Interobserver and intraobserver variation in determining intrarenal parameters by Doppler sonography

This study identified the extent of inter- and intraobserver variation in assessing intrarenal Doppler waveform parameters.Optimized Doppler waveforms from the interlobar arteries of five healthy volunteers were recorded. The waveforms were digitized for off-line evaluation by six observers. Using the same set of waveforms, the observers initially selected three of six waveforms for each subject on the basis of their preference for clinical usefulness. The observers then were directed to evaluate three previously picked waveforms. The systolic acceleration time (SAT) and the resistive index were calculated from each waveform. The observers also characterized the shape of each waveform according to four categories.Significant interobserver (p.01) but not intraobserver variation occurred when measuring the SAT. Differences were caused by the observers' perceptions of waveform shapes (kappa = .12, p.01) as well as the observers choosing different systolic starting points. No significant inter- or intraobserver variation occurred in measuring the resistive index.Much variability among and within laboratories can be expected when observers of Doppler waveforms use SAT to evaluate patients for renal artery stenosis.