The Value of MRI before Prostate Biopsy nosis of prostate cancer. MATERIALS AND METHODS From March 2009 to June 2010, the study was conducted on 154 patients who underwent prostate biopsy and MRI. Among the 154 patients, 51 patients underwent MRI be- fore prostate biopsy (group 1) and 103 patients underwent MRI after prostate biopsy (group 2). 　In all patients, digital rectal examination (DRE), serum prostate-specific antigen (PSA) measurement, transrectal prostate ultrasonography (TRUS), and MRI were per- formed at our outpatient clinic. DRE and TRUS examina- tion were performed by a single experienced urologist. 1. Prostate biopsy protocol Before the biopsy procedure, oral quinolone agents were administered to all patients to prevent infection caused by the procedures. All patients assumed the left down lateral decubitus position with their knees brought up toward their chest, and a transrectal ultrasound probe was in- serted through the anus. The prostate was examined by 7 MHz ultrasound. The peripheral zone mid-gray image of the prostate was optimized. Axial assessment from the base to the apex and sagittal planes assessment were done. Prostate biopsy was performed by using a standard spring-loaded biopsy device. According to the extended 10 to 12 core biopsy, it was performed on the bilateral base, midgland, and apex of the peripheral zone. If hypoechoic lesions were detected within an echo view, biopsy samples were obtained. In addition, targeted biopsies were per- formed in the abnormal regions of the MRI. Biopsy samples were labeled according to their location and were immedi- ately stored. 2. Prostate MRI protocol For prostate MRI, the 3-Tesla MR image system (A Tim System MAGNETOM Verio; SIEMENS, Germany) was used. No enema, drug administration, or other pretreat- ments were performed except that the patients fasted for 8 hours before MRI. The images were assessed by two radi- ologists with more than 15 years of experience. They dis- cussed the radiologic findings with each other and con- firmed the report after discussion. The four sequences eval- uated in this study were axial T1WI, T2WI, DWI, and ADC map. Imaging parameters for the axial T1-weighted fast spin-echo (FSE) images were repetition/echo time (TR/TE) 600/13 ms, echo train length (ETL) 3, number of excitations (average) 3, matrix size 320x224, plain resolution 0.7x0.5 mm, slice thickness 3 mm (Voxel size: 0.7x0.5x3), and ac- quisition time 3 min 23 seconds. Axial T2-weighted FSE images were TR/TE 3,060/102 ms, ETL 21, number of ex- citations (average) 3, matrix size 324x320, plain resolution 0.7x0.5 mm, slice thickness 3 mm (Voxel size: 0.7x0.5x3), and acquisition time 2 min 33 seconds. Axial diffusion- weighted images (DWI) were TR/TE 7,300/98 ms, average 6, ETL(-), matrix size 106x77, plain resolution 1.8x1.4mm, 573 slice thickness 3 mm (Voxel size: 1.8x1.4x3), and acquis- ition time 5 min 29 s, with free breath. DWI was obtained by using diffusion gradients with three b values (0, 500, and 800 s/mm2) along the orthogonal three directions of the mo- tion-probing gradients. The ADC map was automatically created from the DWIs acquired at b factors of 500 and 800 s/mm2. The sensitivity encoding (GRAPPA) reduction fac- tor was two. The slice thickness was 3 mm for all sequences (Sag T2 BLADE; 4 mm). The interslice gap was 0 mm in all sequences. The field of view was 18x18 cm for sagittal se- quences and 15x15 cm for axial sequences. 3. Pathological specimens After fixing the prostatectomy specimens in formalin, the whole prostate glands were serially blocked into approx- imately 4 to 6 mm thick (5 mm average) sections from the apex to the base in the transverse planes. These specimens were then submitted in entirety for paraffin embedding as whole mounts. The average number of blocks of a radical prostatectomy specimen was 36.3 (range, 30-43) per case. After paraffin embedding, micro-sections were placed on glass slides and stained with hematoxylin-eosin. For all cases, the same pathologist assessed both the biopsy sam- ples and the radical prostatectomy specimens, while also evaluating any correlations between them. For an in- dividual cancer focus, the pathological evaluation included the cancer location, Gleason score, histologic type, tumor size, extracapsular involvement, seminal vesicle invasion, lymphatic/vascular invasion, lymph node metastasis, peri- neural/prostatic urethral invasion, and surgical margin involvement. When multiple cancer foci were present in one case, several large lesions were chosen for the patho- logical evaluation. 4. Image analysis and statistical analysis The specimen was prepared as serial blocks and examined histologically in the department of pathology. Two patholo- gists clearly marked the site where prostate cancer was lo- cated, and the result of the prostate biopsy and MRI find- ings of the site were compared. Statistical analysis was carried out by using sensitivity, specificity, and positive predictive value. RESULTS The total number of patients was 154. Of these, 51 patients TABLE 1. Basic patient characteristics Group 1 (n=51) Group 2 (n=103) Age 67.16±6.38 (56-90) 60.09±7.55 (50-82) PSA (ng/ml) 14.16±17.66 (1.02-38.9) 16.60±23.07 (1.27-52.4) Prostate 42.98±22.70 (13.8-77.3) 37.28±16.28 (14.5-68.3) volume (ml) No. of biopsy 10.24±0.65 (10-12) 10.08±0.38 (10-12) core Korean J Urol 2011;52:572-577