Point-of-Care Ultrasound M-Mode Analysis Using M.mode.ify: An External Validation Study for E-point Septal Separation...

M-mode ultrasound provides high temporal resolution imaging by rendering a single scan line over time, enabling precise measurement of rapidly moving structures. Traditional M-mode is limited to real-time acquisition and cannot be applied retrospectively. M.mode.ify is a novel software tool that generates M-mode-like tracings from video data, enabling post-acquisition analysis. This study evaluates the accuracy of M.mode.ify in measuring E-point septal separation (EPSS), a key echocardiographic parameter.

We retrospectively analyzed 50 cardiac ultrasound studies from our institution's quality assurance database. Inclusion criteria required both a saved M-mode EPSS image and a parasternal long axis (PLAX) video clip. EPSS values from M-mode served as the reference standard. Two blinded reviewers independently measured EPSS using M.mode.ify. Inter-rater reliability and agreement with the standard were assessed using Pearson correlation coefficients. Absolute error was calculated to quantify measurement precision.

Of the 50 analyzed studies, 9 were excluded due to inadequate anatomical visualization. Among the 41 included studies, inter-rater correlation was strong (r = 0.90), and agreement between M.mode.ify and standard M-mode measurements was excellent (r = 0.92). The mean absolute error was 2.38 mm (SD 1.71 mm).

M.mode.ify demonstrates high accuracy and reliability in measuring EPSS retrospectively. This tool may expand the utility of ultrasound data by enabling post hoc analysis of M-mode parameters.