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.