Connecting Large and Small Vessels in Cerebrovascular Disease

Abstract

Cerebrovascular disease, a major cause of stroke, cognitive decline, and dementia, involves various conditions affecting the blood vessels and circulation in the brain. This thesis focuses on intracranial atherosclerosis (ICAS) and cerebral small vessel disease (CSVD), affecting blood vessels of different sizes in the brain. Studies employing magnetic resonance imaging (MRI) have been vital in analyzing the various aspects of these diseases. Our research primarily explores several novel MRI markers for ICAS and CSVD, with a special focus on ultra-high field 7 tesla MRI markers. We aimed to study their characteristics, determinants, and cognitive correlates, while also seeking to explore the relationship between ICAS and CSVD. Data was used from the Second Manifestations of ARTerial disease-Magnetic Resonance (SMART-MR) and Memory Depression and Aging (Medea) 7T cohort studies. In the first part, we focused on intracranial vessel wall lesions, and found associations with several vascular risk factors, MRI markers of large and small vessel disease, and decreased cognitive functioning. In the second part, we focused on cerebral microinfarcts. We found that they are quite common and occur with similar frequency in memory clinic- and arterial disease patients, associated with decreased cognitive functioning, and primarily associated with MRI markers of large vessel disease. In the third part, we focused on white matter hyperintensity (WMH) shape features and observed that a more complex WMH shape associated with decreased cognitive functioning. In addition, our findings suggested that WMH shape contains additional information about the underlying pathological severity, not otherwise described by WMH volume. Lastly, we observed that reduced cerebral perfusion precedes cerebral atrophy, suggesting interventions to improve perfusion may slow atrophy. In conclusion, this thesis has provided new insights into several new MRI markers of ICAS and CSVD, leading to a better understanding of these diseases and their relationship.