Staging prostate cancer with dynamic contrast-enhanced endorectal MR imaging prior to radical prostatectomy: experienced versus less experienced readers

Abstract

Purpose: 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.

Materials and methods: 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.

Results: 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).

Conclusion: 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.