Cadaver validation of skeletal muscle measurement by magnetic resonance imaging and computerized tomography

Abstract

Magnetic resonance imaging (MRI) and computerized tomography (CT) are promising reference methods for quantifying whole body and regional skeletal muscle mass. Earlier MRI and CT validation studies used data-acquisition techniques and data-analysis procedures now outdated, evaluated anatomic rather than adipose tissue-free skeletal muscle (ATFSM), studied only the relatively large thigh, or found unduly large estimation errors. The aim of the present study was to compare arm and leg ATFSM cross-sectional area estimates (cm2) by using standard MRI and CT acquisition and image-analysis methods with corresponding cadaver estimates. A second objective was to validate MRI and CT measurements of adipose tissue embedded within muscle (interstitial adipose tissue) and surrounding muscle (subcutaneous adipose tissue). ATFSM area (n = 119) by MRI [38.9 +/- 22.3 (SD) cm2], CT (39.7 +/- 22.8 cm2), and cadaver (39.5 +/- 23.0 cm2) were not different (P > 0.001), and both MRI and CT estimates of ATFSM were highly correlated with corresponding cadaver values [MRI: r = 0.99, SE of estimate (SEE) 3.9 cm2, P < 0.001; and CT: r = 0.99, SEE = 3.8 cm2, P < 0.001]. Similarly good results were observed between MRI- and CT-measured vs. cadaver-measured interstitial and subcutaneous adipose tissue. For MRI-ATFSM the intraobserver correlation for duplicate measurements in vivo was 0. 99 [SEE = 8.7 cm2 (2.9%), P < 0.001]. These findings strongly support the use of MRI and CT as reference methods for appendicular skeletal muscle, interstitial and subcutaneous adipose tissue measurement in vivo.

Proposal for new selection criteria considering pre‐transplant muscularity and visceral adiposity in living donor liver transplantation

“…With this software, areas of skeletal muscle, visceral, and subcutaneous adipose tissue can be easily and automatically quantified by using the CT attenuation values peculiar to these tissues. Skeletal muscle areas including psoas, erector spinae, quadratus lumborum, transversus abdominis, external and internal obliques, and rectus abdominis were identified and quantified by using attenuation values of −29 to 150 Hounsfield units (HU) (Figure 1A) 18. Skeletal muscle mass was evaluated as the skeletal muscle mass index (SMI) calculated by normalizing skeletal muscle areas to the square of the patient's height (cm 2 /m 2 ).…”

“…A higher IMAC indicates a greater amount of adipose tissue within skeletal muscle and thus a lower quality of skeletal muscle (muscle steatosis). In addition, subcutaneous and visceral adipose tissue areas were quantified by using attenuation values of −190 to −30 HU (Figure 1C) and −150 to −50 HU (Figure 1D), respectively 18, 19. VSR, which indicates visceral adiposity, was calculated by dividing visceral adipose tissue area by subcutaneous adipose tissue area 10…”

Muscle mass as a target to reduce fatigue in patients with advanced cancer

“…These muscles were identified based on their anatomic features by a trained researcher. The structures of those specific muscles were quantified based on pre‐established thresholds of Hounsfield Units (HU) (−29 to +150) of skeletal muscle tissue 30. Cross‐sectional areas (cm 2 ) of the sum of all these muscles were computed by summing tissue pixels and multiplying by the pixel surface area.…”

Changes in fat-free mass during significant weight loss: a systematic review

“…17,18 Estimates of total body potassium (TBK), although indicative of the aqueous volume of lean tissue, were also excluded owing to concern about assumptions of constant TBK/FFM ratio. 19 Finally, although multislice magnetic resonance imaging (MRI) is sensitive to changes in tissue volumes 20 and FFM, 21 it is incompatible with techniques that measure whole body fat and fat free as two compartments. Therefore, studies using MRI were excluded from the pooled analysis owing to the lack of direct quantitative comparison with UWW, DEXA or TBW.…”