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Dual Energy XRAY Absorptiometry
Aka: Dual Energy XRAY Absorptiometry, DEXA Scan, DEXA
- See Also
- Osteoporosis
- Bone Mineral Density
- Indications: Osteoporosis Evaluation
- See Bone Mineral Density
- Gold standard Osteoporosis Screening and monitoring
- Protocol: Sites for measuring bone mass
- Lumbar Vertebrae
- Assess risk of Vertebral Compression Fractures
- Screening younger patients without Osteoarthritis
- Femoral Neck
- Assess risk of Hip Fractures
- Screening older patients with Osteoarthritis
- Other locations
- Wrist
- Calcaneus
- References
- Cummings (1993) Lancet 341:72 [PubMed]
- Marshall (1996) BMJ 312:1254 [PubMed]
- Advantages
- Negligible radiation
- Accurate, reproducible predictor osteoporotic Fracture
- Excellent measure of treatment response
- Disadvantages
- Moderate cost
- Osteoarthritis interferes with Spine DEXA Scan reading
- False elevated BMD on PA Spine views in elderly
- In elderly, use hip or lateral spine views
- Scoring
- See Bone Mineral Density (T-Score and Z-Score)
- Monitoring: Osteopenia and Osteoporosis
- Recheck DEXA Scan
- Normal or only mild Osteopenia of femoral neck: Recheck DEXA in 15 years
- Moderate Osteopenia: Recheck DEXA in 5 years
- Severe Osteopenia: Recheck DEXA Scan in 1 year
- Osteoporosis: Recheck DEXA every 2 years or less
- Gourlay (2012) N Engl J Med 366(3): 225-33 [PubMed]
- Monitoring for change
- Use absolute value in grams per cm^2 from now and prior DEXA Scan (not the T-Score)
- Use Least Significant Change defined for the particular scanner used
- Calculate the difference in absolute values (g/cm^2) between now and prior DEXA Scan
- Significant difference if change in absolute value exceeds Least Significant Change
- References
- Blake (1998) Endocrinol Metab Clin North Am 27:267-88 [PubMed]
- Bracker (1998) Postgrad Med 104(4):77-86 [PubMed]
- Genant (1998) Radiographics 18:913-8 [PubMed]