Osteoporosis screening and major osteoporotic fracture prediction by cranial computed tomography-derived Hounsfield units: a multi-center study on opportunistic osteoporosis screening.

BACKGROUND: The incidence of osteoporosis and osteoporotic fragility fractures is increasing due to demographic changes. Therefore, early diagnosis is desirable in order to preserve bone health and prevent low-trauma fractures. Opportunistic screening for osteoporosis by frequently performed computed tomography scans could offer a potential solution. Cranial computed tomography is often performed in potential high-risk patients for osteoporosis due to frequent falls in older ages. The aim of this study was to examine the potential value of opportunistic osteoporosis screening by cranial computed tomography-derived Hounsfield units in the overall clinical context, including sustained major osteoporotic fractures, pre-existing diseases and lifestyle factors.

MATERIALS AND METHODS: This retrospective multi-center study was conducted at the Vienna Healthcare Group, an association of the main clinics of the City of Vienna, Austria. The records of patients who received both a cranial computed tomography and a dual energy X-ray absorptiometry within one year were reviewed. The cranial computed tomography scans were assessed by two observers, and the mean Hounsfield Units were calculated for the frontal bone.

RESULTS: In total, 311 patients were analyzed. Hounsfield units significantly correlated with the T scores at the lumbar spine, total hip and femoral neck, and significant differences in Hounsfield units between patients with normal bone mineral density, osteopenia and osteoporosis were observed. These relationships remained significant in the geriatric subgroup. For the lumbar spine, 606 Hounsfield units were calculated as optimal cutoff value for the prediction of osteoporosis. Patients with sustained major osteoporotic fractures had significantly lower Hounsfield units (650) compared to patients without history of major osteoporotic fracture (715).

CONCLUSIONS: Cranial computed tomography-derived Hounsfield units may assist to detect patients with densitometric osteoporosis and with major osteoporotic fractures at earlier stages, thereby facilitating early treatment and future fracture prevention.