Multiparametric 3T prostate magnetic resonance imaging to detect cancer: histopathological correlation using prostatectomy specimens processed in customized magnetic resonance imaging based molds

Abstract

Purpose: We determined the prostate cancer detection rate of multiparametric magnetic resonance imaging at 3T. Precise one-to-one histopathological correlation with magnetic resonance imaging was possible using prostate magnetic resonance imaging based custom printed specimen molds after radical prostatectomy.

Materials and methods: This institutional review board approved prospective study included 45 patients (mean age 60.2 years, range 49 to 75) with a mean prostate specific antigen of 6.37 ng/ml (range 2.3 to 23.7) who had biopsy proven prostate cancer (mean Gleason score of 6.7, range 6 to 9). Before prostatectomy all patients underwent prostate magnetic resonance imaging using endorectal and surface coils on a 3T scanner, which included triplane T2-weighted magnetic resonance imaging, apparent diffusion coefficient maps of diffusion weighted magnetic resonance imaging, dynamic contrast enhanced magnetic resonance imaging and spectroscopy. The prostate specimen was whole mount sectioned in a customized mold, allowing geometric alignment to magnetic resonance imaging. Tumors were mapped on magnetic resonance imaging and histopathology. Sensitivity, specificity, positive predictive value and negative predictive value of magnetic resonance imaging for cancer detection were calculated. In addition, the effects of tumor size and Gleason score on the sensitivity of multiparametric magnetic resonance imaging were evaluated.

Results: The positive predictive value of multiparametric magnetic resonance imaging to detect prostate cancer was 98%, 98% and 100% in the overall prostate, peripheral zone and central gland, respectively. The sensitivity of magnetic resonance imaging sequences was higher for tumors larger than 5 mm in diameter as well as for those with higher Gleason scores (greater than 7, p <0.05).

Conclusions: Prostate magnetic resonance imaging at 3T allows for the detection of prostate cancer. A multiparametric approach increases the predictive power of magnetic resonance imaging for diagnosis. In this study accurate correlation between multiparametric magnetic resonance imaging and histopathology was obtained by the patient specific, magnetic resonance imaging based mold technique.

Figure 1

Customized MRI-Based prostatectomy mold.

Figure 2

Illustration demonstrates region system used for MRI and whole-mount step-section histopathologic correlation. Analysis was conducted for 4 different zones of the prostate: peripheral zone (regions 1–4), central gland (regions 5, 6), anterior peripheral zone and central gland (regions 1, 4, 5, 6) and the overall prostate gland (regions 1–6).

Figure 3

Prostate cancer in 52-year-old man. (a) Axial T2-weighted and ADC map of diffusion weighted (b) MR images demonstrate a low-signal-intensity lesion (arrow) in right mid anterior central gland lesion suspicious for cancer. K^trans (c) and k_ep (d) maps of dynamic contrast enhanced MRI localize tumor (arrow). MR spectroscopy (e) demonstrates increased ratio of choline (cho) to citrate (cit) in the right mid anterior central gland lesion (*) when compared with normal adjacent left side (+). Histopathologic slide (f) at mid prostate level confirms presence of tumor (Gleason score, 7) (black dotted line) detected on multi-parametric MRI (A = anterior, L = left, P = posterior, R = right).

Figure 3

Prostate cancer in 52-year-old man. (a) Axial T2-weighted and ADC map of diffusion weighted (b) MR images demonstrate a low-signal-intensity lesion (arrow) in right mid anterior central gland lesion suspicious for cancer. K^trans (c) and k_ep (d) maps of dynamic contrast enhanced MRI localize tumor (arrow). MR spectroscopy (e) demonstrates increased ratio of choline (cho) to citrate (cit) in the right mid anterior central gland lesion (*) when compared with normal adjacent left side (+). Histopathologic slide (f) at mid prostate level confirms presence of tumor (Gleason score, 7) (black dotted line) detected on multi-parametric MRI (A = anterior, L = left, P = posterior, R = right).