Type:
Educational Exhibit
Keywords:
Not applicable, Osteoporosis, Screening, Absorptiometry / Bone densitometry, Musculoskeletal soft tissue, Musculoskeletal
Authors:
S. Srinivasan, H. Chou, A. Kannivelu; SINGAPORE/SG
DOI:
10.26044/ecr2020/C-13494
Findings and procedure details
Body composition and applications:
Fig. 6: Overview of DEXA applications
Normal adults, metabolic syndrome and obesity:
Fat quantification and fat masss indices are better markers than body mass index (BMI). Lean mss index [appendicular lean mass=(arm+leg lean mass)/ht2]. Viseral fat can be separately quantified as well. (Fig. 7).
Obesity can be easily diagnosed even if BMI is normal (Fig.8).
Fraility and sarcopenia:
Definition (As per EWGSOP2) Sarcopenia was defined as 1. Low muscle strength by Hand grip strength and 2. Low muscle quantity and quality by Skeletal muscle index.
Cut-off value according to the Asia working group for Sarcopenia (AWGS) criteria for
- low muscle strength-hand grip strength below 18 kg in women and below 26 kg in men and
- low muscle mass ( Skeletal muscle index (SMI) below 5.4 kg/m2 in women and below 7.0 kg/m2 in men)
Dual energy x-ray absorptiometry (DEXA) is the gold standard imaging modality in the evaluation of sarcopenia (for calculating SMI) and has been used for the greatest number of trials.
(Fig. 9).
Usefulness in sports imagnig:
DEXA has a special role in evaluating sports been used to assess relative energy deficiency in sport (RED-S) by measuring BMD and also fat and muscle mass. It has also been used too look for lean mass symmetry on performance of skiers with ACL injuries and Australian football players.
Limitations of DEXA (for body composition):
1. Reference data of multiple ethnic groups across the world still not available (presently based on US population).
2. Lack of phantoms for absolute caliberation for fat mass quantification.
3. Very high BMI patients - whole body assessment is not possible (have to be scanned for one half of the body and data has to be extrapolated).