Repeatability of ultrasonographic measurement of cross‐sectional area of the multifidus muscle in the horse

Abstract

SummaryBackgroundRecent studies have described techniques to acquire ultrasound measurements of the cross‐sectional area of the multifidus muscle to investigate back pain in horses and monitor the response to rehabilitation. These techniques have been extrapolated from human research but have not been clinically validated in the horse.ObjectiveThe objective of the study was to investigate whether measuring the cross‐sectional area of the multifidus muscle in horses using ultrasound is a repeatable technique.Study designCross‐sectional.MethodsUltrasound images of the articular process view and interspinous view of the multifidus muscle were acquired at T15, T18, L2 and L5 on the left and right sides. Three images were acquired at each location and each image was measured three times to give an average cross‐sectional area. Study 1 investigated the repeatability of acquiring images in a single session, and then on two separate days. Study 2 compared measurements of images acquired with a console (Philips EpiQ) and a portable (MyLab™Alpha) ultrasound machine. Study 3 investigated the repeatability of measuring the cross‐sectional area using external software, OsiriX. Intraclass correlation coefficients (ICC) were calculated for each study.ResultsRepeatability varied from good to excellent for images taken in a single session. The repeatability for measuring the images using external software was good to excellent. There was poor‐to‐moderate repeatability for images taken on two different days and poor‐to‐good repeatability when using the two different machines.Main limitationsPopulation size, study population limited to a single breed, only one operator.ConclusionsThe measurement of the multifidus muscle in horses has poor repeatability and may have limited application.