Temporal bone thickness and texture are major determinants of the high rate of insonation failures of transcranial doppler in amerindians (the Atahualpa Project)

Purpose To assess the role of temporal bone characteristics in transcranial Doppler (TCD) insonation failures in Amerindians living in rural Ecuador. Methods We evaluated thickness and texture of temporal bones in community‐dwelling Amerindians ≥65 years old undergoing TCD. Using receiver operator characteristics curve analysis and generalized estimating equations, we investigated factors associated with insonation failures. Results Of 65 participants (mean age 74.7 ± 6.7 years, 60% women), 32 (49%) had uni‐ or bilateral insonation failure through temporal windows. Considering temporal bones independently, 57 of 130 (44%) had poor insonation. Mean thickness was higher (4.7 ± 1.2 versus 2.7 ± 0.9, p < 0.0001), and texture more often heterogeneous (93% versus 22%, p < 0.0001) in bones with poor acoustic windows. Thickness, better predicting poor insonation, was ≥3.6 mm if used alone, and ≥2.7 mm if used together with heterogeneous texture. For every millimeter of increase in thickness, subjects were 2.9 times more likely to have insonation failures. Per se, heterogeneous texture increased by 3.2 times the odds for poor insonation. In all models, being woman increased the odds for poor insonation by six to nine times. Conclusions Temporal bone thickness and texture are independent predictors of TCD insonation failure in Amerindians. © 2015 Wiley Periodicals, Inc. J Clin Ultrasound 44 :55–60, 2016