Abstract WMP100: Underlying Microangiopathy of Mixed Location Intracerebral Hemorrhage and Microbleeds: a PiB-PET Study

Abstract

Background: Recent MRI-based work suggested that the predominant type of cerebral small vessel disease (SVD) in patients with a combination of lobar and deep intracerebral hemorrhage (ICH)/microbleed (MB) locations (Mixed-ICH) was hypertensive (HTN) SVD. We sought to use in vivo amyloid imaging to test the hypothesis that mixed-ICH is related to HTN-SVD rather than cerebral amyloid angiopathy (CAA). Methods: Eighty Asian primary ICH patients without dementia were included in this study. All patients underwent brain MRI and 11 C-Pittsburgh Compound B (PiB) PET. The global, occipital and frontal standardized uptake value ratio (SUVR) were calculated using cerebellum as reference. Fourty-six (51%) patients had Mixed-ICH. Their demographic and clinical profile as well as amyloid deposition patterns were compared to 13 probable CAA (Boston criteria; CAA-ICH) and 21 strictly deep-MB and ICH (HTN-ICH) patients. Results: Mixed-ICH patients were younger (62.8±11.7 vs 71.0±14.5 in CAA) and showed a higher burden of vascular risk factors such as hypertension and diabetes than CAA-ICH (all p<0.05). Patients with Mixed-ICH had lower mean global (1.11±0.2 vs 1.31±0.3), frontal (1.09±0.2 vs 1.31±0.3) and occipital SUVR (1.16±0.1 vs 1.32±0.2) than CAA-ICH (all p<0.05). In multivariable analyses, Mixed-ICH diagnosis was associated with hypertension (β=-1.09, 95% Confidence interval [CI]: - 2.5- -0.1, p=0.02) while diagnosis of probable CAA with global-SUVR (β=3.5, CI: 0.3-7.3 p=0.04) after adjustment for age. Mean frontal and occipital-SUVR measures were both associated with probable CAA diagnosis in similar multivariable models. Compared to HTN-ICH, Mixed-ICH showed a similar mean age (62.8±11.7 vs 60±14.5 in HTN-ICH) and risk factor profile (all p>0.1). Furthermore, mean global, frontal and occipital SUVR did not differ between Mixed ICH (values presented above) and HTN-ICH (1.08±0.1, 1.04±0.2 and 1.14±0.1 respectively, all p>0.1). Conclusions: In addition to validating previous results in an Asian cohort, our study also brings the unique insight that Mixed-ICH patients have much lower amyloid load than CAA-ICH, while being very similar to HTN-ICH. Overall, Mixed-ICH is probably caused by HTN-SVD, an important conclusion with clinical relevance.