Cerebral Microhemorrhages on Susceptibility Weighted Imaging After Aortic Dissection

Abstract

Cerebral microhemorrhages (CMHs) are detected on susceptibility weighted (SWI) and gradient recalled echo T2* (GRE-T2*) magnetic resonance imaging (MRI) and are useful biomarkers of microvascular diseases of the brain. Here we describe the characteristics and distribution of cerebral microhemorrhages in a series of subjects with aortic dissection, compared with an age- and sex-matched series of patient with severe, chronic hypertension. CMHs were discovered in 75% of subjects with aortic dissection with a median of 8 per subject and an average diameter of 2.6 mm. CMHs were primarily located within the frontal lobes, parietal lobes and deep white matter tracts in a pattern suggestive of a watershed distribution. The pattern of CMHs after aortic dissection was different from that related to severe hypertension, which may suggest a different mechanism. We propose that injury to distal arterioles from cholesterol micro emboli may account for the pattern of CMH observed after aortic dissection. Aortic dissection is an important mimicker of the neuroimaging findings of cerebral amyloid angiopathy and severe hypertension.