Transition zone prostate cancer: detection and localization with 3-T multiparametric MR imaging.

Abstract

To retrospectively compare transition zone (TZ) cancer detection and localization accuracy of 3-T T2-weighted magnetic resonance (MR) imaging with that of multiparametric (MP) MR imaging, with radical prostatectomy specimens as the reference standard. The informed consent requirement was waived by the institutional review board. Inclusion criteria were radical prostatectomy specimen TZ cancer larger than 0.5 cm(3) and 3-T endorectal presurgery MP MR imaging (T2-weighted imaging, diffusion-weighted [DW] imaging apparent diffusion coefficient [ADC] maps [b < 1000 sec/mm(2)], and dynamic contrast material-enhanced [DCE] MR imaging). From 197 patients with radical prostatectomy specimens, 28 patients with TZ cancer were included. Thirty-five patients without TZ cancer were randomly selected as a control group. Four radiologists randomly scored T2-weighted and DW ADC images, T2-weighted and DCE MR images, and T2-weighted, DW ADC, and DCE MR images. TZ cancer suspicion was rated on a five-point scale in six TZ regions of interest (ROIs). A score of 4-5 was considered a positive finding. A score of 4 or higher for any ROI containing TZ cancer was considered a positive detection result at the patient level. Generalized estimating equations were used to analyze detection and localization accuracy by using ROI-receiver operating characteristics (ROC) curve analyses for the latter. Gleason grade (GG) 4-5 and GG 2-3 cancers were analyzed separately. Detection accuracy did not differ between T2-weighted and MP MR imaging for all TZ cancers (68% vs 66%, P = .85), GG 4-5 TZ cancers (79% vs 72%-75%, P = .13), and GG 2-3 TZ cancers (66% vs 62%-65%, P = .47). MP MR imaging (area under the ROC curve, 0.70-0.77) did not improve T2-weighted imaging localization accuracy (AUC = 0.72) (P > .05). Use of 3-T MP MR imaging, consisting of T2-weighted imaging, DW imaging ADC maps (b values, 50, 500, and 800 sec/mm(2)), and DCE MR imaging may not improve TZ cancer detection and localization accuracy compared with T2-weighted imaging. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120281/-/DC1.