Ultrasound-based assessment of the expression of inflammatory markers in the rectus femoris muscle of rats

Bahareh Ahmadi; Felipe C K Duarte; John Srbely; Pawel M Bartlewski

doi:10.3389/ebm.2024.10064

Ultrasound-based assessment of the expression of inflammatory markers in the rectus femoris muscle of rats

Exp Biol Med (Maywood). 2024 Feb 29:249:10064. doi: 10.3389/ebm.2024.10064. eCollection 2024.

Authors

Bahareh Ahmadi¹, Felipe C K Duarte², John Srbely³, Pawel M Bartlewski¹

Affiliations

¹ Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.
² School of Health, Medical and Applied Sciences, Central Queensland University, Brisbane, QLD, Australia.
³ Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, ON, Canada.

Abstract

Ultrasonographic characteristics of skeletal muscles are related to their health status and functional capacity, but they still provide limited information on muscle composition during the inflammatory process. It has been demonstrated that an alteration in muscle composition or structure can have disparate effects on different ranges of ultrasonogram pixel intensities. Therefore, monitoring specific clusters or bands of pixel intensity values could help detect echotextural changes in skeletal muscles associated with neurogenic inflammation. Here we compare two methods of ultrasonographic image analysis, namely, the echointensity (EI) segmentation approach (EI banding method) and detection of selective pixel intensity ranges correlated with the expression of inflammatory regulators using an in-house developed computer algorithm (r-Algo). This study utilized an experimental model of neurogenic inflammation in segmentally linked myotomes (i.e., rectus femoris (RF) muscle) of rats subjected to lumbar facet injury. Our results show that there were no significant differences in RF echotextural variables for different EI bands (with 50- or 25-pixel intervals) between surgery and sham-operated rats, and no significant correlations among individual EI band pixel characteristics and protein expression of inflammatory regulators studied. However, mean numerical pixel values for the pixel intensity ranges identified with the proprietary r-Algo computer program correlated with protein expression of ERK1/2 and substance P (both 86-101-pixel ranges) and CaMKII (86-103-pixel range) in RF, and were greater (p < 0.05) in surgery rats compared with their sham-operated counterparts. Our findings indicate that computer-aided identification of specific pixel intensity ranges was critical for ultrasonographic detection of changes in the expression of inflammatory mediators in neurosegmentally-linked skeletal muscles of rats after facet injury.

Keywords: first order echotextural variables; inflammatory regulators; neurogenic inflammation; rat; rectus femoris.

MeSH terms

Animals
Image Processing, Computer-Assisted
Muscle, Skeletal / diagnostic imaging
Muscle, Skeletal / physiology
Neurogenic Inflammation*
Quadriceps Muscle* / diagnostic imaging
Rats
Ultrasonography / methods

Grants and funding

The Brazilian National Council for Scientific and Technological Development (CNPq), Canada Foundation for Innovation, and the Department of Biomedical Sciences at the University of Guelph co-funded this study. Additionally, the authors declare that this study received funding from Ontario Pork. The funder was not involved in the study design, data collection, analysis, interpretation, or the writing of this article, nor did they influence the decision to submit it for publication.