CT vs MRI: Assessing Stroke and Dementia Risk in White Matter Disease

 

My incompetent? doctor told me I had a bunch of white matter hyperintensities but never showed me them on any scan, so I don't know the size, location or any intervention needed, because my doctor knew nothing and did nothing. I have zero cognitive impairment and I'm 20 years out.

CT vs MRI: Assessing Stroke and Dementia Risk in White Matter Disease

 Patients with incidentally discovered white matter disease on computed tomography have a higher risk for future stroke or dementia than those with disease detected only on magnetic resonance imaging. White matter disease (WMD) detected on computed tomography (CT) identified patients at greater risk for future stroke or dementia than WMD detected only on magnetic resonance imaging (MRI), according to study results published in Neurology. Covert cerebrovascular disease (CCD), which includes covert brain infarction (CBI) and WMD, is frequently identified incidentally during neuroimaging in patients without a history of stroke or dementia. Although MRI is generally considered more sensitive for detecting these abnormalities, CT remains the most commonly used neuroimaging modality in routine clinical practice. Researchers therefore compared incidentally discovered CCD detected on CT and MRI to determine whether findings from each modality differed in their association with subsequent neurologic outcomes. Researchers conducted a retrospective cohort study of adults aged 50 years and older who underwent both head CT and brain MRI within a 30-day period between 2009 and 2022. They excluded patients with a prior history of stroke or dementia, as well as those with major neurologic symptoms suggestive of acute stroke. They used natural language processing to identify CBI and WMD from radiology reports and classify WMD severity. These findings highlight the importance of modality-specific interpretation of CCD in clinical practice and research. The analysis included 18,628 participants with a mean age of 64.9 years; 59.1% were women. The cohort was racially and ethnically diverse, with 41.4% identifying as non-Hispanic White, 32.7% as Hispanic, 12.0% as Asian or Pacific Islander, and 11.3% as African American. Cardiovascular risk factors were common, including hypertension (63.3%), hypercholesterolemia (71.3%), diabetes (30.3%), and a history of tobacco use (44.9%). The prevalence of CBI was similar across imaging modalities, occurring in 6.3% of CT scans and 6.1% of MRI scans. Overall agreement for CBI presence or absence was 91.6%. Among patients with CBI on MRI, 33.3% also had CBI on CT. Among patients with CBI on CT, 31.9% also had CBI on MRI. Researchers identified WMD in 60.5% of MRI reports compared with 24.4% of CT reports. Agreement for WMD presence was 57.6%. Among patients with WMD severity classified on both modalities, 47.9% received different severity classifications, and MRI assigned a higher severity grade than CT in 92.3% of those discordant cases. During a mean follow-up period of 4.4 years, 985 patients experienced stroke alone, 716 developed dementia alone, and 330 experienced both outcomes. Patients without WMD on either imaging modality had an incidence rate of stroke or dementia of 12.7 events per 1000 person-years. Rates increased to 22.6 among patients with WMD detected only on MRI, 37.0 among those with WMD detected only on CT, and 52.2 among those with WMD detected on both CT and MRI (all per 1000 person-years). After adjustment for demographic characteristics and vascular risk factors, patients with WMD detected only on MRI had a 23% higher risk for stroke or dementia than those without WMD on either modality (hazard ratio [HR], 1.23; 95% CI, 1.07-1.41). Patients with WMD detected only on CT had an even greater risk (HR, 1.46; 95% CI, 1.11-1.92), and those with WMD identified on both modalities had the greatest risk (HR, 1.82; 95% CI, 1.58-2.11). The researchers observed a similar pattern for CBI. Compared with patients without CBI on either modality, those with MRI-only CBI had a higher adjusted risk for stroke or dementia (HR, 1.47; 95% CI, 1.23-1.76), as did patients with CT-only CBI (HR, 1.26; 95% CI, 1.04-1.53) and those with CBI detected on both modalities (HR, 1.68; 95% CI, 1.33-2.11). The researchers suggested that MRI appears to detect a broader spectrum of white matter abnormalities, including milder disease that may not be visible on CT. In contrast, WMD identified on CT may represent more advanced or clinically significant cerebrovascular injury, potentially explaining its stronger association with future stroke or dementia. Study limitations include reliance on natural language processing of radiology reports rather than direct image review and the inclusion of only patients who underwent both CT and MRI. “These findings highlight the importance of modality-specific interpretation of CCD in clinical practice and research,” the study authors concluded.  Disclosures: This research was supported by the Alzheimer’s Drug Discovery Foundation and the National Institutes of Health. One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.