DEXA Body Composition Analysis & DXA Clinical Applications 3

Question 1

Which reference database should be used when generating Z-scores for DXA body composition parameters in a 30-year-old female patient?

Accepted Answer

An age- and sex-matched reference population (Z-score)

Answer

The young-adult peak reference (T-score style)

Answer

A BMI-matched reference cohort regardless of age

Answer

The NHANES pediatric reference database

Question 2

A DXA report shows an Android/Gynoid (A/G) fat ratio of 1.4 in a 55-year-old male patient. This finding is clinically significant because:

Accepted Answer

An elevated A/G ratio is associated with increased cardiovascular and metabolic disease risk

Answer

It indicates the patient has a favorable fat distribution pattern

Answer

A/G ratios above 1.0 are normal in males and require no clinical action

Answer

This ratio reflects bone density rather than fat distribution

Question 3

For DXA body composition scans, recent food intake can affect results primarily by:

Accepted Answer

Increasing soft tissue hydration and transiently inflating lean mass measurements

Answer

Altering the patient's bone mineral density temporarily

Answer

Reducing scan image quality due to gastrointestinal gas

Answer

Causing beam hardening that overestimates fat mass

Question 4

The EWGSOP2 (European Working Group on Sarcopenia in Older People) recommends which DXA-based cutoff for low appendicular lean mass index (ALM/ht²) in men?

Accepted Answer

Less than 7.0 kg/m²

Answer

Less than 5.5 kg/m²

Answer

Less than 9.0 kg/m²

Answer

Less than 4.0 kg/m²

Question 5

When a metal implant is present in a patient's hip, the recommended approach for a DXA body composition whole-body scan is to:

Accepted Answer

Exclude the implant region from the analysis using the manufacturer's exclusion software tool

Answer

Cancel the scan entirely, as any metal invalidates the results

Answer

Double the radiation dose setting to penetrate the implant accurately

Answer

Scan only the contralateral side and mirror the results

Question 6

In pediatric DXA body composition assessment, age- and sex-specific Z-scores are reported rather than absolute values because:

Accepted Answer

Body composition changes dramatically with age and sexual maturation, requiring age-matched norms

Answer

Children's radiation dose limits prevent calculating absolute values

Answer

Absolute lean mass values are proprietary and not published for pediatric populations

Answer

DXA cannot measure fat mass accurately in patients under 18 years old

Question 7

Which of the following would most likely IMPROVE the precision (reproducibility) of serial DXA body composition measurements?

Accepted Answer

Standardizing hydration status, clothing, and patient positioning across all visits

Answer

Scanning patients at different times of day to capture circadian variation

Answer

Using different DXA manufacturers to cross-validate results

Answer

Performing scans annually rather than more frequently