Observer variability in the measurement of the size of intracranial aneurysms using power TCD

This study assessed the observer variability for measurement of intracranial aneurysmal size visualized on color "power" Transcranial Doppler Ultrasound (TCD). Patients with recent subarachnoid hemorrhage underwent 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 (systolic) and minimum (end diastolic) area of each aneurysm, and an adjacent reference artery. Each observer was blind to the other's results. Interobserver variability was assessed using the Bland and Altman technique. Thirty-nine aneurysms were identified in 32 patients in 10 months. The maximum cross-sectional area of the aneurysm was 38:41 mm2 (observer 1:observer 2), and the mean difference was -3 mm2 (95% confidence interval [CI] of the difference -5.4-1.46 mm2). The maximum cross-sectional area of the reference artery was 26:28 mm2 (observer 1:observer 2), and the mean difference was -2 mm2 (95% CI -5.7-1.2 mm2). Neither difference was significant. Intraobserver reliability also was good. The measurement of intracranial aneurysm and artery size with power TCD is reliable sufficiently for use in longitudinal studies of changes in aneurysm size.