Given the proven efficacy of pharmacologic therapy, the role of imaging to appropriately identify and monitor high-risk individuals is critical in substantially reducing osteoporosis-associated morbidity and mortality. Special Imaging Considerations Dual-energy X-ray absorptiometry (DXA) is the mainstay of bone densitometry to screen for osteopenia and osteoporosis. Because this modality relies on precision, it is essential for patients to be scanned on the same DXA machine because differences in vendor technologies prohibit a direct comparison unless cross calibration has been performed [11,12]. CT is a cross-sectional-based X-ray technology that uses tomographic technique coupled with computer processing to generate a cross-sectional image. CT has a higher sensitivity to subtle differences in electron densities than radiography and therefore creates an image with markedly improved contrast. Quantitative CT (QCT) is performed on a standard clinical scanner and is highly accurate in determining tissue density within a region of interest. Scanning sites for QCT include the lumbar spine and hip. Several studies have assessed using conventional CT scans for measurement of bone density by establishing threshold Hounsfield unit levels that are diagnostic for osteopenia and osteoporosis, but this concept remains an opportunistic use of CT and not a screening tool [13-15]. High-resolution peripheral QCT uses the same technology in a smaller dedicated machine and focuses on the distal radius and tibia. Currently, peripheral QCT studies are not approved for diagnosis aThe Ohio State University Wexner Medical Center, Columbus, Ohio. bResearch Author, Ohio State University, Columbus, Ohio. cPanel Chair, Mayo Clinic Arizona, Phoenix, Arizona. dUniversity of Wisconsin School of Medicine and Public Health, Madison, Wisconsin. eMayo Clinic, Rochester, Minnesota. fHospital for Special Surgery, New York, New York.
Osteoporosis and Bone Mineral Density. Given the proven efficacy of pharmacologic therapy, the role of imaging to appropriately identify and monitor high-risk individuals is critical in substantially reducing osteoporosis-associated morbidity and mortality. Special Imaging Considerations Dual-energy X-ray absorptiometry (DXA) is the mainstay of bone densitometry to screen for osteopenia and osteoporosis. Because this modality relies on precision, it is essential for patients to be scanned on the same DXA machine because differences in vendor technologies prohibit a direct comparison unless cross calibration has been performed [11,12]. CT is a cross-sectional-based X-ray technology that uses tomographic technique coupled with computer processing to generate a cross-sectional image. CT has a higher sensitivity to subtle differences in electron densities than radiography and therefore creates an image with markedly improved contrast. Quantitative CT (QCT) is performed on a standard clinical scanner and is highly accurate in determining tissue density within a region of interest. Scanning sites for QCT include the lumbar spine and hip. Several studies have assessed using conventional CT scans for measurement of bone density by establishing threshold Hounsfield unit levels that are diagnostic for osteopenia and osteoporosis, but this concept remains an opportunistic use of CT and not a screening tool [13-15]. High-resolution peripheral QCT uses the same technology in a smaller dedicated machine and focuses on the distal radius and tibia. Currently, peripheral QCT studies are not approved for diagnosis aThe Ohio State University Wexner Medical Center, Columbus, Ohio. bResearch Author, Ohio State University, Columbus, Ohio. cPanel Chair, Mayo Clinic Arizona, Phoenix, Arizona. dUniversity of Wisconsin School of Medicine and Public Health, Madison, Wisconsin. eMayo Clinic, Rochester, Minnesota. fHospital for Special Surgery, New York, New York.