[Assessment of local staging of prostate cancer by endorectal surface coil]

We assessed the usefulness of endorectal surface coil MRI (ERSC-MRI) for staging diagnosis of prostate cancer to compare preoperative ERSC-MRI findings with pathological staging in patients performed radical prostatectomy. MR imaging was performed on a 1.5 T MR system with an endorectal surface coil designed for imaging the prostate. At the time the coil was inserted, 1.0 mg of glucagon was injected in tramuscularly. T1-weighted MR images were obtained in the axial plane, and T2-weighted, spin echo MR images were obtained in the sagittal, coronal, and axial planes for each patient. The capsular penetration of prostatic cancer was defined according to the six diagnostic criteria by Outwater et al.: (1) a bulge formation of the low-signal-intensity area beyond the prostatic capsule, (2) low-signal-intensity stranding in the periprostatic tissue, (3) retraction of the prostatic capsule besides the low-signal-intensity area, (4) elongation of the low-signal-intensity area in the prostatic capsule, (5) thickening of prostatic capsule. (6) extracapsular tumor. The sensitivity, specificity and accuracy of ERSC-MRI for capsular penetration of the prostatic cancer were 95.5%, 40.0%, and 85.2%, respectively. These results indicate that ERSC-MRI is useful for staging diagnosis of prostatic cancer.