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

Abstract

Objective

To determine whether dual energy x-ray absorptiometry (DXA) compared to magnetic resonance imaging (MRI) may accurately quantify trunk lean mass (LM) after chronic spinal cord injury (SCI) and to investigate the relationships between trunk LM, visceral adiposity, trunk fat mass and basal metabolic rate (BMR).

Design

Cross-sectional design and correlational analysis.

Setting

Research setting in a medical center.

Participants

Twenty-two men with motor complete paraplegia (n = 14; T4-T11) and tetraplegia (n = 8; C5-C7) were recruited as part of a clinical trial.

Interventions

Not applicable.

Outcome Measures

Trunk and android LM were measured using DXA. The volume of six trunk muscle groups were then measured using MRI to quantify trunk LM-MRI. Subcutaneous and visceral adipose tissue (VAT) cross-sectional areas were also measured using MRI. After overnight fast, BMR was evaluated using indirect calorimetry.

Results

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). Trunk LM-MRI = 0.088* log (trunk LM-DXA)-0.415; r²=0.29, SEE= 0.44 kg, P = 0.007. Trunk LM-MRI = 1.53* android LM-DXA + 0.126; r²=0.26, SEE= 0.21 kg, P = 0.018. 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). Only trunk LM-DXA was related to BMR (r = 0.61, P = 0.002). Persons with tetraplegia have 13% smaller trunk muscle cross-sectional areas (P = 0.036) compared to those with paraplegia.

Conclusions

Trunk LM-DXA and android LM-DXA overestimated trunk LM-MRI. Percentage trunk LM-MRI, but not LM-DXA, was inversely related to trunk central adiposity. The findings highlight the importance of exercising trunk LM to attenuate cardio-metabolic disorders after SCI.

Keywords:

• Trunk lean mass
• DXA
• MRI
• Body composition
• Spinal cord injury

Acknowledgements

We would like to thank all the study participants for their time and effort. We would also 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. We would like to thank the Radiology Department and MRI technicians for providing the time and effort in collecting the scans.

Abbreviations

List of Abbreviations
AIS:	=	American spinal injury association impairment scale
BE:	=	back extensors
BMR:	=	basal metabolic rate
BMI:	=	body mass index
CSA:	=	cross-sectional area
DXA:	=	dual-energy x-ray absorptiometry
EIO:	=	external and internal obliques
ES:	=	erector spinae
IP:	=	iliopsoas
LM:	=	lean mass
LM-DXA:	=	trunk lean mass measured by DXA
LM-MRI:	=	trunk lean mass measured by MRI
MF:	=	multifidus
MRI:	=	magnetic resonance imaging
QL:	=	quadratus lumborum
RA:	=	rectus abdominis
SAT:	=	subcutaneous adipose tissue
SCI:	=	spinal cord injury
VAT:	=	visceral adipose tissue

Disclaimer statements

Contributors None.

Funding The work is supported by the Department of Veteran Affairs, Office of Rehabilitation Research and Development Service, Award # B7867-W.

Conflicts of interest None.

Ethics approval None.

ORCID

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

Supplies

a. PW-630U; Tanita Corporation of America, Inc, 2625 South Clearbook Dr, Arlington Heights, IL 60005.

b. Lunar Prodigy Advance Dual-Energy X-Ray Absorptiometry (DXA) scanner; Genral Electric, PO Box 7550, Madison, WI 53707-7550.

c. Dietary intake data were collected and analyzed using Nutrition Data System for Research software version 2014, developed by the Nutrition Coordinating Center (NCC), University of Minnesota, Minneapolis, MN, 55455.

d. Cosmed K4b2- COSMED USA, Inc. 2211 N Elston Ave Ste 305, Chicago, IL 60614

e. IBM Corp. Released 2012. IBM SPSS Statistics for Windows, Version 21.0. Armonk, NY: IBM Corp.