title: Bone quantitative susceptibility mapping using a chemical species-specific R2* signal model with ultrashort and conventional echo data.
abstract: OBJECTIVE
  To develop quantitative susceptibility mapping (QSM) of bone using an ultrashort echo time (UTE) gradient echo (GRE) sequence for signal acquisition and a bone-specific effective transverse relaxation rate ( R2*) to model water-fat MR signals for field mapping.
  
  
  METHODS
  Three-dimensional radial UTE data (echo times ≥ 40 μs) was acquired on a 3 Tesla scanner and fitted with a bone-specific signal model to map the chemical species and susceptibility field. Experiments were performed ex vivo on a porcine hoof and in vivo on healthy human subjects (n = 7). For water-fat separation, a bone-specific model assigning R2* decay mostly to water was compared with the standard models that assigned the same decay for both fat and water. In the ex vivo experiment, bone QSM was correlated with CT.
  
  
  RESULTS
  Compared with standard models, the bone-specific R2* method significantly reduced errors in the fat fraction within the cortical bone in all tested data sets, leading to reduced artifacts in QSM. Good correlation was found between bone CT and QSM values in the porcine hoof (R2= 0.77). Bone QSM was successfully generated in all subjects.
  
  
  CONCLUSIONS
  The QSM of bone is feasible using UTE with a conventional echo time GRE acquisition and a bone-specific R2* signal model. Magn Reson Med 79:121-128, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA.|Department of Radiology, Weill Medical College of Cornell University, New York, New York, USA.
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Dimov
authors.affiliation: Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA.|Department of Radiology, Weill Medical College of Cornell University, New York, New York, USA.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Radiology, Weill Medical College of Cornell University, New York, New York, USA.
authors.forename: Pascal
authors.initials: P
authors.lastname: Spincemaille
authors.affiliation: Department of Radiology, Weill Medical College of Cornell University, New York, New York, USA.
authors.forename: Martin R
authors.initials: MR
authors.lastname: Prince
authors.affiliation: Department of Radiology, University of California, San Diego, California, USA.
authors.forename: Jiang
authors.initials: J
authors.lastname: Du
authors.affiliation: Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA.|Department of Radiology, Weill Medical College of Cornell University, New York, New York, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000328:Adult; D000465:Algorithms; D000818:Animals; D016477:Artifacts; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging; D064368:Healthy Volunteers; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008280:Magnetics; D008297:Male; D015233:Models, Statistical; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity; D013552:Swine; D014057:Tomography, X-Ray Computed; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water
keywords: bone imaging; quantitative susceptibility mapping (QSM); ultrashort echo time (UTE); water-fat separation