Prostate MR Imaging: Tissue Characterization with Pharmacokinetic Volume and Blood Flow Parameters and Correlation with Histologic Parameters

Abstract

To prospectively determine whether pharmacokinetic magnetic resonance (MR) imaging parameters correlate with histologic mean vessel density (MVD), mean vessel area (MVA), and mean interstitial area (MIA) and whether these parameters enable differentiation of prostate cancer, chronic prostatitis, and normal prostate tissue. This study was approved by the institutional review board, and informed consent was obtained from all patients. Thirty-five patients with biopsy-proved prostate cancer were examined with a dynamic contrast material-enhanced inversion-prepared dual-contrast gradient-echo sequence (temporal resolution, 1.65 seconds) at 1.5 T to calculate blood volume, interstitial volume, and blood flow. These parameters were correlated with MVD, MVA, and MIA in 95 areas (prostate cancer, n = 36; chronic prostatitis, n = 27; normal prostate tissue, n = 32). For each MR area, five 1-mm(2) squares (original magnification, x100) of the matching histologic area were analyzed. The Wilcoxon signed-rank test was used for statistical analysis. Blood volume correlated poorly with MVD (Spearman correlation coefficient, 0.252; P = .014) but did not correlate at all with MVA (P = .759). Interstitial volume did not correlate with MIA (P = .507). Blood volume differed between patients with prostate cancer and those with a normal prostate (1.49% vs 0.84%, respectively; P < .001). Interstitial volume differed between patients with chronic prostatitis and those with a normal prostate (39.00% vs 22.59%, respectively; P = .022). Blood flow differed between patients with prostate cancer and those with a normal prostate (0.97 mL/[cm(3) x min(-1)] vs 0.34 mL/[cm(3) x min(-1)], respectively; P < .001), between patients with prostate cancer and those with chronic prostatitis (0.97 mL/[cm(3) x min(-1)] vs 0.60 mL/[cm(3) x min(-1)], respectively; P = .026), and between patients with chronic prostatitis and those with a normal prostate (0.60 mL/[cm(3) x min(-1)] vs 0.34 mL/[cm(3) x min(-1)], respectively; P = .023). Blood volume and interstitial volume did not reliably correlate with the histologic parameters. Only blood flow enabled differentiation of prostate cancer, chronic prostatitis, and normal prostate tissue.