How does dual-energy x-ray absorptiometry (DXA) scanning compare to quantitative CT (QCT) in the diagnosis of osteoporosis?

Updated: Sep 26, 2019
  • Author: Monique Bethel, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

Compared with DXA scanning, QCT has a comparable cost [107] and precision. [99, 120, 121, 122] In addition, as with DXA, no dye injection should be used. [123] QCT is a very sensitive technique when repeated measurements are needed to detect small changes in BMD, and modern three-dimensional (3D) QCT acquisition has a scan time less than 10 seconds for the lumbar spine or proximal femur, and there is no interference by osteophytes. [124, 125] However, QCT requires a higher radiation dose. [125]

Nonetheless, QCT scanning is less commonly used than DXA; based on Medicare data, about 5% of all BMD assessments are done with QCT scanning. Smaller, rural hospitals may favor QCT scanning, as they often already have a CT scanner for trauma cases and may not be able to afford a DXA machine as well.


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