title: Quantifying temperature-dependent T1 changes in cortical bone using ultrashort echo-time MRI.
abstract: OBJECTIVE
  To demonstrate the feasibility of using ultrashort echo-time MRI to quantify T1 changes in cortical bone due to heating.
  
  
  METHODS
  Variable flip-angle T1 mapping combined with 3D ultrashort echo-time imaging was used to measure T1 in cortical bone. A calibration experiment was performed to detect T1 changes with temperature in ex vivo cortical bone samples from a bovine femur. Ultrasound heating experiments were performed using an interstitial applicator in ex vivo bovine femur specimens, and heat-induced T1 changes were quantified.
  
  
  RESULTS
  The calibration experiment demonstrated that T1 increases with temperature in cortical bone. We observed a linear relationship between temperature and T1 with a linear coefficient between 0.67 and 0.84 ms/°C over a range of 25-70°C. The ultrasound heating experiments showed increased T1 changes in the heated regions, and the relationship between the temperature changes and T1 changes was similar to that of the calibration.
  
  
  CONCLUSIONS
  We demonstrated a temperature dependence of T1 in ex vivo cortical bone using a variable flip-angle ultrashort echo-time T1 mapping method.
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Misung
authors.identifier: http://orcid.org/0000-0003-0918-8831
authors.initials: M
authors.lastname: Han
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Viola
authors.initials: V
authors.lastname: Rieke
authors.affiliation: Department of Radiation Oncology, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Serena J
authors.initials: SJ
authors.lastname: Scott
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Eugene
authors.initials: E
authors.lastname: Ozhinsky
authors.affiliation: Department of Radiation Oncology, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Vasant A
authors.initials: VA
authors.lastname: Salgaonkar
authors.affiliation: Department of Radiation Oncology, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Peter D
authors.initials: PD
authors.lastname: Jones
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA.|Joint Graduate Program in Bioengineering, University of California San Francisco/Berkeley, San Francisco, California, USA.
authors.forename: Peder E Z
authors.initials: PE
authors.lastname: Larson
authors.affiliation: Department of Radiation Oncology, University of California, San Francisco, San Francisco, California, USA.|Joint Graduate Program in Bioengineering, University of California San Francisco/Berkeley, San Francisco, California, USA.
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Diederich
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Roland
authors.initials: R
authors.lastname: Krug
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000502:physiology* / Q000528:radiation effects; D002417:Cattle; D005240:Feasibility Studies; D005269:Femur / Q000502:physiology* / Q000528:radiation effects; D006361:Heating / Q000379:methods; D019220:High-Energy Shock Waves; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013817:Thermography / Q000379:methods*
keywords: MR temperature mapping; T1 mapping; UTE imaging; cortical bone