title: Comprehensive Assessment of Osteoporosis and Bone Fragility with CT Colonography.
abstract: OBJECTIVE
  To evaluate the ability of additional analysis of computed tomographic (CT) colonography images to provide a comprehensive osteoporosis assessment.
  
  
  METHODS
  This Health Insurance Portability and Accountability Act-compliant study was approved by our institutional review board with a waiver of informed consent. Diagnosis of osteoporosis and assessment of fracture risk were compared between biomechanical CT analysis and dual-energy x-ray absorptiometry (DXA) in 136 women (age range, 43-92 years), each of whom underwent CT colonography and DXA within a 6-month period (between January 2008 and April 2010). Blinded to the DXA data, biomechanical CT analysis was retrospectively applied to CT images by using phantomless calibration and finite element analysis to measure bone mineral density and bone strength at the hip and spine. Regression, Bland-Altman, and reclassification analyses and paired t tests were used to compare results.
  
  
  RESULTS
  For bone mineral density T scores at the femoral neck, biomechanical CT analysis was highly correlated (R(2) = 0.84) with DXA, did not differ from DXA (P = .15, paired t test), and was able to identify osteoporosis (as defined by DXA), with 100% sensitivity in eight of eight patients (95% confidence interval [CI]: 67.6%, 100%) and 98.4% specificity in 126 of 128 patients (95% CI: 94.5%, 99.6%). Considering both the hip and spine, the classification of patients at high risk for fracture by biomechanical CT analysis--those with osteoporosis or "fragile bone strength"--agreed well against classifications for clinical osteoporosis by DXA (T score ≤-2.5 at the hip or spine), with 82.8% sensitivity in 24 of 29 patients (95% CI: 65.4%, 92.4%) and 85.7% specificity in 66 of 77 patients (95% CI: 76.2%, 91.8%).
  
  
  CONCLUSIONS
  Retrospective biomechanical CT analysis of CT colonography for colorectal cancer screening provides a comprehensive osteoporosis assessment without requiring changes in imaging protocols.
authors.affiliation: From the Department of Radiology (J.L.F., N.S.M.), Division of Endocrinology (S.K., B.L.C.), and Division of Gastroenterology and Hepatology (D.H.B.), Mayo Clinic, 200 1st Ave SW, Rochester, MN 55902; O.N. Diagnostics, Berkeley, Calif (D.L.K., D.C.L., T.M.K.); and Departments of Mechanical Engineering and Bioengineering, University of California-Berkeley, Berkeley, Calif (T.M.K.).
authors.forename: Jeff L
authors.initials: JL
authors.lastname: Fidler
authors.affiliation: From the Department of Radiology (J.L.F., N.S.M.), Division of Endocrinology (S.K., B.L.C.), and Division of Gastroenterology and Hepatology (D.H.B.), Mayo Clinic, 200 1st Ave SW, Rochester, MN 55902; O.N. Diagnostics, Berkeley, Calif (D.L.K., D.C.L., T.M.K.); and Departments of Mechanical Engineering and Bioengineering, University of California-Berkeley, Berkeley, Calif (T.M.K.).
authors.forename: Naveen S
authors.initials: NS
authors.lastname: Murthy
authors.affiliation: From the Department of Radiology (J.L.F., N.S.M.), Division of Endocrinology (S.K., B.L.C.), and Division of Gastroenterology and Hepatology (D.H.B.), Mayo Clinic, 200 1st Ave SW, Rochester, MN 55902; O.N. Diagnostics, Berkeley, Calif (D.L.K., D.C.L., T.M.K.); and Departments of Mechanical Engineering and Bioengineering, University of California-Berkeley, Berkeley, Calif (T.M.K.).
authors.forename: Sundeep
authors.initials: S
authors.lastname: Khosla
authors.affiliation: From the Department of Radiology (J.L.F., N.S.M.), Division of Endocrinology (S.K., B.L.C.), and Division of Gastroenterology and Hepatology (D.H.B.), Mayo Clinic, 200 1st Ave SW, Rochester, MN 55902; O.N. Diagnostics, Berkeley, Calif (D.L.K., D.C.L., T.M.K.); and Departments of Mechanical Engineering and Bioengineering, University of California-Berkeley, Berkeley, Calif (T.M.K.).
authors.forename: Bart L
authors.initials: BL
authors.lastname: Clarke
authors.affiliation: From the Department of Radiology (J.L.F., N.S.M.), Division of Endocrinology (S.K., B.L.C.), and Division of Gastroenterology and Hepatology (D.H.B.), Mayo Clinic, 200 1st Ave SW, Rochester, MN 55902; O.N. Diagnostics, Berkeley, Calif (D.L.K., D.C.L., T.M.K.); and Departments of Mechanical Engineering and Bioengineering, University of California-Berkeley, Berkeley, Calif (T.M.K.).
authors.forename: David H
authors.initials: DH
authors.lastname: Bruining
authors.affiliation: From the Department of Radiology (J.L.F., N.S.M.), Division of Endocrinology (S.K., B.L.C.), and Division of Gastroenterology and Hepatology (D.H.B.), Mayo Clinic, 200 1st Ave SW, Rochester, MN 55902; O.N. Diagnostics, Berkeley, Calif (D.L.K., D.C.L., T.M.K.); and Departments of Mechanical Engineering and Bioengineering, University of California-Berkeley, Berkeley, Calif (T.M.K.).
authors.forename: David L
authors.initials: DL
authors.lastname: Kopperdahl
authors.affiliation: From the Department of Radiology (J.L.F., N.S.M.), Division of Endocrinology (S.K., B.L.C.), and Division of Gastroenterology and Hepatology (D.H.B.), Mayo Clinic, 200 1st Ave SW, Rochester, MN 55902; O.N. Diagnostics, Berkeley, Calif (D.L.K., D.C.L., T.M.K.); and Departments of Mechanical Engineering and Bioengineering, University of California-Berkeley, Berkeley, Calif (T.M.K.).
authors.forename: David C
authors.initials: DC
authors.lastname: Lee
authors.affiliation: From the Department of Radiology (J.L.F., N.S.M.), Division of Endocrinology (S.K., B.L.C.), and Division of Gastroenterology and Hepatology (D.H.B.), Mayo Clinic, 200 1st Ave SW, Rochester, MN 55902; O.N. Diagnostics, Berkeley, Calif (D.L.K., D.C.L., T.M.K.); and Departments of Mechanical Engineering and Bioengineering, University of California-Berkeley, Berkeley, Calif (T.M.K.).
authors.forename: Tony M
authors.initials: TM
authors.lastname: Keaveny
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D015519:Bone Density; D023881:Colonography, Computed Tomographic / Q000379:methods*; D005260:Female; D005272:Femur Neck / Q000000981:diagnostic imaging*; D006801:Humans; D008875:Middle Aged; D010024:Osteoporosis / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013131:Spine / Q000000981:diagnostic imaging*