Quantification of Adipose Tissue and Muscle Mass Based on Computed Tomography Scans: Comparison of Eight Planimetric and Diametric Techniques Including a Step-By-Step Guide

Abstract

Background: Recent scientific work proved that knowledge about body composition beyond the body mass index is essential. Both adipose tissue and muscular status are determining risk factors of morbidity and mortality. Analysis of single cross-sectional computed tomography (CT) images, acquired during routine care only to prevent additional radiation exposure, provide a detailed insight into the body composition of chronically and critically ill patients. Methods: This retrospective study included 490 trauma patients of whom a whole-body multiple detector CT scan was acquired at admission. From a single cross-sectional CT, we compared eight diametric and planimetric techniques for the assessment of core muscle mass as well as visceral and subcutaneous adipose tissue. Furthermore, we derived formulas for converting the measurement results of various techniques into each other. Results: For intra- and interobserver reliability, we obtained intraclass correlation coefficients (ICCs) ranging from 0.947 to 0.997 (intraobserver reliability) and from 0.850 to 0.998 (interobserver reliability) for planimetric measurements. Diametric techniques conferred lower ICCs with 0.851–0.995 and 0.833–0.971, respectively. Overall, area-based measurements of abdominal adipose tissue yielded highly correlated results with diametric measures of obesity. For example, the Pearson correlation of visceral adipose tissue and sagittal abdominal diameter was 0.87 for male and 0.82 for female patients. Planimetric and diametric muscle measurements correlated best for lean psoas area and bilateral diametric measurement of the psoas with a Pearson correlation of 0.90 and 0.93 for male and female patients, respectively. Conclusion: Planimetric measurements should remain the gold standard to describe fat and muscle compartments. Diametric measurements could however serve as a surrogate if planimetric techniques are not readily available or feasible as for example in large registries.

Obesity Is Not an Independent Predictor of Necrotizing Soft Tissue Infection Outcomes

“…However, BMI has been criticized as an unreliable estimation of fat content in the body. Thus, in addition to BMI, we also looked at both subcutaneous and visceral fat thicknesses on CT scans in our study, and this has been shown to be a more accurate approximation of total fat content [13][14][15][16]. This is the first study to utilize these tools to determine if obesity is a factor in NSTI clinical outcome.…”

“…Two components of abdominal fat were measured, subcutaneous and visceral fat. The subcutaneous fat thickness of the abdominal wall was measured on CT at the L4/L5 lumbar vertebra as identified by the most superior aspect of iliac crest, as described previously [13,14]. Two measurements were made using the electronic medical record's measurement tool on the abdominal pannus, on either side of the vertebra.…”

Diagnostic performance of waist-to-height ratio in identifying cardiovascular risk factors and metabolic syndrome among adult Saudis

“…On the contrary, anthropometric proxies can be obtained simply and a growing evidence of their diagnostic performance encouraged clinicians to use them to avoid exposing their patients to CT hazards. 4 Analyses to verify the performance of each anthropometric index as a CVD risks screening tool in adults showed that waist-to-height ratio (WHtR) is consistently better than waist circumference (WC) or body mass index (BMI). In 2008, a metaanalysis including 88,000 participants from different populations supported the evidence that WHtR is a promising tool in discriminating CVD risks related to central obesity.…”

Sarcopenic obesity and post‐operative morbidity after pancreatic surgery: a cohort study

“…Sarcopenic obesity was defined as patients who fulfilled the skeletal muscle index (SMI) threshold for SARC as well as a BMI >25 kg/m 2 , the accepted definition of obesity in Asian cohorts . Visceral adipose tissue measurements were not used to define obesity because a standard has yet to be validated . Furthermore, using readily available BMI measurements may offer better clinical translatability.…”