected more positive and suspicious lesions.In the same visual field evaluation method,16 patients had the lesion area shown by PET/CT larger than that shown on MRI,and 5 patients had lesion area shown on MRI that was larger than PET/CT.The range shown by the two basically matched the same:11 cases.With reasonable grouping hypothesis,when suspicious lesions are classified as false-positive lesions and true-positive lesions,respectively,the p values calculated by the McNemar test method are 0.004 and 0.083,respectively,and p<0.05 is considered as a statistical difference.That is,when suspicious lesions are classified as false-positive lesions,the 18F-PSMA PET/CT group has a significant difference in the diagnosis of prostate cancer patients compared with the MRI group.Through Spearman correlation analysis,it was found that serum tPSA was positively correlated with SUVmax and SUVmean of positive lesions(rs=0.516,P=0.002;rs=0.475,P=0.006).There was no correlation between Gleason score and positive lesions SUVmax and SUVmean(rs=-0.159,P=0.384;rs=-0.119,P=0.517).ConclusionThe 18F-PSMA PET/CT imaging,which is specifically targeted for prostate cancer,has great advantages in detecting PCa primary and metastatic lesions throughout the body,especially in detecting metastatic small lymph nodes(less than 1 cm in diameter).The patient's serum tPSA has a good correlation with SUVmax and SUVmean of positive lesions.Compared with traditional imaging MRI,18F-DCPFyL PET/CT can detect more positive lesions,and if combined with the higher soft tissue resolution of MRI,it will further improve the diagnostic ability. |
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