Andrea Toelly, Presenter: Nothing to Disclose

Constanze Bardach, Abstract Co-Author: Nothing to Disclose

Michael Weber, Abstract Co-Author: Nothing to Disclose

Rui Gong, Abstract Co-Author: Nothing to Disclose

Yanbo Lai, Abstract Co-Author: Nothing to Disclose

Pei Wang, Abstract Co-Author: Nothing to Disclose

Yulin Guo MD, Abstract Co-Author: Nothing to Disclose

Michael Gruber MD, Abstract Co-Author: Nothing to Disclose

To evaluate the correlation between bone mineral density (BMD) measurements on unenhanced, routine CT scans using a phantom-less measurement tool and the 10-year fracture probability calculated by the FRAX® tool. In addition, the ability to identify a potentially aggravated fracture risk using this measurement tool was investigated.

Seventy-seven postmenopausal women (mean age: 57.2 years), who underwent a routine, unenhanced CT scan, were included. The mean BMD value of each patient, including the Th12 – L4 vertebrae, was calculated retrospectively using a commercially available phantom-less measurement tool. Exclusion criteria were vertebral fractures, and sclerotic or osteolytic bone lesions. A minimum of two measurable vertebrae was required. In addition, the patient’s 10-year probability of a major osteoporotic fracture and of a hip fracture were calculated using the FRAX® tool without including DXA-BMD values.

Mean BMD values of patients with a 10-year probability of a major osteoporotic fracture ≥5% differed significantly compared to patients with a FRAX® score <5% (mean BMD value ≥5%: 59.13 mg/cm³; <5%: 83.32 mg/cm³; t=3,460, p=0.001). Phantom-less BMD measurements correlated significantly (p<0.001) with the fracture risk evaluated by FRAX® (Pearson correlation coefficient: major osteoporotic fracture risk R=-0.526, hip fracture risk R=-0.464). With a threshold of about 70 mg/cm³, the sensitivity was 75%, with a false-positive rate of 36.8%. However, with a threshold of about 80 mg/cm³ the sensitivity was 80% and the false-positive rate raised up to 50.9%. The intra-rater agreement of BMD measurements was calculated with an intraclass correlation (ICC) of 0.986, and the inter-observer reliability was calculated with an ICC of 0.987.

An increased fracture risk can be diagnosed as an additive finding on routine CT scans, without additional radiation exposure, by using a phantom-less tool. Patients with a decreased BMD value should be further evaluated using the FRAX® 10-year fracture probability calculation.

Patients with a decreased BMD value, measured with a phantom-less tool on routine CT scans, may benefit from an additional calculation of the FRAX® score to predict osteoporotic bone conditions.

Toelly, A, Bardach, C, Weber, M, Gong, R, Lai, Y, Wang, P, Guo, Y, Gruber, M, Correlation between BMD Measurements on Unenhanced Routine CT Scans Using a Phantom-less Measurement Tool and the 10-year Fracture Probability Calculated by FRAX®.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045539.html