Investigation of neuropathologically identified cerebral microinfarcts and their effects on magnetic resonance imaging.

摘要

Microinfarcts are the most common cerebrovascular disease pathology identified in autopsy studies. The majority of microinfarcts are not visible on MRI, therefore this this work is aimed at identifying MRI markers associated with microinfarcts. To do this, we studied Mayo Clinic patients who had received MRI during life and have since come to autopsy.;In the work presented here, we first show that patients with microinfarcts at autopsy have an increased rate of gray matter loss over time on MRI, particularly in cortical watershed zones, compared to patients without microinfarcts. These patients similarly have a higher burden of macroinfarcts. However, patients with microinfarcts have similar hippocampal volumes and a similar burden of WMH compared to patients without microinfarcts.;We next aimed to investigate regional structural changes associated with microinfarcts. To do this, we first constructed an MRI atlas specifically designed to represent the cortical regions that are routinely sampled by pathologists at autopsy. We then compared our histologic findings to structural changes in the same region on antemortem MRI. We found that microinfarcts were most commonly located in the posterior hippocampus and the superior midfrontal gyrus, but did not seem to have a direct effect on gray matter volumes.;Finally, in order to eliminate the influence of pathologies arising between the time of the antemortem MRI and time of death on the pathologic outcome of interest, we aimed to develop a postmortem MRI protocol to compare histologic and postmortem MRI findings. However, we found that significant fixation artifacts compromised image quality. We performed a study to show that at least a 6 month period of time is needed to minimize fixation-related artifacts. This is useful information for future studies using ex-vivo MRI, which are of great interest to groups studying microinfarcts for the capability of higher resolution imaging.