Acute diffusion-weighted imaging lesions in cerebral amyloid angiopathy-related convexal subarachnoid hemorrhage

Abstract

Small acute diffusion-weighted imaging (DWI) lesions can accompany intracerebral hemorrhage due to cerebral amyloid angiopathy (CAA). We therefore examined the occurrence of such lesions in the context of CAA-related convexal subarachnoid hemorrhage (cSAH) both in a cross-sectional and longitudinal manner. DWI lesions were noted in 14/29 (48%) patients at their index cSAH and 12/21 patients (57%) showed acute small DWI lesions at follow-up MRI. Forty-four of 71 (62%) DWI lesions were spatially related to areas of cortical superficial siderosis. Clarification of the implications of our finding needs the investigation of larger patient groups.

Keywords: Cerebral amyloid angiopathy; convexal subarachnoid hemorrhage; cortical superficial siderosis; diffusion-weighted imaging lesions; ischemic infarcts; magnetic resonance imaging.

Figure 1.

Images from an 81-year-old patient with acute convexal subarachnoid hemorrhage (cSAH) who experienced recurrent transient focal neurological episodes. (a) Linear signal hyperintensity (arrow) on fluid-attenuated inversion recovery (FLAIR) MRI with corresponding intrasulcal signal loss on the gradient echo T2* sequences (not shown) consistent with acute cSAH. Also, note cortical swelling of neighboring gyri. (b–d) Diffusion-weighted imaging revealed multiple small (2–5 mm), cortico-subcortical, round-ovoid, bright lesions (arrows) in the right parietal lobe.

Figure 2.

Serial diffusion-weighted imaging (DWI) in a 68-year-old patient with acute cSAH (not shown) during repeated transient focal neurological episodes. (a) DWI reveals multiple, cortico-subcortical, bright lesions in the frontal and parietal lobe (arrows) which were present at every follow-up MRI. (b) Corresponding apparent diffusion coefficient (ADC) maps show decreased diffusivity (arrows) consistent with acute ischemic damage.