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

Objective: To assess the interrater reliability between seven individuals assessing quadriceps femoris cross sectional area (CSA), echo intensity (EI), and corrected echo intensity (C-EI).

Design: A retrospective subanalysis of data collected in a randomized controlled clinical trial (IRB 19-008473. NCT ID NCT04302558). Patients aged 13 to 50 years with an anterior cruciate ligament (ACL) tear requiring surgical reconstruction were assessed for cross-sectional area of the rectus femoris (RF), vastus intermedius (VI), vastus lateralis (VL), vastus medialis (VM), and vastus medialis obliquis (VMO), and EI of the RF. 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 CSA of the RF (median ICC 0.86 MD and 0.84 PT), CSA of the VMO (0.82 and 0.82), and EI mean (0.92 and 0.92). RF CSA had the smallest CV (26.512.7%), whereas subcutaneous fat had the largest CV (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.