Quantification of trunk and android lean mass using dual energy x-ray absorptiometry compared to magnetic resonance imaging after spinal cord injury

The Journal of Spinal Cord Medicine, 2019 · DOI: 10.1080/10790268.2018.1438879 · Published: July 1, 2019

Spinal Cord Injury Physiology Medical Imaging

Simple Explanation

This study compares two methods, DXA and MRI, for measuring trunk lean mass in men with spinal cord injury. The researchers wanted to see if DXA, a more accessible method, could accurately measure trunk lean mass compared to MRI, the gold standard. The study also looked at the relationship between trunk lean mass, visceral fat, trunk fat mass, and basal metabolic rate. Understanding these relationships can help in developing strategies to improve health after spinal cord injury. The findings highlight the importance of trunk lean mass for persons with SCI. Advancement in imaging technology allows for a comprehensive evaluation of skeletal muscle size and composition.

Study Duration

Not specified

Participants

22 men with motor complete paraplegia (n = 14; T4-T11) and tetraplegia (n = 8; C5-C7)

Evidence Level

Cross-sectional design and correlational analysis

Key Findings

1
DXA overestimated trunk lean mass compared to MRI measurements. Trunk LM-DXA (24 ± 3.3 kg) and android LM-DXA (3.6 ± 0.7 kg) overestimated (P < 0.0001) trunk LM-MRI (1.7 ± 0.5 kg).
2
Percentage of trunk lean mass measured by MRI was inversely related to visceral fat and trunk fat mass, suggesting that lower trunk muscle mass is associated with higher central adiposity. Percentage trunk LM-MRI was inversely related to VAT (r=–0.79, P < 0.0001) and trunk fat mass (r=–0.83, P < 0.001).
3
Only trunk lean mass measured by DXA was related to basal metabolic rate. Only trunk LM-DXA was related to BMR (r = 0.61, P = 0.002).

Research Summary

This study evaluated the accuracy of DXA in quantifying trunk lean mass compared to MRI in men with SCI. The results showed that DXA overestimated trunk lean mass when compared to MRI. The study also found an inverse relationship between trunk lean mass (measured by MRI) and central adiposity (VAT and trunk fat mass). Percentage trunk LM-MRI, but not LM-DXA, was inversely related to trunk central adiposity. The findings suggest the importance of maintaining trunk lean mass in attenuating cardio-metabolic disorders after SCI and highlight the potential of using trunk LM-DXA to predict BMR. The findings highlight the importance of exercising trunk LM to attenuate cardio-metabolic disorders after SCI.

Practical Implications

Refined Measurement Techniques

Prediction equations developed in this study may help refine DXA measurements to more accurately reflect trunk muscle mass, excluding internal organs.

Rehabilitation Strategies

The inverse relationship between trunk lean mass and central adiposity emphasizes the importance of rehabilitation interventions aimed at increasing or maintaining trunk muscle mass to improve metabolic health after SCI.

Metabolic Health Monitoring

Monitoring trunk lean mass, particularly using DXA, can help predict and manage basal metabolic rate and overall metabolic health in individuals with SCI.

Study Limitations

1
Small sample size limits the generalizability of the prediction equation for trunk LM-MRI from DXA.
2
The study is restricted to men with SCI, limiting the generalizability to women.
3
The lack of an able-bodied control group limits the ability to directly compare trunk muscle size between SCI and able-bodied individuals.

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