Staging Prostate Cancer with Dynamic Contrast-enhanced Endorectal MR Imaging prior to Radical Prostatectomy: Experienced versus Less Experienced Readers

Abstract

To prospectively determine the accuracy of experienced and less experienced readers in the interpretation of combined T2-weighted fast spin-echo (SE) magnetic resonance (MR) images and dynamic contrast material-enhanced MR images compared with T2-weighted fast SE alone, with respect to differentiation of stage T2 versus stage T3 prostate carcinoma, with histologic analysis serving as the reference standard. Institutional review board approval and informed consent were obtained, and 124 consecutive men (age range, 42-74 years; median age, 63 years) with biopsy-proved prostate cancer underwent MR imaging and were candidates for radical prostatectomy. T2-weighted fast SE MR images and multisection dynamic contrast-enhanced MR images with a 2-second time resolution for the whole prostate were obtained. The T2-weighted and fused color-coded parametric dynamic contrast-enhanced MR images with T2-weighted images were evaluated prospectively and scored with regard to local extent by one experienced reader and evaluated retrospectively by two less experienced readers working in consensus by using a five-point scale; images with a score greater than or equal to four were considered indicative of T3 disease. Results were correlated with whole-mount section histopathologic findings, and receiver operating characteristics analysis was performed. Twenty-five patients were excluded because of positive findings in the lymph nodes (n = 16), preoperative biopsy-proved seminal vesicle invasion (n = 5), and an absent dynamic dataset (n = 4). Ninety-nine patients were included in this study. The overall sensitivity, specificity, and accuracy of MR staging performance in prostate cancer with dynamic contrast-enhanced MR imaging was 69% (24 of 35 patients), 97% (62 of 64 patients), and 87% (86 of 99 patients), respectively, for the experienced reader. This difference was not significant (P = .48) when results were compared with results from the T2-weighted images. Staging performance for the less experienced readers with parametric dynamic contrast-enhanced MR imaging, however, resulted in significant improvement of the area under the receiver operating characteristics curve (A(z)) compared with T2-weighted MR imaging alone (A(z) = .66 and .82, respectively; P = .01). The use of multisection dynamic contrast-enhanced MR imaging in staging prostate cancer showed significant improvement in staging performance for the less experienced readers but had no benefit for the experienced reader.