Jeff L. Fidler MD, Presenter: Research Grant, O.N. Diagnostics, LLC

Tony Keaveny, Abstract Co-Author: Stockholder, O.N. Diagnostics, LLC Consultant, O.N. Diagnostics, LLC

Naveen Srinivasa Murthy MD, Abstract Co-Author: Nothing to Disclose

David Lee, Abstract Co-Author: Employee, O.N. Diagnostics, LLC

Sundeep Khosla MD, Abstract Co-Author: Nothing to Disclose

Bart Clarke, Abstract Co-Author: Nothing to Disclose

David Bruining MD, Abstract Co-Author: Research Grant, Johnson & Johnson

David Kopperdahl, Abstract Co-Author: Employee, O.N. Diagnostics, LLC

To evaluate the utility of bone strength and density assessment at the hip using clinical CT colonography (CTC) scans, treating dual-energy x-ray absorptiometry (DXA) as a reference standard.

151 adults (136 women, 15 men; mean age, 69.0 years) underwent screening CTC and central (hip and spine) DXA bone mineral density (BMD) measurement within ± 167 days (mean interval, 8.7 days). BMD (in g/cm2) at the femoral neck— the preferred anatomic site in the WHO-recommended FRAX calculator for fracture risk assessment — and the associated T-score were compared as measured by DXA vs. supine CTC (with phantomless calibration). Femoral strength, simulating a sideways fall to the hip, was also assessed from the CTC scans using non-linear finite element analysis. Five different DXA Lunar scanners (3 Prodigy, 2 iDXA) and four different CT machines (2 GE, 2 Siemens) were used. All analyses of the CTC exams (VirtuOst 1.1.5, O.N. Diagnostics, Berkeley, CA) were performed blinded to the DXA data.

The DXA- and CTC-generated values of femoral neck BMD (for the left hip) were highly correlated (R=0.91), the degree of correlation equaling that between left hip vs. right hip values of BMD as measured solely by DXA (R=0.91). On average, femoral neck BMD as measured by CTC was higher compared to DXA by 0.026 g/cm2 (p<0.0001, paired t-test), which is comparable to between-manufacturer differences observed by others for DXA. The same number of patients (n=11) was classified as being osteoporotic (T ≤ -2.5) for both CTC and DXA. Of the eight patients with clinically relevant low levels of femoral strength (< 2700 N) as estimated by finite element analysis, four of those patients were classified by DXA as being osteoporotic (T ≤ -2.5) and four as osteopenic (-2.5 < T < -1.0).

Analysis of CTC scans provides hip BMD scores and T-score classifications of osteoporosis that are comparable to those obtained from DXA, and can further identify a subset of osteopenic patients with clinically relevant low levels of femoral strength. As such, CTC scans can provide a comprehensive osteoporosis fracture risk assessment for the hip.

Ancillary analysis of CTC exams can provide a comprehensive osteoporosis assessment for the hip, providing both DXA-equivalent BMD measures and estimates of femoral strength.

Fidler, J, Keaveny, T, Murthy, N, Lee, D, Khosla, S, Clarke, B, Bruining, D, Kopperdahl, D, Comprehensive Osteoporosis Assessment for the Hip using Ancillary CTC.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12031169.html