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

Updated: Jan 20, 2021
  • Author: Rachel Elizabeth Whitaker Elam, MD, MSc; Chief Editor: Herbert S Diamond, MD  more...
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Answer

Compared with DXA scanning, QCT has a comparable cost [125] and precision. [115, 138, 139, 140] In addition, as with DXA, no dye injection should be used. [141] 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. [142, 143] However, QCT requires a higher radiation dose. [143]

Nonetheless, QCT scanning is less commonly used than DXA; based on US 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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