Validation of 2-dimensional ultrasound imaging protocols for measuring the masseter muscle.

Objective(s): To determine the most repeatable ultrasound imaging protocols for assessing the masseter muscle, evaluating repeatability across different scan locations, muscle contraction states, and operator positions.

Study Design: Ten adult volunteers underwent ultrasound scans, including three axial (superior/middle/inferior) and three longitudinal (anterior/middle/posterior) views on the left and right sides and in the relaxed and clenched states. Each subject was scanned twice, roughly 15 minutes apart.