Prevalence of incidental DWI-positive lesions in patients with CADASIL: Restuls from the VASCAMY Study

Introduction

Due to increasing availability of MRI scans, incidental diffusion-weighted imaging (DWI)-positive lesions are increasingly recognized on brain MRI in individuals with vascular disease. Cerebral small vessel disease (SVD) is a putative cause of these lesions. We investigated the prevalence of incidental DWI-positive lesions in patients with Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL), a genetic form of SVD, which frequently manifests as subcortical infarcts at a younger age and serves as a pure disease model for sporadic SVD. Furthermore, in these patients, we assessed risk factors of incidental DWI-positive lesions, including common vascular risk factors and MRI markers of SVD.

Methods

64 patients with CADASIL and without acute (< 6 months) ischemic stroke were included from the VASCAMY study. Mean age was 51.9 years (SD 10.5) and 63% was female. Patients underwent 3T MRI at baseline, and 43 patients underwent a second MRI at 18 or 36 months. Incidental DWI- positive lesions were assessed by one expert rater on pre-processed trace images derived from diffusion MRI. At follow-up, difference imaging of the trace images was applied to allow systematic identification of new lesions. Rating was done according to STRIVE-2 criteria.

Results

At baseline, incidental DWI-positive lesions were prevalent in 13/64 (20%) patients. In total, 27/107 (25%) scans were DWI-positive, with 19/64 (30%) patients having an incidental DWI- positive lesion at any time point. Most lesions were located subcortically and were either tubular in shape, following the orientation of a perforating arteriole, or ovoid with a small cavitation. A few incidental DWI-positive lesions corresponded to recent microinfarcts. At baseline, incidental DWI- positive lesions were significantly associated with greater white matter hyperintensity volume, and presence and increased volume of lacunes (all p<.05).

Discussion

Cross-sectionally, incidental DWI-positive lesions were detected in a fifth of patients with CADASIL. Incidental DWI-positive lesions were mostly subcortical and significantly associated with MRI markers of SVD. Our findings, obtained in patients with pure SVD, i.e., without age-related co- morbidities, provide supporting evidence that subcortical incidental DWI-positive lesions are common in CADASIL and may be a feature of SVD.