title: Magnetic resonance imaging of human mandibular elevator muscles after repetitive maximal clenching exercise.
abstract: Exercise can enhance the signal intensity (SI) of skeletal limb muscles on T2-weighted magnetic resonance imaging (MRI). The purpose here was to evaluate the effects of repetitive maximal clenching exercises involving the mandibular elevator muscles with T2-weighted MRI. Seven normal volunteers were imaged before and immediately after performing repetitive maximal clenching and at 3, 6, 9, 12, 15, 20 min after the exercise in a 1.5 T GE magnet with spin-echo sequences. SI in the masseter, medial pterygoid and temporalis increased significantly (p < 0.001) and the cross-sectional area (CSA) of masseter increased 10.11% on T2-weighted MRI after exercise. The increased SI and CSA declined approximately to the pre-exercise level in about 20 min after exercise. No SI and CSA changes were found in the inactive neck muscle and no SI changes in the mandibular bone marrow (p > 0.05). The findings suggest that the use of exercise-enhanced MRI might be helpful in the study of the function and dysfunction of muscles in the orofacial region.
authors.affiliation: Department of Oral Radiology, School of Stomatology, Beijing Medical University, People's Republic of China.
authors.forename: Y
authors.initials: Y
authors.lastname: Gan
authors.forename: T
authors.initials: T
authors.lastname: Sasai
authors.forename: H
authors.initials: H
authors.lastname: Nishiyama
authors.forename: X
authors.initials: X
authors.lastname: Ma
authors.forename: Z
authors.initials: Z
authors.lastname: Zhang
authors.forename: H
authors.initials: H
authors.lastname: Fuchihata
mesh_terms: D000328:Adult; D019412:Anatomy, Cross-Sectional; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008410:Masticatory Muscles / Q000033:anatomy & histology / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D009334:Neck Muscles / Q000502:physiology