Incidence of Diffusion-Weighted Imaging Lesions in Patients With Intracerebral Hemorrhage in the Acute and Subacute Time Periods

Background and objectives: Diffusion-weighted imaging (DWI) lesions in patients with intracerebral hemorrhage (ICH) are associated with poor outcomes. Knowledge about the underlying pathophysiology is scarce, and it is hypothesized that they are related to either the ICH itself, adverse effects of treatment, or the activity of the underlying small vessel disease (SVD) causing the ICH. We investigated their association with time point of MRI acquisition and underlying SVD type and burden. Methods: In this Swiss multicenter ICH cohort, we enrolled patients who underwent MRI within 15 days after SVD-associated ICH. The primary outcome was presence of DWI lesions. Time point of MRI was investigated as a continuous (days) and dichotomized (hyperacute = MRI on admission vs subacute = MRI during follow-up) variable. We measured cerebral amyloid angiopathy (CAA) and SVD severity using MRI burden scores and defined the type of SVD using CADMUS classification and Boston 2.0 criteria. At 3 months, we assessed functional outcome using the modified Rankin Scale score, recurrent ICH, and ischemic stroke. Discussion: DWI lesions in patients with ICH are already common at baseline. Their prevalence is higher with a longer time since symptom onset and with higher SVD burden. Overall, these findings suggest a relation with the underlying condition resulting in ICH. The significant number of DWI lesions visible on admission MRI might diminish their use as surrogate outcome in future trials in ICH.