Intra-rater and inter-rater reliability of rehabilitative ultrasound imaging of cervical multifidus muscle in healthy people: Imaging capturing and imaging calculation

Background: Studies have analyzed muscle morphometry of cervical multifidus by using ultrasound imaging, but its reliability is not clearly determined.

Objective: To investigate intra- and inter-rater reliability of imaging capturing (probe assessment/patient positioning) and imaging calculation (scan assessment) of cervical multifidus cross sectional area (CSA) by considering the assessor's experience in asymptomatic individuals.

Design: Reliability study.

Methods: The CSA of C4/C5 cervical multifidus was assessed in 16 asymptomatic subjects. Two examiners performed the imaging capture and also repeated the procedure (probe placement/patient positioning) twice with a 10-min period between each. Other two raters conducted imaging calculations of CSA. Intra-examiner imaging capturing reliability, each rater (experienced and novice) calculated multifidus CSA of both images obtained by each examiner. Inter-examiner imaging capturing reliability, each rater calculated the CSA obtained by each examiner at the first imaging attempt. For imaging calculation reliability, each rater calculated multifidus CSA of all images captured by both examiners. Intra-class correlation coefficients (ICC) and standard error of measurement (SEM) were calculated.

Results: Intra- (ICC_3,1 0.988-0.996, SEM 0.3%-0.7%) and inter- (ICC_3,2 0.958-0.965, SEM 2.6%-3.2%) examiner reliability of imaging capturing was excellent. Intra- and inter-rater reliability of imaging calculation was also excellent for both raters (experienced/novice). No significant differences between experienced or novice examiners or testers were found.

Conclusions: This study found that intra- and inter-examiner/rater reliability of imaging capturing (probe assessment/patient positioning) and imaging calculation (scan assessment) of the cervical multifidus CSA at C4/C5 level was excellent in asymptomatic subjects.