Abstract Body: Introduction
Cerebral amyloid angiopathy (CAA) is an age-related cerebral small vessel disease that can lead to poor outcomes due to cerebral hemorrhage. The same applies to hypertensive cerebral small vessel disease (HTN-CSVD). Cerebral atrophy is a common imaging manifestation of CSVD, but its imaging patterns in both CAA and HTN-CSVD and clinical relevance have not been fully elucidated.

Hypothesis
Based on the differences in the distribution of affected vessels between CAA and HTN-CSVD, it is hypothesized that there is a spatial distribution difference in cerebral atrophy. This may lead to different clinical characteristics between the two conditions. Previous small sample studies have shown a correlation between medial temporal lobe atrophy and cognitive levels in CAA patients, which still needs further validation.

Methods
Statistical Parametric Mapping 12 was used to obtain automated, quantitative, voxel-based morphology of cerebral atrophy shown on 5.0T MRI, including total intracranial volume, gray matter volume, white matter volume and cerebrospinal fluid volume. Two-sample t test explores the differences in the spatial distribution characteristics of cerebral atrophy between 36 CAA patients and 51 HTN-CSVD patients. A voxel-wise multiple regression analysis clarifies the correlation between cerebral atrophy and cognitive decline in CAA.

Results
After adjusting for age, gender, and total intracranial volume, cerebral atrophy differences between CAA and HTN-CSVD were mainly observed in the cortex of bilateral cerebellar hemispheres and vermis (p < 0.05 FWE). There is a spatial correlation between cerebral atrophy and cognitive levels in CAA after adjusting for age, gender, and total intracranial volume. Regional brain volume in the left medial temporal lobe, insula, parietal lobe, and thalamus was associated with mini-mental state examination scores (p < 0.05 FDR), and cerebral atrophy in the left lateral temporal lobe and right cerebellar hemisphere was associated with Montreal Cognitive Assessment scores (p < 0.05 FDR).

Conclusion
Cerebral atrophy in CAA is predominantly in the cerebellum, compared to HTN-CSVD, and is independently associated with overall cognitive levels prominantly in left temporal lobe. In conclusion, this study provides valuable reference for a better understanding of the differences of cerebral atrophy between CAA and HTN-CSVD, as well as the clinical relevance of cerebral atrophy.