Table 1.
Synopsis of body composition patterns, definitions and measures used in the literature.
| Body composition patterns | Definition | Methods used to measure body composition | Method-related definition | |
|---|---|---|---|---|
| Sarcopenia (1,2) | Low skeletal muscle quantity or quality in the presence of low muscle strength | Skeletal muscle index (SMI) or skeletal muscle mass (SMM) | The cross-sectional areas (cm2) of skeletal muscles on an axial section through L3 vertebrae, is measured by manual outlining on preoperative CT scans with a preestablished density threshold (i.e., −29 to +150 HU) and then normalized for height to obtain the SMI or SMM (cm2/m2). | Low SMI or SMM |
| Psoas muscle index (PMI) | The cross-sectional areas of the bilateral psoas muscles measured by manual tracing in preoperative CT images at L3 vertebrae is normalized for height to obtain the PMI (cm2/m2). | Low PMI | ||
| Skeletal muscle area (SMA) | The cross-sectional area of the skeletal muscle is measured by manual tracing in preoperative CT images at L3 vertebrae and normalized for height to obtain the normalized SMA (mm2/m2). | Low SMA | ||
| Total psoas area (TPA) | The cross-sectional area of the bilateral psoas muscles is measured by manual tracing in preoperative CT images at L3 vertebrae and normalized for height to obtain the normalized TPA (mm2/m2). | Low TPA | ||
| Total psoas volume (TPV) | TPV (cm3) is measured by hand tracing the borders of the entire psoas muscles for the total psoas length in preoperative CT scan and then normalizing by height (cm3/m) | Low TPV | ||
| Intramuscular adipose tissue content (IMAC) |
The cross-sectional area of CT scan at L3 vertebrae is measured to identify abdominal adipose tissue based on specific attenuation (Visceral adipose tissue: -150 to -50 HU). IMAC = CT attenuation of the multifidus and/or erector spinae muscles (HU)/CT attenuation of subcutaneous adipose tissue (HU). | High IMAC | ||
| Muscle attenuation (MA) |
The mean CT attenuation value of the cross-sectional area of the skeletal muscle (HU) in preoperative CT scan image at L3 vertebrae. | Low MA | ||
| Sarcopenic obesity | Low skeletal muscle quantity or quality and obesity | Skeletal muscle index (SMI) (cm2/m2) and body mass index (BMI) or body fat percentage (BFP). | SMI is measured as abovementioned. Obesity is measured by BMI or by BFP. Body fat percentage = [total body weight (kg) – fat-free body mass(kg)]/total body weight(kg)x100%. Total fat-free body mass (kg) = 0.30x(skeletal muscle at L3 [cm2] + 6.06). | Low SMI + obesity |
| Central or visceral obesity or visceral adiposity or visceral fat amount (11) | Visceral adipose tissue content | Visceral (intra-abdominal) adipose tissue index (VATI) | The cross-sectional area (cm2) of adipose tissue is measured by manual outlining in preoperative CT scans at L3 vertebrae or at the level of the umbilicus based on specific attenuation (-150 to -50 HU) and normalized for height (m) to obtain the VATI (cm2/m2). | high VATI |
| Visceral fat area (VFA) | The cross-sectional area (cm2) of visceral adipose tissue is measured in preoperative CT scans at L3 vertebrae or at the level of the umbilicus based on specific attenuations (-190 to -30 HU) and normalized for height (m) to obtain VFA (cm2/m2). | High VFA | ||
| visceral to subcutaneous fat area ratio (VSR) | The cross-sectional area (cm2) of subcutaneous and visceral adipose tissue are measured in CT scans at L3 vertebrae or at the level of the umbilicus based on specific attenuations (-190 to -30 HU for subcutaneous adipose tissue and -150 to -50 HU for visceral adipose tissue), then normalized for height (m). VSR= VAT area (cm2)/SAT area (cm2). | High VSR | ||
| Myosteatosis (12) | Intramuscular fat deposits | Psoas muscle attenuation (PMA) or Skeletal muscle radiation attenuation (SM-RA) | The cross-sectional preoperative CT scan image at L3 vertebrae is used to outline the area of skeletal muscle or of bilateral psoas muscles. Mean PMA or SM-RA (HU) are calculated to assess muscle fat deposition. | Low PMA or SM-RA |
| Bone mineral density (13) | BMD is the amount of bone mass per unit volume (volumetric density), or per unit area (areal density). | Bone mineral density (BMD) | The cross-sectional, non-contrast plain preoperative CT images were analyzed at the level of the Th11 vertebra. BMD was measured only on trabecular bone with calculation of the average pixel density (HU) within a circle defined as the mid vertebral core sample | Low BMD |