title: Sensitivity of quantitative UTE MRI to the biomechanical property of the temporomandibular joint disc.
abstract: OBJECTIVE
  To quantify MR properties of discs from cadaveric human temporomandibular joints (TMJ) using quantitative conventional and ultrashort time-to-echo magnetic resonance imaging (UTE MRI) techniques and to corroborate regional variation in the MR properties with that of biomechanical indentation stiffness.
  
  
  METHODS
  This study was exempt from the institutional review board approval. Cadaveric (four donors, two females, 74 ± 10.7 years) TMJs were sliced (n = 14 slices total) sagittally and imaged using quantitative techniques of conventional spin echo T2 (SE T2), UTE T2*, and UTE T1rho. The discs were then subjected to biomechanical indentation testing, which is performed by compressing the tissue with the blunt end of a small solid cylinder. Regional variations in MR and indentation stiffness were correlated. TMJ of a healthy volunteer was also imaged to show in vivo feasibility.
  
  
  RESULTS
  Using the ME SE T2 and the UTE T1rho techniques, a significant (each p < 0.0001) inverse relation between MR and indentation stiffness properties was observed for the data in the lower range of stiffness. However, the strength of correlation was significantly higher (p < 0.05) for UTE T1rho (R(2) = 0.42) than SE T2 (R(2) = 0.19) or UTE T2* (R(2) = 0.02, p = 0.1) techniques.
  
  
  CONCLUSIONS
  The UTE T1rho technique, applicable in vivo, facilitated quantitative evaluation of TMJ discs and showed a high sensitivity to biomechanical softening of the TMJ discs. With additional work, the technique may become a useful surrogate measure for loss of biomechanical integrity of TMJ discs reflecting degeneration.
authors.affiliation: Department of Radiology, University of California-San Diego, 408 Dickinson St., San Diego, CA, 92103-8226, USA.
authors.forename: Won C
authors.initials: WC
authors.lastname: Bae
authors.forename: Reni
authors.initials: R
authors.lastname: Biswas
authors.forename: Sheronda
authors.initials: S
authors.lastname: Statum
authors.forename: Robert L
authors.initials: RL
authors.lastname: Sah
authors.forename: Christine B
authors.initials: CB
authors.lastname: Chung
mesh_terms: D000368:Aged; D000465:Algorithms; D002102:Cadaver; D019245:Compressive Strength / Q000502:physiology; D055119:Elastic Modulus / Q000502:physiology; D005260:Female; D006244:Hardness / Q000502:physiology; D006245:Hardness Tests; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D019224:Temporomandibular Joint Disc / Q000033:anatomy & histology* / Q000502:physiology*