title: Clinical significance of magnetization transfer contrast imaging for edematous changes in masticatory muscle.
abstract: OBJECTIVE
  To evaluate inflammatory changes in masticatory muscles by magnetization transfer contrast (MTC) imaging.
  
  
  METHODS
  Gradient-recalled echo (GRE) and MTC-GRE images of relaxed masticatory muscles in 28 healthy volunteers were obtained before and after exercise. At the same time, muscle stiffness and pain in the masseter muscles were also measured. Magnetization transfer ratios (MTRs) of the muscles were calculated from the GRE and MTC-GRE images. The MTRs of the masticatory muscles in 50 patients with temporomandibular disorder were compared with those in the volunteers.
  
  
  RESULTS
  Immediately after the exercise, the MTRs of the masseter muscles significantly decreased (P < 0.05), whereas muscle stiffness and pain increased in the healthy volunteers. In patients with masseter muscle pain, the MTRs of the masseter muscles were significantly lower than in the healthy volunteers (P < 0.05).
  
  
  CONCLUSIONS
  Magnetization transfer contrast imaging strongly reflects the masticatory muscle edematous changes, possibly leading to masseter muscle pain.
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Kagoshima University, Kagoshima, Japan.
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Nagayama
authors.forename: Shigeaki
authors.initials: S
authors.lastname: Suenaga
authors.forename: Junko
authors.initials: J
authors.lastname: Nagata
authors.forename: Hiroko
authors.initials: H
authors.lastname: Takada
authors.forename: Hideyuki J
authors.initials: HJ
authors.lastname: Majima
authors.forename: Shouichi
authors.initials: S
authors.lastname: Miyawaki
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004487:Edema / Q000503:physiopathology*; D004576:Electromyography; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008410:Masticatory Muscles / Q000503:physiopathology*; D008875:Middle Aged; D010147:Pain Measurement; D018709:Statistics, Nonparametric