title: Finite element analysis applied to 3-T MR imaging of proximal femur microarchitecture: lower bone strength in patients with fragility fractures compared with control subjects.
abstract: OBJECTIVE
  To determine the feasibility of using finite element analysis applied to 3-T magnetic resonance (MR) images of proximal femur microarchitecture for detection of lower bone strength in subjects with fragility fractures compared with control subjects without fractures.
  
  
  METHODS
  This prospective study was institutional review board approved and HIPAA compliant. Written informed consent was obtained. Postmenopausal women with (n = 22) and without (n = 22) fragility fractures were matched for age and body mass index. All subjects underwent standard dual-energy x-ray absorptiometry. Images of proximal femur microarchitecture were obtained by using a high-spatial-resolution three-dimensional fast low-angle shot sequence at 3 T. Finite element analysis was applied to compute elastic modulus as a measure of strength in the femoral head and neck, Ward triangle, greater trochanter, and intertrochanteric region. The Mann-Whitney test was used to compare bone mineral density T scores and elastic moduli between the groups. The relationship (R(2)) between elastic moduli and bone mineral density T scores was assessed.
  
  
  RESULTS
  Patients with fractures showed lower elastic modulus than did control subjects in all proximal femur regions (femoral head, 8.51-8.73 GPa vs 9.32-9.67 GPa; P = .04; femoral neck, 3.11-3.72 GPa vs 4.39-4.82 GPa; P = .04; Ward triangle, 1.85-2.21 GPa vs 3.98-4.13 GPa; P = .04; intertrochanteric region, 1.62-2.18 GPa vs 3.86-4.47 GPa; P = .006-.007; greater trochanter, 0.65-1.21 GPa vs 1.96-2.62 GPa; P = .01-.02), but no differences in bone mineral density T scores. There were weak relationships between elastic moduli and bone mineral density T scores in patients with fractures (R(2) = 0.25-0.31, P = .02-.04), but not in control subjects. CONCLUSION Finite element analysis applied to high-spatial-resolution 3-T MR images of proximal femur microarchitecture can allow detection of lower elastic modulus, a marker of bone strength, in subjects with fragility fractures compared with control subjects. MR assessment of proximal femur strength may provide information about bone quality that is not provided by dual-energy x-ray absorptiometry.
authors.affiliation: From the Department of Radiology, Center for Musculoskeletal Care (G.C.), Osteoporosis Center, Hospital for Joint Diseases (S.H.), Department of Orthopaedic Surgery, Hospital for Joint Diseases (K.A.E.), and Department of Radiology, Center for Biomedical Imaging (G.C., R.B., C.M.D., J.S.B., R.R.R.), NYU Langone Medical Center, 550 First Avenue, New York, NY 10016; and Department of Radiology, University of Pennsylvania School of Medicine, 3400 Spruce Street, Philadelphia, PA (C.S.R.).
authors.forename: Gregory
authors.initials: G
authors.lastname: Chang
authors.forename: Stephen
authors.initials: S
authors.lastname: Honig
authors.forename: Ryan
authors.initials: R
authors.lastname: Brown
authors.forename: Cem M
authors.initials: CM
authors.lastname: Deniz
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Egol
authors.forename: James S
authors.initials: JS
authors.lastname: Babb
authors.forename: Ravinder R
authors.initials: RR
authors.lastname: Regatte
authors.forename: Chamith S
authors.initials: CS
authors.lastname: Rajapakse
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D015519:Bone Density; D016022:Case-Control Studies; D005240:Feasibility Studies; D005260:Female; D005269:Femur / Q000473:pathology* / Q000648:ultrastructure; D020342:Finite Element Analysis; D050723:Fractures, Bone / Q000209:etiology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000150:complications*; D011446:Prospective Studies; D012680:Sensitivity and Specificity