title: Dual inversion recovery ultrashort echo time (DIR-UTE) imaging and quantification of the zone of calcified cartilage (ZCC).
abstract: OBJECTIVE
  To develop ultrashort echo time (UTE) magnetic resonance imaging (MRI) techniques to image the zone of calcified cartilage (ZCC), and quantify its T2*, T1 and T1ρ.
  
  
  METHODS
  In this feasibility study a dual inversion recovery UTE (DIR-UTE) sequence was developed for high contrast imaging of the ZCC. T2* of the ZCC was measured with DIR-UTE acquisitions at progressively increasing TEs. T1 of the ZCC was measured with saturation recovery UTE acquisitions at progressively increasing saturation recovery times. T1ρ of the ZCC was measured with spin-locking prepared DIR-UTE acquisitions at progressively increasing spin-locking times.
  
  
  RESULTS
  The feasibility of the qualitative and quantitative DIR-UTE techniques was demonstrated on phantoms and in six cadaveric patellae using a clinical 3 T scanner. On average the ZCC has a short T2* ranging from 1.0 to 3.3 ms (mean ± standard deviation = 2.0 ± 1.2 ms), a short T1 ranging from 256 to 389 ms (mean ± standard deviation = 305 ± 45 ms), and a short T1ρ ranging from 2.2 to 4.6 ms (mean ± standard deviation = 3.6 ± 1.2 ms).
  
  
  CONCLUSIONS
  UTE MR based techniques have been developed for high resolution imaging of the ZCC and quantitative evaluation of its T2*, T1 and T1ρ relaxation times, providing non-invasive assessment of collagen orientation and proteoglycan content at the ZCC and the bone cartilage interface. These measurements may be useful for non-invasive assessment of the ZCC, including understanding the involvement of this tissue component in osteoarthritis.
authors.affiliation: Department of Radiology, University of California, San Diego, CA 92103-8756, United States. jiangdu@ucsd.edu
authors.forename: J
authors.initials: J
authors.lastname: Du
authors.forename: M
authors.initials: M
authors.lastname: Carl
authors.forename: W C
authors.initials: WC
authors.lastname: Bae
authors.forename: S
authors.initials: S
authors.lastname: Statum
authors.forename: E Y
authors.initials: EY
authors.lastname: Chang
authors.forename: G M
authors.initials: GM
authors.lastname: Bydder
authors.forename: C B
authors.initials: CB
authors.lastname: Chung
mesh_terms: D002102:Cadaver; D002113:Calcification, Physiologic / Q000502:physiology*; D002358:Cartilage, Articular / Q000502:physiology*; D005240:Feasibility Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D010329:Patella / Q000502:physiology*; D019047:Phantoms, Imaging; D059629:Signal-To-Noise Ratio