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Non-invasive Skeletal Muscle Quantification in Small Animals Using Micro-computed Tomography
Published on: November 8, 2024
Establishment of a quantitative assessment model and web-based calculation tool for the skeletal muscle index in
Wataru Kudo1, Keita Terui1, Ayako Takenouchi1
1Department of Pediatric Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8677, Japan.
Insights
This study developed a validated quantitative model for skeletal muscle index (SMI) in children, addressing inadequate reference values. The easy-to-use tool aids in assessing pediatric muscle mass for improved clinical utility.
Area of Science:
- Pediatric Endocrinology
- Radiology
- Nutritional Science
Background:
- Skeletal muscle index (SMI) is crucial in adults but lacks validated pediatric reference values.
- Current SMI reference values in children are inadequate for reliable clinical application.
- This study addresses the need for a validated quantitative assessment model for pediatric SMI.
Purpose of the Study:
- To develop and validate a quantitative assessment model for skeletal muscle index (SMI) in children.
- To establish standard deviation (SD) curves for pediatric SMI.
- To assess the model's utility and generalizability in clinical settings.
Main Methods:
- Examined three abdominal skeletal muscle compartments to calculate SMI (SMI = skeletal muscle area/height²).
- Utilized random grouping (training/testing), polynomial regression, and mean squared error for model generation.
- Validated the model with existing SMI data and pediatric inflammatory bowel disease patient data.
Main Results:
- Analyzed data from 474 children, confirming good overlap with previously reported SMI reference values.
- Identified low Z-scores for psoas muscle index (PMI), paraspinal muscle index (PSMI), and total SMI (TSMI) in pediatric inflammatory bowel disease patients.
- Demonstrated positive correlations between SMI and nutritional markers (body weight, BMI, albumin) and negative correlation with inflammatory markers (erythrocyte sedimentation rate).
Conclusions:
- Established a validated, quantitative assessment model for pediatric SMI.
- Developed an accessible online tool for calculating Z-scores from CT-derived skeletal muscle area, age, and height.
- The model demonstrates generalizability and clinical usefulness for pediatric skeletal muscle assessment.
Background & Aims:
The skeletal muscle index (SMI) is widely used in adults. The reference values for SMI in children are inadequate and require validation in pediatric patients for clinical usefulness. Therefore, this study developed a quantitative assessment model for SMI in children using standard deviation (SD) curves and validated the model's utility and generalizability.
Methods:
We examined three compartments of the abdominal skeletal muscle region. SMI was calculated as skeletal muscle area divided by height squared for each compartment (PMI, psoas muscle index; PSMI, paraspinal muscle index; TSMI, total skeletal muscle index). The optimal model was generated using random grouping methods (training and testing), polynomial regression analysis, and the mean squared error evaluation methods. The generated model was validated with previously published SMI data and clinical data of patients with inflammatory bowel disease.
Results:
The data of 474 children were analyzed. The previously reported SMI reference values overlapped well with our model. In patients with inflammatory bowel disease, the mean (SD) Z-scores for SMI were low in boys (PMI, -1.15 [1.11]; PSMI, -1.31 [1.07]; TSMI, -0.84 [0.91]) and girls (PMI, -1.22 [1.08]; PSMI, -1.44 [1.19]; TSMI, -0.74 [1.16]). Furthermore, SMI was positively correlated with body weight, body mass index, and serum albumin level, a nutritional marker, and negatively correlated with erythrocyte sedimentation rate, an inflammatory marker.
Conclusion:
We established a quantitative assessment model for SMI and validated the model's generalizability and clinical usefulness. We generated an easy-to-use calculation tool for Z-scores from skeletal muscle area obtained from computed tomography images, age, and height information; it has been made publicly available (http://square.umin.ac.jp/ped-muscle-calc/index.html).
