Inter- and Intrarater Reliability of a Novel Ultrasound Doppler Device (earlybird) for Quantitative Assessment of...

Growing interest in quantitative Doppler assessment has underscored the need for reliable, operator-independent tools to evaluate peripheral arterial circulation. This study aimed to evaluate the reliability of a novel ultrasound Doppler device (earlybird) for measuring blood-flow velocity in lower-extremity arteries and to validate its consistency across raters. We further explored multiple hemodynamic parameters derived from the Doppler spectrogram to examine their reproducibility and potential clinical applicability.

Thirty-five participants, including 25 with varying degrees of peripheral arterial disease (PAD) and 10 healthy individuals, were recruited. Four raters performed independent measurements of the peripheral blood-flow velocity in each participant (280 measurements). Six blood-flow parameters were extracted from the Doppler spectrograms: peak systolic velocity (PSV), time-averaged velocity (TAV), end-diastolic velocity (EDV), pulsatility index (PI), resistive index (RI), and acceleration time (AT). The intraclass correlation coefficient (ICC) was used to assess reliability, which was visualized in scatter plots and Bland-Altman plots with 95% limits of agreement.

Good correlation and agreement among the different raters were observed, with inter-rater reliability ranging from an ICC of 0.755-0.835 (p < 0.001). Intra-rater reliability showed poor to excellent correlation, with ICCs ranging from 0.450 to 0.961, (p < 0.001). Bland-Altman plots revealed wide 95% limits of agreement for PSV, TAV, EDV, and PI, but narrower limits for RI (-9.8% to 9.8%) and AT (-17.3% to 17.1%).

Earlybird was shown to be a reliable tool for assessing peripheral arteries across raters, with good inter- and intra-rater reliability. The angle-independent variables, RI and AT, showed narrow 95% limits of agreement, which justifies further exploration.