title: Quantitative assessment of the masseter muscle's elasticity using Acoustic Radiation Force Impulse.
abstract: OBJECTIVE
  The study proposes Acoustic Radiation Force Impulse (ARFI) assessment of the masseter muscle elasticity in the healthy population and in patients who have undergone head and neck radiation therapy.
  
  
  METHODS
  Twenty-five healthy controls constituted group A, and 13 patients who had underwent radiotherapy (35Gy minimum) formed group B. ARFI was performed bilaterally in the periphery (P) and the muscle center (C), in relaxation and contraction. Means and standard deviations were obtained for the recorded shear waves velocities (SWV).
  
  
  RESULTS
  For group A: in the relaxed right muscle C = 1.87±0.52 m/s and P = 1.96 ±0.55 m/s and in the left muscle C = 1.66 +/- 0.47 m/s, P = 1.67 +/-0.53 m/s. For group B, in relaxation, the right side presented C = 1.67 +/-0.6 m/s, P 1.72 +/-0.56 m/s, the left muscle C = 1.6 +/-0.34 m/s, P = 1.73 +/-0.37 m/s. There were no differences (p> 0.05) between P and C of both groups, regardless of the muscle state. The values for relaxation and contraction in A and B (merged values of the right and left) presented no differences (1.79+/-0.52 m/s vs 1.72 +/-0.73 m/s, p = 0.72 and 1.70 +/-0.48 m/s and vs 1.59 +/-0.77 m/s, p = 0.98). All measurements of group A vs B were not different (1.79 +/-0.52 m/s vs 1.65 +/-0.63 m/s, p = 0.78).
  
  
  CONCLUSIONS
  ARFI with SWV measurement enables the quantification of normal and post irradiation elasticity of the masseter. Further studies on a larger population are required to validate the normal and pathologic values.
authors.affiliation: Department of Conservative Odontology "Iuliu Haţieganu" University of Medicine and Pharmacy, Cluj Napoca, Romania. tamas-szora.attila@umfcluj.ro.
authors.forename: Iulia
authors.initials: I
authors.lastname: Badea
authors.affiliation: Imaging Department, "O. Fodor" Institute of Gastroenterology and Hepatology, "Iuliu Haţieganu" University of Medicine and Pharmacy, Cluj Napoca, Romania.
authors.forename: Attila
authors.initials: A
authors.lastname: Tamas-Szora
authors.affiliation: Faculty of Mathematics and Informatics, Department of Mathematics, Babes-Bolyai University Cluj Napoca Romania.
authors.forename: Ioana
authors.initials: I
authors.lastname: Chiorean
authors.affiliation: 4Departemnt of Maxilo-Facial Radiology "Iuliu Haţieganu" University of Medicine and Pharmacy, Cluj Napoca, Romania.
authors.forename: Floarea
authors.initials: F
authors.lastname: Fildan
authors.affiliation: Department of Radiotherapy Oncologic Institute ''Prof.dr. Ion Chiricuta''Cluj Napoca, Romania.
authors.forename: Elisabeta
authors.initials: E
authors.lastname: Ciulea
authors.affiliation: Department of Preventive Dentistry, "Iuliu Haţieganu" University of Medicine and Pharmacy, Cluj Napoca, Romania.
authors.forename: Mîndra
authors.initials: M
authors.lastname: Badea
mesh_terms: D000293:Adolescent; D000328:Adult; D001732:Bite Force; D004548:Elasticity / Q000502:physiology / Q000528:radiation effects; D054459:Elasticity Imaging Techniques / Q000379:methods* / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008406:Masseter Muscle / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000528:radiation effects; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology / Q000528:radiation effects; D009126:Muscle Relaxation / Q000502:physiology / Q000528:radiation effects; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy; D011446:Prospective Studies; D011832:Radiation Injuries / Q000000981:diagnostic imaging / Q000503:physiopathology; D011879:Radiotherapy Dosage; D012016:Reference Values; D055815:Young Adult