DEXA Data Interpretation & Reporting 5 — Questions and Answers
Question 1: A DEXA report notes that the patient's hip prosthesis prevents analysis of the right total hip. What is the recommended alternative measurement site?
- Ward's triangle on the same hip
- Contralateral (left) total hip or lumbar spine (Correct answer)
- Calcaneus on the affected side
- Whole body scan only
Correct answer: Contralateral (left) total hip or lumbar spine
If one hip cannot be analyzed due to hardware, the contralateral hip or lumbar spine should be used as the primary measurement site.
Question 2: Which of the following best describes the clinical significance of a Vertebral Fracture Assessment (VFA) finding of Grade 2 (moderate) vertebral fracture?
- Less than 20% height reduction — clinically insignificant
- 20–40% height reduction of the vertebral body — reclassifies patient to high fracture risk regardless of BMD (Correct answer)
- Greater than 40% height reduction — patient must be hospitalized
- Grade 2 refers to artifact, not a true fracture
Correct answer: 20–40% height reduction of the vertebral body — reclassifies patient to high fracture risk regardless of BMD
A Grade 2 (moderate) vertebral fracture indicates 20–40% vertebral height reduction and immediately reclassifies the patient as high fracture risk, which influences treatment decisions.
Question 3: When a DEXA report shows progressive bone loss over three serial scans despite treatment, what additional reporting element is most clinically useful to include?
- A note on scanner calibration date only
- Cumulative percentage change from baseline and comment on treatment response (Correct answer)
- Z-score comparison to age-matched peers only
- Whole-body fat percentage trend
Correct answer: Cumulative percentage change from baseline and comment on treatment response
Reporting cumulative percentage change from baseline and noting inadequate treatment response helps clinicians decide whether to reassess therapy or adherence.
Question 4: A DEXA report lists a patient's femoral neck T-score as -2.4 and total hip T-score as -2.6. The reporting technologist should base the diagnostic classification on:
- Femoral neck only, as it is the reference site for FRAX
- The lowest T-score, which is the total hip at -2.6, indicating osteoporosis (Correct answer)
- The average of both hip sub-regions
- Neither — hip T-scores are always secondary to lumbar spine
Correct answer: The lowest T-score, which is the total hip at -2.6, indicating osteoporosis
The diagnosis is based on the lowest T-score across all valid sites; a total hip T-score of -2.6 meets the WHO threshold for osteoporosis.
Question 5: A facility reports that its root mean square standard deviation (RMS-SD) precision is 0.012 g/cm² for femoral neck BMD. What is the Least Significant Change (LSC) at the 95% confidence level?
- 0.012 g/cm²
- 0.017 g/cm²
- 0.033 g/cm² (Correct answer)
- 0.024 g/cm²
Correct answer: 0.033 g/cm²
LSC at 95% CI = 2.77 × RMS-SD; 2.77 × 0.012 = 0.033 g/cm².
Question 6: In a DEXA body composition report, android fat distribution is associated with which increased health risk compared to gynoid fat distribution?
- Higher risk of osteoporosis
- Higher cardiometabolic risk including insulin resistance and cardiovascular disease (Correct answer)
- Lower risk of sarcopenia
- Higher bone mineral density
Correct answer: Higher cardiometabolic risk including insulin resistance and cardiovascular disease
Android (central/abdominal) fat distribution is associated with significantly higher cardiometabolic risk, including type 2 diabetes and cardiovascular disease.
Question 7: A DEXA report should always include which of the following elements to be considered a complete and actionable clinical document?
- Patient's dietary calcium intake and vitamin D level
- BMD values, T-scores, Z-scores, comparison to prior if available, and clinical interpretation (Correct answer)
- Only the T-score and a fracture probability percentage
- Scanner model, technologist name, and kV settings only
Correct answer: BMD values, T-scores, Z-scores, comparison to prior if available, and clinical interpretation
A complete DEXA report includes BMD values, T-scores, Z-scores, comparison to prior studies when available, and a clinical interpretation or impression.
DEXA Data Interpretation & Reporting 5
A DEXA report notes that the patient's hip prosthesis prevents analysis of the right total hip.
What is the recommended alternative measurement site?