OBSERVER VARIABILITY IN THE MEASUREMENT OF THE SIZE OF INTRACRANIAL ANEURYSMS USING POWER TCD

This study assessed the observer variability for measurement of intrac ranial aneurysmal size visualized on color ''power'' Transcranial Dopp ler Ultrasound (TCD). Patients with recent subarachnoid hemorrhage und erwent color ''power'' TCD blind to angiography. identified aneurysms were measured from the frozen image (in real time or from video tape) using the trackball function. Two observers measured the maximum (syst olic) and minimum (end diastolic) area of each aneurysm, and an adjace nt reference artery. Each observer was blind to the other's results. I nterobserver variability was assessed using the Bland and Altman techn ique. Thirty-nine aneurysms were identified in 32 patients in 10 month s. The maximum cross-sectional area of the aneurysm was 38:41 mm(2) (o bserver 1:observer 2), and the mean difference was -3 mm(2) (95% confi dence interval [CI] of the difference -5.4-1.46 mm(2)). The maximum cr oss-sectional area of the reference artery was 26:28 mm(2) (observer 1 :observer 2), and the mean difference was -2 mm(2) (95% CI -5.7-1.2 m m(2)). Neither difference was significant. Intraobserver reliability a lso was good. The measurement of intracranial aneurysm and artery size with power TCD is reliable sufficiently for use in longitudinal studi es of changes in aneurysm size.