Transcranial Doppler Pulsatility Indices as a Measure of Diffuse Small‐Vessel Disease

Background and Purpose. Elevation in pulsatility indices (PIs) as measured by transcranial Doppler (TCD) have been postulated to reflect downstream increased vascular resistance caused by small‐vessel ischemic disease. Methods. The authors retrospectively compared TCD PIs and magnetic resonance imaging (MRI) manifestations of small‐vessel disease in 55 consecutive patients who underwent TCD studies and brain MRI within 6 months of each other during a 2‐year period. Results. Correlations between TCD middle cerebral artery PIs and MRI measures were as follows: periventricular hyperintensity (PVH) = 0.52 (P < .0001), deep white matter hyperintensity (DWMH) = 0.54 (P < .0001), lacunar disease = 0.31 (P= .02), and combined PVH/DWMH/lacunes = 0.54 (P < .0001). Correlation between pontine ischemia and vertebrobasilar PIs was 0.46 (P= .0004). Univariate analysis showed that age, elevated PI, and hypertension strongly correlated with white matter disease measures. After adjusting for these factors in a multivariate Poisson regression analysis, PI remained an independent predictor of white matter disease. Receiver operator curve analyses identified PI cut points that allowed discrimination of PVH with 89% sensitivity and 86% specificity and discrimination of DWMH with 70% sensitivity and 73% specificity. Conclusions. Elevation in PIs as measured by TCD shows strong correlation with MRI evidence of small‐vessel disease. TCD may be a useful physiologic index of the presence and severity of diffuse small‐vessel disease.