Preoperative grading of supratentorial gliomas using high or standard b-value diffusion-weighted MR imaging at 3T

Purpose: The goal of this study was to compare diffusion-weighted magnetic resonance imaging (DW-MRI) using high b-value (b = 3000 s/mm(2)) to DW-MRI using standard b-value (b = 1000 s/mm(2)) in the preoperative grading of supratentorial gliomas. Materials and methods: Fifty-three patients with glioma had brain DW-MRI at 3T using two different b-values (b = 1000 s/mm(2) and b = 3000 s/mm(2)). There were 35 men and 18 women with a mean age of 40.5 +/- 17.1 years (range: 18-79 years). Mean, minimum, maximum, and range of apparent diffusion coefficient (ADC) values for solid tumor ROIs (ADC(mean), ADC(min), ADC(max), and ADC(diff)), and the normalized ADC (ADCratio) were calculated. A Kruskal-Wallis statistic with Bonferroni correction for multiple comparisons was applied to detect significant ADC parameter differences between tumor grades by including or excluding 19 patients with an oligodendroglioma. Receiver operating characteristic curve analysis was conducted to define appropriate cutoff values for grading gliomas. Results: No differences in ADC derived parameters were found between grade II and grade III gliomas. Mean ADC values using standard b-value were 1.17 +/- 0.27 x 10(-3) mm(2)/s [range: 0.63-1.61], 1.05 +/- 0.22 x 10-3 mm(2)/s [range: 0.73-1.33], and 0.86 +/- 0.23 x 10(-3) mm(2)/s [range: 0.52-1.46] for grades II, III and IV gliomas, respectively. Using high b-value, mean ADC values were 0.89 +/- 0.24 x 10-3 mm(2)/s [range: 0.42-1.25], 0.82 +/- 0.20 x 10(-3) mm(2)/s [range: 0.56-1.10], and 0.59 +/- 0.17 x 10-3mm(2)/s [ range: 0.40-1.01] for grades II, III and IV gliomas, respectively. ADC(mean), ADC(ratio), ADC(max,) and ADC(min) were different between grade II and grade IV gliomas at both standard and high b-values. Differences in ADC(mean), ADC(max), and ADC(diff) were found between grade III and grade IV only using high b-value. Conclusion: ADC parameters derived from DW-MRI using a high b-value allows a better differential diagnosis of gliomas, especially for differentiating grades III and IV, than those derived from DW-MRI using a standard b-value. (C) 2016 Editions francaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.