The Role of b-value Diffusion-weighted Imaging in Differentiating High-grade and Low-grade Brain Tumors: A...

Accurate differentiation between high- and low-grade brain tumors is pivotal for guiding therapy and predicting prognosis. While diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) mapping offer non-invasive insights into tumor microstructures, conventional b-value (~1000 s/mm²) protocols often blur these distinctions, limiting diagnostic specificity. This study systematically investigated the impact of multiple b-values on DWI and ADC values to optimize tumor grade differentiation.

Forty patients with histologically confirmed brain tumors (18 glioblastoma multiforme, 11 astrocytoma's, 5 oligodendrogliomas, and 6 ependymomas) underwent MRI between April 2023 and March 2024 at our institution. DWI sequences were acquired at b-values of 0, 500, 1000, 1500, and 2000 s/mm². Three radiologists independently scored the images for quality, lesion conspicuities, anatomical delineations, artifacts, and noise using a 4-point Likert scale. The ADC values were correlated with histopathological grade. Inter-reader reliability was assessed using the intraclass correlation coefficient (ICC) and Cohen's kappa.

High b-values (1500-2000 s/mm²) substantially enhanced lesion conspicuity, especially in low-grade tumors, while preserving the anatomical details. The ADC values were inversely correlated with the tumor grade across all b-values (P < 0.05). The inter-reader agreement was excellent (ICC = 0.82). Compared with conventional b = 1000 s/mm² imaging, higher b-value DWI revealed subtle microstructural differences undetectable at standard diffusion weightings, improving the differentiation between tumor grades.

High-b-value DWI markedly improves noninvasive brain tumor grading by enhancing ADC contrast and lesion visibility. Integrating high-b-value protocols into routine MRI can facilitate early and accurate diagnosis, support personalized treatment planning, and potentially transform clinical neuro-oncological practice.