HEPATIC-ARTERY - VARIABILITY IN MEASUREMENT OF RESISTIVE INDEX AND SYSTOLIC ACCELERATION TIME IN HEALTHY-VOLUNTEERS

PURPOSE: To determine the intrinsic sampling variability of measuremen ts of hepatic artery resistive index and systolic acceleration time in healthy subjects and to estimate the components of variability attrib utable to the sonographer, individual measurement, and subject. MATERI ALS AND METHODS: In a randomized, controlled (blinded) fashion, nine s onographers measured hepatic artery resistive index and systolic accel eration time in five healthy subjects by using Doppler ultrasound (US) . Analysis of variance was used to estimate the contribution of severa l factors to the observed variability in measurements. RESULTS: The st andard deviation for a single measurement was 0.08 for resistive index and 39 msec for systolic acceleration time. For resistive index, the estimated variance components were 0.0012 (18%), 0.0004 (6%), and 0.00 50 (76%) for the subject, sonographer, and intrinsic variability, resp ectively. For systolic acceleration time, the estimated variance compo nents were 59 msec (4%), 264 msec (17%), and 1,250 msec (79%) for the subject, sonographer, and intrinsic variability, respectively. CONCLUS ION: Because of substantial variability in hepatic arterial measures, caution is indicated when interpreting small changes in the measuremen t of these Doppler US indexes.