Multiparametric Magnetic Resonance Imaging for Discriminating Low-Grade From High-Grade Prostate Cancer

E. Vos, T. Kobus, G. Litjens, T. Hambrock, C. de Kaa, J. Barentsz, M. Maas and T. Scheenen

Investigative Radiology (2015)

DOI PMID

Abstract

The aim of this study was to determine and validate the optimal combination of parameters derived from 3-T diffusion-weighted imaging, dynamic contrast-enhanced imaging, and magnetic resonance (MR) spectroscopic imaging for discriminating low-grade from high-grade prostate cancer (PCa).The study was approved by the institutional review board, and the need for informed consent was waived. Ninety-four patients with PCa who had undergone multiparametric MR imaging (MRI) before prostatectomy were included. Cancer was indicated on T2-weighted images, blinded to any functional data, with prostatectomy specimens as the reference standard. Tumors were classified as low grade or high grade based on Gleason score; peripheral zone (PZ) and transition zone (TZ) tumors were analyzed separately. In a development set (43 patients), the optimal combination of multiparametric MRI parameters was determined using logistic regression modeling. Subsequently, this combination was evaluated in a separate validation set (51 patients).In the PZ, the 25th percentile of apparent diffusion coefficient (ADC) derived from diffusion-weighted imaging and washout (WO25) derived from dynamic contrast-enhanced MRI offered the optimal combination of parameters. In the TZ, WO25 and the choline over spermine + creatine ratio (C/SC) derived from MR spectroscopic imaging showed the highest discriminating performance. Using the models built with the development set, 48 (74%) of 65 cancer lesions were classified correctly in the validation set.Multiparametric MRI is a useful tool for the discrimination between low-grade and high-grade PCa and performs better than any individual functional parameter in both the PZ and TZ. The 25th percentile of ADC + WO25 offered the optimal combination in the PZ, and the choline over spermine + creatine ratio + WO25 offered the optimal combination in the TZ. The ADC parameter has no additional value for the assessment of PCa aggressiveness in the TZ.

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