title: Imaging the shear modulus of the heel fat pads.
abstract: BACKGROUND
  Steady state, dynamic MR elastography provides quantitative images of the shear modulus of tissues in vivo. MR elastography was evaluated for its ability to characterize the mechanical properties of the weight bearing plantar soft tissues in vivo.
  
  
  METHODS
  MR elastography was used to image the heel fat pad and surrounding soft tissues when the subject applied a low pressure on the foot and again when the subject applied high pressure. The placement of the foot was identical for both sets of images.
  
  
  RESULTS
  The results agree well with expected trends. The shear modulus of the tissue under the calcaneus increased from 8 kPa to 12 kPa with increasing pressure while that of peripheral tissues remained constant at 8 kPa which is similar to the shear modulus of fat in breast tissue.
  
  
  CONCLUSIONS
  Preliminary results from the steady state MR elastography methods being developed to measure the shear modulus of plantar soft tissues are promising. MR elastography is sufficiently accurate to observe the change in shear modulus with changes in applied pressure and is capable of characterizing the mechanical properties of the plantar soft tissues. Detailed anatomic information can be combined with co-registered mechanical properties. MR elastography could play a significant role in understanding the weight bearing functions of the plantar soft tissues and in evaluating those structures for improved diagnosis and assessment of disease progression.
authors.affiliation: Department of Radiology, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03755, USA. john.b.weaver@hitchcock.org
authors.forename: John B
authors.initials: JB
authors.lastname: Weaver
authors.forename: Marvin
authors.initials: M
authors.lastname: Doyley
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Cheung
authors.forename: Francis
authors.initials: F
authors.lastname: Kennedy
authors.forename: Ernest L
authors.initials: EL
authors.lastname: Madsen
authors.forename: Elijah E W
authors.initials: EE
authors.lastname: Van Houten
authors.forename: Keith
authors.initials: K
authors.lastname: Paulsen
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology / Q000502:physiology*; D004548:Elasticity; D006365:Heel / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D010808:Physical Examination / Q000295:instrumentation / Q000379:methods*; D011312:Pressure; D033081:Shear Strength; D014732:Vibration; D016474:Weight-Bearing / Q000502:physiology*