CT-Detected White Matter Disease Linked to Higher Stroke, Dementia Risk
A study finds that white matter disease detected on CT scans signals a higher risk for stroke or dementia compared to MRI-only findings. CT-detected WMD may represent more advanced cerebrovascular injury, highlighting the need for modality-specific interpretation of incidentally discovered brain abnormalities.
White matter disease (WMD) detected on computed tomography (CT) was associated with a greater risk of future stroke or dementia than WMD detected only on magnetic resonance imaging (MRI), according to a study published in Neurology. The findings suggest that CT-identified WMD may represent more advanced cerebrovascular injury.
Researchers conducted a retrospective cohort study of 18,628 adults aged 50 years and older without a history of stroke or dementia who underwent both head CT and brain MRI within a 30-day period between 2009 and 2022. The cohort had a mean age of 64.9 years, 59.1% were women, and it was racially and ethnically diverse. Cardiovascular risk factors were common, including hypertension (63.3%), hypercholesterolemia (71.3%), diabetes (30.3%), and tobacco use (44.9%).
Natural language processing was used to identify covert brain infarction (CBI) and WMD from radiology reports. The prevalence of CBI was similar between CT (6.3%) and MRI (6.1%), with 91.6% agreement for presence or absence. However, WMD was detected significantly more often on MRI (60.5%) than on CT (24.4%), and agreement for WMD presence was only 57.6%. Among cases with severity classified on both modalities, 47.9% received different classifications, with MRI assigning a higher severity grade in 92.3% of discordant cases.
During a mean follow-up of 4.4 years, 985 patients experienced stroke alone, 716 developed dementia alone, and 330 had both outcomes. The incidence rate of stroke or dementia was 12.7 per 1000 person-years for patients without WMD on either modality, rising to 22.6 for MRI-only WMD, 37.0 for CT-only WMD, and 52.2 for WMD on both. After adjustment, patients with MRI-only WMD had a 23% higher risk (hazard ratio [HR], 1.23) compared to those without WMD, while the risk was 46% higher for CT-only WMD (HR, 1.46) and 82% higher for WMD on both modalities (HR, 1.82). A similar pattern was observed for CBI: MRI-only CBI carried a 47% increased risk (HR, 1.47), CT-only CBI a 26% increase (HR, 1.26), and CBI on both a 68% increase (HR, 1.68).
MRI appears to detect a broader spectrum of white matter abnormalities, including milder disease not visible on CT. In contrast, WMD identified on CT may indicate more clinically significant cerebrovascular damage, explaining its stronger association with subsequent stroke or dementia. Limitations include reliance on radiology reports rather than direct image review and inclusion of only patients who underwent both CT and MRI.