Magnetic resonance spectroscopic imaging for visualization and correction of distortions in MRI: High precision applications in neurosurgery

We present a method for the quantification and correction of geometrical/in tensity distortions of magnetic resonance images predominantly caused by bu lk magnetic susceptibility shifts due to susceptibility heterogeneities of measured biologic tissues and shape of the object under investigation. The method includes precise and fast measurements of the static magnetic-held d istribution inside the measured object and automated data processing. Magne tic-field deviations in the range [-2.4; 2.6] ppm were found in the human b rain at B-0 = 1.5 T, For routinely used imaging parameters, with a read gra dient strength of about similar to 1 mT/m, the magnetic-held perturbations in the human brain can cause geometrical distortions up to +/-4 mm and inte nsity changes up to +/-50%, MR images corrected by the described method are suitable for planning high precision applications in neurosurgery. (C) 199 8 Elsevier Science Inc.