Assessment of Interrater Reliability for Interpretation of Musculoskeletal Ultrasound Imaging of the Quadriceps Femoris.

Objective: The aim of the study was to assess the interrater reliability between seven individuals assessing quadriceps femoris cross-sectional area, echo intensity, and corrected echo intensity.

Design: A retrospective subanalysis of data collected in a randomized controlled clinical trial (IRB 19-008473. NCT ID NCT04302558). Patients aged 13-50 yrs with an anterior cruciate ligament tear requiring surgical reconstruction were assessed for cross-sectional area of the rectus femoris, vastus intermedius, vastus lateralis, vastus medialis, and vastus medialis obliquis, and echo intensity of the rectus femoris. Musculoskeletal ultrasound imaging of the quadriceps was performed by one physical therapist, and quantitative assessments were performed by four physicians and three physical therapists.

Results: Physicians and physical therapists had good reliability for cross-sectional area of the rectus femoris (median interclass correlation 0.86 doctor of medicine (MD) and 0.84 physical therapist), cross-sectional area of the vastus medialis obliquis (0.82 and 0.82), and echo intensity mean (0.92 and 0.92). Rectus femoris cross-sectional area had the smallest coefficient of variation (26.512.7%), whereas subcutaneous fat had the largest coefficient of variation (93.3% left, 86.4% middle, 86.1% right).

Conclusions: These findings demonstrate reliability between physicians and physical therapists in interpretation of ultrasound images of the quadriceps. The inconsistency demonstrates the need for a consistent training across disciplines to ensure accurate image interpretation.