Development and evaluation of an anatomically guided system for ultrasound image acquisition in trauma assessment

Medical care in battlefield and austere environments may require minimally trained personnel to perform complex diagnostic procedures such as ultrasound. We present a mixed reality (MR) guidance system that uses predictive anatomical modeling to assist novice operators in acquiring the extended Focused Assessment with Sonography in Trauma (eFAST).

A morphable anatomical atlas of the torso was constructed from 180 CT scans using automated segmentation, deformable registration, and regression-based mapping between internal anatomy and external anthropometry. The atlas was integrated with a portable ultrasound system and an MR headset with probe tracking to provide subject-specific holographic guidance during scanning. System accuracy was validated using imaging phantoms and evaluated in a study involving 16 novice operators performing six-window eFAST examinations using both conventional ultrasound and MR guidance across four healthy volunteers. Ultrasound images were graded by an expert clinician, and operator workload was assessed using the NASA Task Load Index.

Atlas performance showed high segmentation accuracy (Dice score $0.93\pm 0.04$ ) and in-atlas prediction errors below 10 mm using six anthropometric measures. Phantom testing demonstrated end-to-end image localization accuracy of $2.2\pm 0.6\mathrm{mm}$ . MR guidance was associated with a nonsignificant increase in correct-window acquisition (48% to 60%) and a significant improvement in diagnostic sufficiency (13% to 25%) while reducing perceived cognitive workload.

These results demonstrate the feasibility of anatomically informed MR guidance to support ultrasound acquisition by novice users and highlight its potential for trauma diagnostics in resource-limited or austere environments.