Osteoporosis Diagnosis With Hounsfield Units?

Regional cancellous bone mineral density (BMD) can be approximated from Hounsfield units (HU) measured on CT examinations using automatic exposure control; this information is reliable and follows a predictable pattern with increasing age. HU from clinical CT scans that are obtained for other purposes correlate with dual-energy x-ray absorptiometry (DXA) scores and compressive strengths.

Schreiber and associates evaluated 25 older patients who underwent an abdominal or lumbar CT scan and a lumbar spine DXA scan to determine whether HU correlated with BMD and T-scores. Control patients were identified from a list of patients with trauma to determine normative CT data. The mechanical properties of solid rigid polyurethane foam blocks were assessed with the use of a mechanical testing machine; all foam blocks were scanned with a CT scanner. Compressive strength values and HU were analyzed for correlation.

The HU value decreased relatively linearly by decade of life; the correlation between age and HU was significant. The correlations between the HU value and both BMD and T-score also were significant. In the polyurethane foam blocks, there was a perfect linear correlation between material density and the HU value.

The authors noted that the data have potential for fracture risk assessment, diagnosis of osteoporosis, and early initiation of needed treatment.