Electricity: measuring and testing – Particle precession resonance – Using a nuclear resonance spectrometer system
Patent
1993-10-12
1994-09-27
Arana, Louis
Electricity: measuring and testing
Particle precession resonance
Using a nuclear resonance spectrometer system
324307, G01V 300
Patent
active
053510062
ABSTRACT:
An in-vivo correction method for the non-linear, shape dependent spatial distortion in MR images due to magnetic field inhomogeneity including inhomogeneity due to susceptibility variations is disclosed. Geometric distortion at the air/tissue and tissue/bone interfaces before and after the correction is quantified using a phantom. The results are also compared to the "distortion-free" CT images of the same phantom. Magnetic susceptibility of cortical cattle bone was measured using a SQUID magnetometer and found to be -8.86 ppm which is quite similar to that of tissue (-9 ppm). The distortion at the bone/tissue boundary was negligible while that at the air/tissue boundary created displacements of about 2.0 mm with a1.5T main magnetic field and a 3.13 mT/m gradient field, a significant value if MR images are used to localize targets with the high accuracy expected for stereotaxic surgery. The correction method reduces the errors to at least the same level of accuracy as CT.
REFERENCES:
patent: 4823085 (1989-04-01), Fuderer et al.
patent: 4876509 (1989-10-01), Perlmutter
"Geometrical Image Transformation to Compensate for MRI Distortions" by Chang et al. SPIE vol. 1233 Med. Imaging IV (1990) (month of pub. unknown).
"Total Inhomogeneity Correction Including Chem. Shifts and Susceptibility by View Angle Tilting" Med. Physics vol. 15 No. 1 Jan. 1988, Cho, Z. H. et al.
"MR Susceptibility Distortion Quantification and Correction for Steroetaoxy" by Sunumaweera et al. Proc. SPIE/SPSE Feb. 9-14, 1992.
Adler John R.
Glover Gary H.
Sumanaweera Thilaka S.
Arana Louis
Board of Trustees of the Leland Stanford Junior University
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