Differentiation of Normal Prostate Tissue, Prostatitis, and Prostate Cancer: Correlation between Diffusion-weighted Imaging and MR-guided Biopsy
M. Schouten, K. Nagel, T. Hambrock, C. Hoeks, G. Litjens, J. Barentsz and J. Fütterer
Annual Meeting of the Radiological Society of North America (2011)
PURPOSE To prospectively discriminate between normal prostate tissue, prostatitis and prostate cancer, based on apparent diffusion coefficient (ADC)-values, using MR-guided biopsy specimens as the standard of reference. METHOD AND MATERIALS The requirement to obtain institutional review board approval was waived. MR-guided biopsies were performed in 130 consecutive patients with cancer suspicious regions (CSRs) on multi-parametric MR imaging at 3T. Exclusion criteria were patients with suspicion of prostate cancer recurrence after therapy, and biopsy specimens which could not be categorized within the following histopathological groups: normal prostate tissue, prostatitis and prostate cancer. During the biopsy procedure, an axial diffusion-weighted sequence was acquired with construction of ADC maps (TR/TE, 2000/67 ms; section thickness of 4 mm; in-plane resolution, 1.8 x 1.8 mm and b-values of 0, 100, 500 and 800 s/mm2). To verify the biopsy location, a confirmation scan with the needle left in situ was acquired. This confirmation scan was projected on the calculated ADC map in order to draw a region-of-interest (ROI) on the ADC map, representing the biopsied CSR. The obtained ADC-values of this ROI were compared with the histological outcomes of the biopsy specimens. A one-way ANOVA with post-hoc comparison was used to test for ADC-value differences among the three histological groups. Differences were considered to be significant at p<.05. RESULTS In total 85 out of 130 patients were included in this study. The median ADC-values differed significantly (ANOVA, p<0.001) across normal prostate tissue (1.05x10-3 mm2/s, SD?0.17), prostatitis (1.13x10-3 mm2/s, SD?0.19) and prostate cancer (0.86x10-3 mm2/s, SD?0.13). Bonferroni post-hoc comparisons of the three groups showed that there is a statistically significant difference in median ADC-values of prostate tissue with prostatitis and prostate cancer in the peripheral zone (p<0.001) and the central gland (p=0.03). Furthermore, a statistically significant difference was found in median ADC-values of normal prostate tissue and prostate cancer in the peripheral zone (p<0.001) and the central gland (p<0.001). CONCLUSION Median ADC-values can prospectively discriminate between prostate cancer and normal prostate tissue or prostatitis. CLINICAL RELEVANCE/APPLICATION Fast non-invasive prediction of histological classification with diffusion weighted imaging in the prostate may improve patient management.