title: Optimizing MR signal contrast of the temporomandibular joint disk.
abstract: OBJECTIVE
  To use a tissue specific algorithm to numerically optimize UTE sequence parameters to maximize contrast within temporomandibular joint (TMJ) donor tissue.
  
  
  METHODS
  A TMJ specimen tissue block was sectioned in a true sagittal plane and imaged at 3 Tesla (T) using UTE pulse sequences with dual echo subtraction. The MR tissue properties (PD, T(2) , T(2) *, and T(1) ) were measured and subsequently used to calculate the optimum sequences parameters (repetition time [TR], echo time [TE], and θ).
  
  
  RESULTS
  It was found that the main contrast available in the TMJ could be obtained from T(2) (or T(2) *) contrast. With the first echo time fixed at 8 μs and using TR = 200 ms, the optimum parameters were found to be: θ ≈ 60°, and TE2 ≈ 15 ms, when the second echo is acquired using a gradient echo and θ ≈ 120°, and TE2 ≈ 15 ms, when the second echo is acquired using a spin echo.
  
  
  CONCLUSIONS
  Our results show that MR signal contrast can be optimized between tissues in a systematic manner. The MR contrast within the TMJ was successfully optimized with facile delineation between disc and soft tissues.
authors.affiliation: GE Healthcare, San Diego, California, USA. michael.carl@ge.com
authors.forename: Michael
authors.initials: M
authors.lastname: Carl
authors.forename: Hatice T
authors.initials: HT
authors.lastname: Sanal
authors.forename: Eric
authors.initials: E
authors.lastname: Diaz
authors.forename: Jiang
authors.initials: J
authors.lastname: Du
authors.forename: Olivier
authors.initials: O
authors.lastname: Girard
authors.forename: Sheronda
authors.initials: S
authors.lastname: Statum
authors.forename: Richard
authors.initials: R
authors.lastname: Znamirowski
authors.forename: Christine B
authors.initials: CB
authors.lastname: Chung
mesh_terms: D000465:Algorithms; D002102:Cadaver; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D013704:Temporomandibular Joint / Q000033:anatomy & histology*