Cerebral Amyloid Angiopathy With Vascular Iron Accumulation and Calcification

Background and Purpose- Previous studies of symptomatic and asymptomatic hereditary cerebral amyloid angiopathy (CAA) patients offered the possibility to study the radiological manifestations of CAA in the early stages of the disease. Recently, a striped cortex, observable as hypointense lines perpendicular to the pial surface on T₂^*-weighted 7T magnetic resonance imaging (MRI), was detected in 40% of the symptomatic hereditary CAA patients. However, the origin of these MRI contrast changes is unknown. This study aimed at defining the underlying pathology associated with the in vivo observed striped pattern. Methods- Formalin-fixed postmortem brain material including the occipital lobe of 4 hereditary cerebral hemorrhage with amyloidosis-Dutch type (HCHWA-D) cases and 6 sporadic CAA cases were selected from local neuropathology tissue collections. Depending on the availability of the material, intact hemispheres or brain slabs including the occipital lobe of these patients were screened for the presence of a striped cortex. Regions containing the striped cortex were then subjected to high-resolution 7T MRI and histopathologic examination. Results- We found 2 hereditary cerebral hemorrhage with amyloidosis-Dutch type cases and 1 sporadic CAA case with striped patterns in the occipital cortex resembling the in vivo signal. Histopathologic examination showed that the striped pattern in the cortex at 7T MRI is because of iron accumulation and calcification of penetrating arteries. The presence of both nonheme iron and calcification on penetrating arteries causes signal loss and hence the abnormal striped patterns in the cortical ribbon on T₂^*-weighted MRI. Conclusions- We identified iron accumulation and calcification of the vessel wall in hereditary cerebral hemorrhage with amyloidosis-Dutch type as the histopathologic correlates of the striped cortex observed on in vivo 7T MRI.