title: Pyrolytic graphite foam: a passive magnetic susceptibility matching material.
abstract: OBJECTIVE
  To evaluate a novel soft, lightweight cushion that can match the magnetic susceptibility of human tissue. The magnetic susceptibility difference between air and tissue produces field inhomogeneities in the B(0) field, which leads to susceptibility artifacts in magnetic resonance imaging (MRI) studies.
  
  
  METHODS
  Pyrolytic graphite (PG) microparticles were uniformly embedded into a foam cushion to reduce or eliminate field inhomogeneities at accessible air and tissue interfaces. 3T MR images and field maps of an air/water/PG foam phantom were acquired. Q measurements on a 4T tuned head coil and pulse sequence heating tests at 3T were also performed.
  
  
  RESULTS
  The PG foam improved susceptibility matching, reduced the field perturbations in phantoms, does not heat, and is nonconductive.
  
  
  CONCLUSIONS
  The susceptibility matched PG foam is lightweight, safe for patient use, adds no noise or MRI artifacts, is compatible with radiofrequency coil arrays, and improves B(0) homogeneity, which enables more robust MR studies.
authors.affiliation: Berkeley/UCSF Bioengineering Joint Graduate Group, University of California, Berkeley, California 94720, USA. glee@berkeley.edu
authors.forename: Gary C
authors.initials: GC
authors.lastname: Lee
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Goodwill
authors.forename: Kevin
authors.initials: K
authors.lastname: Phuong
authors.forename: Ben A
authors.initials: BA
authors.lastname: Inglis
authors.forename: Greig C
authors.initials: GC
authors.lastname: Scott
authors.forename: Brian A
authors.initials: BA
authors.lastname: Hargreaves
authors.forename: Lizabeth
authors.initials: L
authors.lastname: Li
authors.forename: Alex C
authors.initials: AC
authors.lastname: Chen
authors.forename: Rachana N
authors.initials: RN
authors.lastname: Shah
authors.forename: Steven M
authors.initials: SM
authors.lastname: Conolly
mesh_terms: D016477:Artifacts; D002244:Carbon / Q000737:chemistry*; D017352:Echo-Planar Imaging / Q000379:methods; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008422:Materials Testing; D008961:Models, Structural; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity; D055682:Viscoelastic Substances / Q000737:chemistry*
chemical_list: D055682:Viscoelastic Substances; C009139:pyrolytic carbon; D002244:Carbon
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