Analysis of central nervous system vasculitis with diffusion-weighted imaging and apparent diffusion coefficient mapping of the normal-appearing brain.

BACKGROUND AND
PURPOSE: Diffusion-weighted imaging (DWI) is a novel method of studying the brain that creates tissue contrast secondary to water diffusion. Central nervous system (CNS) vasculitis is a rare inflammatory disease that continues to be difficult to diagnose and evaluate with MR imaging. DWI with apparent diffusion coefficient (ADC) analysis may demonstrate abnormalities within the brain that would otherwise be undetected by conventional imaging, thus aiding in the diagnosis and evaluation of patients with CNS vasculitis.
MATERIALS AND METHODS: A retrospective analysis was performed of patients who were diagnosed with CNS vasculitis and had undergone DWI. A total of 15 patients who had DWI with b = 1000 were analyzed. Regions of interest were drawn in the anterior, central, and posterior regions of white matter (WM) at 3 levels. Regions of interest were also drawn bilaterally in the caudate heads, putamina, thalami, posterior internal capsules, and the cerebellar WM. ADC values were measured and compared with 15 healthy controls who were matched for age, sex, and MR imaging scanner.
RESULTS: There was a significant increase in the ADC values (P<.00625) for the anterior WM, central WM, thalami, and posterior internal capsules in patients with CNS vasculitis.
CONCLUSION: Diffuse increase in water diffusion was present in the normal-appearing brain in patients with CNS vasculitis, and these abnormalities were not demonstrated by conventional MR imaging sequences. The detection and quantification of ADC abnormalities may provide useful diagnostic information for patients with CNS vasculitis.