DEXA Body Composition Analysis & DXA Clinical Applications

Question 1

Which three compartments does a standard DXA body composition scan quantify?

Accepted Answer

Lean mass, fat mass, and bone mineral content

Answer

Visceral fat, subcutaneous fat, and muscle mass

Answer

Water, protein, and mineral

Answer

Intracellular fluid, extracellular fluid, and bone

Question 2

In DXA body composition analysis, the term 'android fat distribution' refers to excess fat primarily located in the:

Accepted Answer

Abdominal and trunk region

Answer

Hips and thighs

Answer

Arms and lower legs

Answer

Chest and back

Question 3

What is the Visceral Adipose Tissue (VAT) region automatically estimated by advanced DXA software typically approximated from?

Accepted Answer

The android region scan data combined with validated algorithms

Answer

A biopsy of abdominal fat

Answer

Direct measurement of the peritoneal cavity with ultrasound

Answer

MRI co-registration

Question 4

Which metric best describes the ratio of appendicular lean mass to body weight squared, commonly used to screen for sarcopenia?

Accepted Answer

Relative skeletal muscle index (RSMI)

Answer

Fat mass index (FMI)

Answer

Body mass index (BMI)

Answer

Visceral fat area (VFA)

Question 5

When performing a whole-body DXA scan for body composition, the patient's arms must be:

Accepted Answer

Positioned palms down, slightly separated from the body sides

Answer

Raised above the head to avoid overlap with the trunk

Answer

Crossed over the chest to reduce scan area

Answer

Held tightly against the thighs

Question 6

A 'total body less head' (TBLH) measurement is frequently reported in pediatric DXA because:

Accepted Answer

The head contains a disproportionately large amount of bone mass in children, skewing whole-body BMD

Answer

Children cannot hold their heads still during the scan

Answer

Head bone density is not affected by growth hormone

Answer

Radiation to the cranium is prohibited in patients under 18

Question 7

Which of the following clinical conditions is a primary indication for using DXA body composition analysis rather than a standard bone density scan?

Accepted Answer

Monitoring lean mass changes in a patient undergoing cancer cachexia treatment

Answer

Screening for osteoporosis in a 65-year-old woman

Answer

Diagnosing vertebral fracture in a post-menopausal patient

Answer

Measuring bone age in an adolescent athlete