Pyrolytic graphite foam: a passive magnetic susceptibility matching material.
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.
Lee
Gary C
GC
Berkeley/UCSF Bioengineering Joint Graduate Group, University of California, Berkeley, California 94720, USA. glee@berkeley.edu
Goodwill
Patrick W
PW
Phuong
Kevin
K
Inglis
Ben A
BA
Scott
Greig C
GC
Hargreaves
Brian A
BA
Li
Lizabeth
L
Chen
Alex C
AC
Shah
Rachana N
RN
Conolly
Steven M
SM
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*
D055682:Viscoelastic Substances; C009139:pyrolytic carbon; D002244:Carbon
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