Quantitative Computed Tomography
QCT can also be utilized to measure spinal BMD and can be performed with common CT scanners. It is less commonly used than DXA despite similar costs and accuracy (47). Although QCT has a higher radiation exposure than DXA, it is especially accurate in evaluating vertebral bones, as the scan can detect trabecular bone loss.
The scan may also help identify fractures and areas of callus formation that indicate healing fractures. One of the advantages of QCT is that it measures both cortical and trabecular BMD and the results are expressed as direct measurements of precise volumetric mineral density calculated in mg/cm3, without the need for calculating T- or Z-scores.
Other Diagnostic Tests
Other diagnostic tests are used in the diagnostic process of osteoporosis. Among these is magnetic resonance imaging (MRI), which not only can precisely identify fractures, but is also helpful in detecting indirect signs of osteoporosis, such as occult stress fractures of the proximal femur. Quantitative ultrasonography (QUS) of the calcaneus, tibia, and patella is another inexpensive diagnostic modality to assess bone health. It is not as precise as DXA or other modalities, and cannot be used to monitor disease progression. Single-photon emission computed tomography (SPECT) is accurate and specihc for bone lesions, and represents a tomographic (CT-like) bone imaging technique that offers better image contrast and more accurate lesion localization than planar bone scanning. It increases the sensitivity and specihcity of bone scanning for detection of lumbar spine lesions by 20%-50% over planar techniques.