Portable Versus Conventional Ultrasound: Validity And Reliability Of Rectus Femoris And Vastus Intermedius Thickness

Authors: Carlante Emerson1, Hyun K. Kim1, Brian A. Irving1, Efthymios Papadopoulos1Affiliations:1School of Kinesiology, Louisiana State University, Baton Rouge, Louisiana, US BACKGROUND: Ultrasound (U/S) provides an opportunity for routine assessment of muscle thickness in athletes and clinical populations. Although routine use of conventional U/S systems may be more feasible relative to other imaging technologies (e.g., dual x-ray absorptiometry, computed tomography, etc.), they are often too costly and/or importable. Handheld U/S devices provide a potential solution given their portability and affordability relative to conventional U/S systems, though questions remain regarding their validity and reliability. PURPOSE: To assess the validity and reliability of a handheld U/S device relative to a conventional U/S system. METHODS: Images of the rectus femoris (RF) and vastus intermedius (VI) were taken at the midpoint of the thigh of 20 participants by two different assessors, using a conventional and portable U/S. One of the assessors performed muscle thickness measurements on two separate occasions to assess test-rest reliability. Intra- and inter-rater reliability were assessed using the intraclass correlation coefficient (ICC) based on a two-way mixed-effects model with absolute agreement. The Bland-Altman method was used to assess the agreement between the two U/S devices (i.e., validity). RESULTS: ICCs ranged from 0.94 to 0.97 for intra-rater test-retest reliability and 0.968 to 0.97 for inter-rater reliability. The Bland-Altman plot demonstrated a mean difference of 0.06 ± 0.07 cm, with limits of agreement ranging from 0.21 to -0.09 for the RF. Similarly, there was a mean difference 0.07 ± 0.10 cm, with limits of agreement ranging from 0.27 to -0.13 for the VI. CONCLUSION: We demonstrated that a portable U/S device was valid and reliable relative to a conventional U/S system for measuring RF and VI thickness. Our findings support the use of portable U/S devices for routinely evaluating muscle thickness in clinical and sport settings. Conflict of InterestNo relationships reported. Supported by: Seed Grant School of Kinesiology at Louisiana State University