Prediction of thigh skeletal muscle mass using dual energy x-ray absorptiometry compared to magnetic resonance imaging after spinal cord injury

Abstract

Objectives: A rapid decline in lean mass (LM), fat-free mass (FFM) and increased intramuscular fat (IMF) predispose persons with spinal cord injury (SCI) to chronic medical conditions including dyslipidemia, insulin resistance, type 2 diabetes mellitus and cardiovascular disease. (1) To determine the relationship between dual energy x ray absorptiometry (DXA) and gold standard magnetic resonance imaging (MRI) LM values; (2) to develop predictive equations based on this relationship for assessing thigh LM in persons with chronic SCI.

Study Design: Cross-sectional predicational design.

Settings: Clinical research medical center.

Participants: Thirty-two men with chronic (>1 y post-injury) motor complete SCI.

Methods: Participants completed total body DXA scans to determine thigh LM and were compared to measurements acquired from trans-axial MRI.

Outcome measures: MRI was used to measure whole muscle mass (MM_MRI-WM), absolute muscle mass (MM_MRI-ABS) after excluding IMF, and knee extensor muscle mass (MM_MRI-KE). DXA was used to measure thigh LM (LM_DXA) and (FFM_DXA). To predict MM_MRI-KE, LM_DXA was multiplied by 0.52 and yielded LM_DXA-KE.

Results: LM_DXA predicted MM_MRI-WM [r²= 0.90, standard error of the estimate (SEE) = 0.23 kg, P < 0.0001] and MM_MRI-ABS (r² = 0.82, SEE = 0.28 kg, P < 0.0001). LM_DXA-KE predicted MM_MRI-KE (r² = 0.78, SEE = 0.16 kg, P < 0.0001).

Conclusion: DXA measurements revealed an acceptable agreement with the gold standard MRI and may be a viable alternative for assessing thigh skeletal muscle mass after SCI.

Keywords:

• Spinal cord injury
• Dual energy x-ray absorptiometry
• Magnetic resonance imaging
• Lean mass

Acknowledgements

We would like to thank the participants who devoted their time and effort to participate in the current study. We would like to thank Hunter Holmes McGuire Research Institute and Spinal Cord Injury Services and Disorders for providing the environment to conduct clinical human research trials. Ashraf S. Gorgey is currently supported by the Department of Veteran Affairs, Veteran Health Administration, Rehabilitation Research and Development Service (B7867-W) and DoD-CDRMP (W81XWH-14-SCIRP-CTA).

Suppliers

Wheelchair scale (Tanita, Arlington Heights, IL)

Signa 1.5-T MRI (GE Healthcare, Chicago, IL)

X-Vessel software version 2.011 (written by Ronald Meyer at Michigan State University, Lansing, MI).

Lunar iDXA bone densitometer (GE Healthcare, Chicago, IL)

Lunar enCORE software version 16 (GE Healthcare, Chicago, IL)

SPSS, version 24 (IBM, Armonk, New York)

Disclaimer statements

Contributors None.

Funding Ashraf S. Gorgey is currently supported by the Department of Veteran Affairs, Veteran Health Administration, Rehabilitation Research and Development Service (B7867-W) and DoD-CDRMP (W81XWH-14-SCIRP-CTA).

Conflicts of interest Authors have no conflict of interests to declare.

ORCID

Ashraf S. Gorgey http://orcid.org/0000-0002-9157-6034