Dual-Energy X-Ray Absorptiometry Is a Valid Tool for Assessing Skeletal Muscle Mass in Older Women ,

Abstract

Assessing skeletal muscle mass (SMM) is critical in studying and detecting sarcopenia. Direct measurements by MRI or computerized tomography are expensive or high in radiation exposure. Dual-energy X-ray absorptiometry (DXA) is promising for body composition assessments, but the validity of DXA for predicting SMM in the elderly is still under investigation. The objective of this study was to assess the relationship between DXA-derived measurements of lean soft tissue mass (LSTM) and SMM in older women. Study participants were postmenopausal women (n = 101) recruited in southern Arizona. Total and regional body composition was measured using MRI and DXA (QDR4500w). The participants' mean age was 70.7 +/- 6.4 y and their mean BMI was 27.4 +/- 5.1 kg/m2. DXA-derived LSTM was highly correlated with MRI-derived SMM for the whole body (r = 0.94; P < 0.001) and leg region (r = 0.91; P < 0.001). In multivariate models, adjusting for age and DXA-derived percent fat slightly increased the amount of variance in SMM that can be explained by the DXA-derived LSTM assessments for the leg region but not for the total body. In conclusion, although the relationships between DXA measures and MRI-derived SMM vary by region of interest, the overall prediction of SMM by DXA is excellent. We conclude that DXA is a reliable method for cross-sectional assessments of SMM in older women.

Estimativa da massa muscular esquelética em mulheres idosas: validade da impedância bioelétrica

“…A BIA é atualmente o método mais utilizado para determinação da massa muscular de idosos pela sua alta velocidade no processamento das informações, por ser um método não invasivo e relativamente barato (21) e também válido em diferentes grupos populacionais (6,10,11,22) . Portanto, a BIA vem a ser um método válido para essa estimativa.…”

“…Da mesma forma, o envelhecimento populacional tem sido relatado em países desenvolvidos (2) e em desenvolvimento (3) . Uma das alterações mais associadas ao envelhecimento é a diminuição da massa muscular esquelética (MME) (4,5) , que tem sido relatada como sarcopenia, provocada pela redução da força muscular, aumento do risco de resultados adversos de saúde, como quedas e consequentes fraturas, inaptidão física e perda da autonomia na população idosa (6,7) . Para a estimativa da MME em estudos laboratoriais, têm-se utilizado a ressonância magnética e a tomografia computadorizada como métodos de referência, porém, estes apresentam limitações logísticas e financeiras que inviabilizam sua aplicação em estudos de campo (8) .…”

“…Investigações indicam que a DXA é um método válido para a estimativa da MME, tanto em homens quanto em mulheres idosas (6,9) . Entretanto, mesmo com o desenvolvimento de métodos para estimar a MME, como a DXA, os custos ainda continuam elevados.…”

Dxa as a Tool for the Assessment of Morphological Asymmetry in Athletes

“…Magnetic resonance imaging and computed tomography are regard as the reference methods for regional body composition assessment but routine use of them is impeded by access, high cost, and in case of CT, significant exposure to ionizing radiation. Some authors propose then DXA (Dual Energy X-ray absorptiometry) as a more valid and precise method for measuring total and regional body composition (Chen et al, 2007;Andreoli et al, 2009). Generally, DXA, CT and MRI methods are consider to be a standard for precision and accuracy for body composition measurements (Chettle & Fremlin, 1984;Ellis, 2000).…”

Optimal management of sarcopenia

“…DXA closely correlates with measurements achieved via MRI scanning. 12 The main limitation with DXA is that it may underestimate the extent of sarcopenia as it can overestimate skeletal muscle mass by as much as 8% due to difficulty in distinguishing muscle from water retention and muscle fat infiltration. 13 Bioelectric Impedence Analysis is a quick noninvasive method for measuring body composition via tissue conductivity.…”