Use of routine thoracic and abdominal computed tomography scans for assessing bone mineral density and detecting osteoporosis

Abstract

Objective:

Evaluation of computed tomography (CT) attenuation measurements for assessing bone mineral density (BMD) and predicting osteoporosis in thoracic and abdominal CT scans for various clinical indications using dual-energy X-ray absorptiometry (DXA) as reference standard.

Research design and methods:

A total of 234 patients (147 women, 87 men) undergoing DXA and CT were examined retrospectively. Mean time between both studies was 0.5 years. CT-attenuation values in Hounsfield units (HU) were measured at the thoracic and lumbar spine (T1, T6, T12, L1–L5), at the femoral neck, and then assigned to their corresponding DXA scores.

Results:

Patients with DXA-defined osteoporosis or osteopenia showed significantly lower HU values of trabecular bone at all measured levels compared to healthy subjects (p < 0.001). HU values were highest at T1 and T6, lowest at L1–L3 and the femoral neck. There were no significant intraindividual differences between HU values in the sagittal, coronal or transversal plane. Significant differences between normal and abnormal BMD categories were verified for three CT scanners. More than half of all fractures were detected in patients with non-osteoporotic DXA T-scores.

Conclusions:

Abdominal and particularly thoracic CT scans obtained for other clinical indications can sensibly be applied toward determining low BMD, detecting osteoporosis and identifying persons at increased fracture risk. Osteoporotic morbidity and mortality might be minimized. Superiorly to DXA, fragility fractures can be found without additional imaging or radiation exposure which can initiate early adequate treatment.

Limitations:

Key limitations of the study were as following: a retrospective, single-center study; small patient cohort – larger cohorts are needed to evaluate the sensitivity and specificity of diagnostic performance measurements; more complex CT evaluation of the hip for BMD assessment; DXA measurements were used as a reference standard, however, patients with unsuspected compression fractures but showing osteopenic or even normal BMD outline the limitations of DXA.

Keywords: :

• Bone mineral density
• CT scans
• DXA
• Fragility fractures
• Hounsfield units
• Osteoporosis

Transparency

Declaration of funding

There was no sponsorship/funding for this retrospective, single-center study.

Author contributions: All the authors have fulfilled ICMJE authorship criteria. M.M., B.E., H.H.S. and H.M.S. contributed to the conception and design; analysis and interpretation of the data; the drafting of the article and critical revision; they also gave final approval of the version to be published, and agreed to be accountable for all aspects of the work. K.W. contributed to the conception and design; analysis and interpretation of the data; agreed to be accountable for all aspects of the work. B.K. helped with the final approval of the version to be published, and agreed to be accountable for all aspects of the work.

Declaration of financial/other relationships

M.M., B.E., K.W., B.K., H.H.S., and H.M.S. have disclosed that they have no significant relationships with or financial interests in any commercial companies related to this study or article.

CMRO peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Acknowledgments

The authors acknowledge Olga Ramig, Department of Radiology, Hospital & Medical School, University of Bonn, Germany, for her skillful assistance and support in collecting data.