title: Hepatic artery: variability in measurement of resistive index and systolic acceleration time in healthy volunteers.
abstract: OBJECTIVE
  To determine the intrinsic sampling variability of measurements of hepatic artery resistive index and systolic acceleration time in healthy subjects and to estimate the components of variability attributable to the sonographer, individual measurement, and subject.
  
  
  METHODS
  In a randomized, controlled (blinded) fashion, nine sonographers measured hepatic artery resistive index and systolic acceleration time in five healthy subjects by using Doppler ultrasound (US). Analysis of variance was used to estimate the contribution of several factors to the observed variability in measurements.
  
  
  RESULTS
  The standard 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 0.0050 (76%) for the subject, sonographer, and intrinsic variability, respectively. For systolic acceleration time, the estimated variance components were 59 msec (4%), 264 msec (17%), and 1,250 msec (79%) for the subject, sonographer, and intrinsic variability, respectively.
  
  
  CONCLUSIONS
  Because of substantial variability in hepatic arterial measures, caution is indicated when interpreting small changes in the measurement of these Doppler US indexes.
authors: Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
authors: E K
authors: EK
authors: Paulson
authors: M A
authors: MA
authors: Kliewer
authors: M G
authors: MG
authors: Frederick
authors: M T
authors: MT
authors: Keogan
authors: D M
authors: DM
authors: Delong
authors: R C
authors: RC
authors: Nelson
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001783:Blood Flow Velocity; D005260:Female; D006499:Hepatic Artery / Q000000981:diagnostic imaging* / Q000502:physiology; D006801:Humans; D008297:Male; D015588:Observer Variation; D012016:Reference Values; D013599:Systole; D013997:Time Factors; D018616:Ultrasonography, Doppler, Duplex / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data; D014655:Vascular Resistance