title: Signal intensity changes in T2-weighted MR image of the human trapezius muscle upon cold pressor stimulation.
abstract: OBJECTIVE
  The ability to measure hemodynamics of skeletal muscle proper is one of the major goals for muscle pain researchers. The aim of the present study was to evaluate the ability of signal intensity (SI) in T2-weighted trapezius muscle magnetic resonance imaging (MRI) to detect intramuscular hemodynamic changes during cold pressor stimulation (CPS).
  
  
  METHODS
  Fifteen healthy volunteers (mean age, 25.9+/-2.1 years) participated in this study. T2-weighted MRI was acquired using a 1.5 tesla MR unit with a body array coil. The slice level was set perpendicular to the muscle long axis at the mid-point of the horizontal portion of the right trapezius muscle. Cold pressor stimulation (4 degrees C) was applied to each subject's right foot and ankle for 2 min. The SI changes were recorded continuously for 7 min before, 2 min during, and 6 min after withdrawal of cold pressor stimulation. Six of these subjects also underwent a mock-CPS trial.
  
  
  RESULTS
  The mean SI level in T2-weighted trapezius muscle MRI significantly increased during CPS (P<0.0001, one way repeated measure ANOVA) and returned to the baseline level after cold pressor withdrawal. No statistically significant signal changes were observed across the mock-CPS trial subjects. These findings are identical to the cold pressor-induced hemodynamic changes documented in the trapezius muscle by near-infrared spectroscopy evaluation.
  
  
  CONCLUSIONS
  SI measurement in T2-weighted trapezius muscle MRI is sufficiently sensitive to detect intramuscular hemodynamic changes during CPS.
authors.affiliation: Department of Oral and Maxillofacial Rehabilitation, Okayama University Graduate School of Medicine and Dentistry, Okayama 700-8525, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Inoue-Minakuchi
authors.forename: T
authors.initials: T
authors.lastname: Kuboki
authors.forename: K
authors.initials: K
authors.lastname: Maekawa
authors.forename: Y
authors.initials: Y
authors.lastname: Yanagi
authors.forename: E
authors.initials: E
authors.lastname: Inoue
authors.forename: T
authors.initials: T
authors.lastname: Wakasa
authors.forename: K
authors.initials: K
authors.lastname: Kishi
authors.forename: H
authors.initials: H
authors.lastname: Yatani
authors.forename: G T
authors.initials: GT
authors.lastname: Clark
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000842:Ankle; D003080:Cold Temperature; D005528:Foot; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000502:physiology*; D010812:Physical Stimulation; D013997:Time Factors