title: MR elastography of the head and neck: driver design and initial results.
abstract: OBJECTIVE
  The purpose was to describe the design and fabrication of a driver suitable for magnetic resonance elastography (MRE) of the head and neck and to assess its performance in evaluating human parotid gland, lymph nodes and thyroid at 3.0 T.
  
  
  METHODS
  A head and neck driver was fabricated using a commercial transducer, headrest mould and piston extension. Driver performance was tested using a motion-sensitized spin-echo MRE pulse sequence. Six healthy volunteers and three patients (two metastatic nodes and one papillary carcinoma) were evaluated using MRE. Viscoelastic maps were computed to obtain storage modulus (G') and loss modulus (G") of the normal parotid and thyroid, metastatic node and thyroid cancer. Reproducibility was assessed by coefficient of variation.
  
  
  RESULTS
  All subjects completed MRE examination without discomfort. Initial G' and G" values were as follows: normal parotid gland, 1.12 kPa and 0.48 kPa; thyroid, 0.58 kPa and 0.42 kPa; metastatic node, 0.66 kPa and 0.58 kPa; and thyroid cancer, 0.17 kPa and 0.28 kPa. Based on parotid data, the coefficient of variation for G' and G" was 4.7% and 9.8%.
  
  
  CONCLUSIONS
  A new MRE driver for head and neck was successfully implemented, and our initial results suggested the device was suitable for the mechanical assessment of tissues in the head and neck.
authors.affiliation: Department of Imaging and Interventional Radiology, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China. dkyeung@cuhk.edu.hk
authors.forename: David K W
authors.initials: DK
authors.lastname: Yeung
authors.forename: Kunwar S
authors.initials: KS
authors.lastname: Bhatia
authors.forename: Yolanda Y P
authors.initials: YY
authors.lastname: Lee
authors.forename: Ann D
authors.initials: AD
authors.lastname: King
authors.forename: Philippe
authors.initials: P
authors.lastname: Garteiser
authors.forename: Ralph
authors.initials: R
authors.lastname: Sinkus
authors.forename: Anil T
authors.initials: AT
authors.lastname: Ahuja
mesh_terms: D000328:Adult; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006258:Head and Neck Neoplasms / Q000473:pathology / Q000503:physiopathology* / Q000556:secondary*; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D014159:Transducers