MRI for Vascular Cognitive Disorder Risk After Cardiovascular Event

Magnetic resonance imaging of the brain may help diagnose vascular cognitive disorder following a cerebrovascular event, according to a study published in Radiology.

Researchers from the United Kingdom undertook a study to investigate associations between neuroimaging markers of cerebrovascular disease and cognition in carotid artery disease (CAD). A total of 108 patients were included in the study. All had experienced a recent nondisabling cerebrovascular event (stroke, transient ischemic attack, or amaurosis fugax) and were found to have ipsilateral carotid arterial stenosis of more than 30%, but did not have dementia.

All patients underwent brain MRI and cognitive testing with Addenbrooke’s Cognitive Examination–Revised. A score of less than 82 indicated cognitive impairment. Fifty-three of the patients were cognitively impaired.

The researchers assessed group comparison and interrelations between global cognitive and fluency performance, lesion topography, and ultrastructural damage, as well as associations between cognition, medial temporal lobe atrophy (MTA), lesion volumes, and global white matter ultrastructural damage.

“If vascular cognitive disorder follows a major stroke, the cognitive impairment typically develops suddenly, and can thus be well recognized,” study co-author Dewen Meng, MSc, from the University of Nottingham in Nottingham, said in a release. “In the majority of cases such a clear association is lacking, explaining why the detection of vascular cognitive disorder remains challenging.”[[{"type":"media","view_mode":"media_crop","fid":"51902","attributes":{"alt":"","class":"media-image media-image-right","id":"media_crop_603696834117","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"6419","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"height: 274px; width: 200px; border-width: 0px; border-style: solid; margin: 1px; float: right;","title":"(a) Infarction maps in patients with normal cognition and those with abnormal cognition. Maps were superimposed onto the 1 X 1 X 1-mm MNI152 standard-space T1-weighted average structural template. The color bars show the variation between the minimum and maximum number of lesions. Z score maps represent the result of group comparison between patients with normal cognition and those with abnormal cognition. The significant voxels (according to results of the Fisher test) did not survive the false discovery rate correction. The color bar of the Z score maps shows the variation in Z score between the minimum and maximum values. (b) Chronic subcortical ischemic lesion frequency maps in patients with normal cognition and those with abnormal cognition. Details are the same as for a. Image provided courtesy of Radiology. ©RSNA 2016.","typeof":"foaf:Image"}}]]

The results showed that the cognitively impaired patients, who were classified as having probable vascular cognitive disorder, were older than the nonimpaired patients and had more frequent medial temporal lobe atrophy (MTA). They also had more cortical infarctions, and larger volumes of acute and chronic subcortical ischemic lesions. Lesion volumes did not correlate with global cognitive performance. Cognitive performance did correlate with presence of chronic ischemic lesions within the interhemispheric tracts and thalamic radiation. White matter tract skeleton mean diffusivity showed the closest correlation with impaired cognitive performance, making it a promising tool for improved diagnostic accuracy of vascular cognitive disorder.

“Using standard clinical brain MRI, we found that microscopic damage of main white matter tracts allowed us to distinguish patients with symptomatic carotid artery disease and cognitive impairment from those who were cognitively intact,” study senior author, Dorothee P. Auer, PhD, from the University of Nottingham, said in the release. “Our findings mean that a simple MRI test might improve the diagnostic work-up of people with suspected vascular cognitive disorder, and holds further promise to track progression of the disorder.”

The researchers concluded that subcortical white matter ischemic lesion locations and severity of ultrastructural tract damage contribute to cognitive impairment in symptomatic CAD, suggesting that subcortical disconnection within large-scale cognitive neural networks is a key mechanism of vascular cognitive disorder. “This will be a critical step in the quest for prevention of vascular dementia, by helping to identify those at risk, and by enabling imaging studies to evaluate the effectiveness of interventions,” Meng said.