Correction of b0-distortions in echo-planar-imaging-based perfusion-weighted mri

Abstract

Purpose To evaluate and quantify a scheme for correcting susceptibility artifacts in spin-echo echo-planar-imaging-based dynamic susceptibility contrast (DSC) perfusion MRI of high-grade gliomas at 3 Tesla. Materials and Methods Sixteen patients with a total of 78 scans were studied. DSC-MRI images were corrected using a displacement map generated from opposite phase-encoding polarity images. Two methods were used for quantification in the correction: (i) linear regression of pixel-by-pixel comparisons, performed both globally and relative to the anterior and posterior commissure plane (AC-PC plane), of T2-weighted images with both corrected and uncorrected raw DSC images; and (ii) counting significant (>2.0) normalized cerebral blood volume (nCBV) pixels from perfusion maps in the tumor region of interest. Results Sixty-four of 78 datasets showed significant differences in the coefficient of correlation (r2) values. The difference between corrected and uncorrected r 2 values was positive in all but one patient. Correction of B0- distortion significantly improved r2 in slices around the AC-PC plane. In 62% of the datasets, we observed an increased number of significant pixels in the corrected nCBV maps; 36% showed more significant pixels in uncorrected nCBV maps; 1% showed no difference. Conclusion Distortion correction of DSC-MRI may provide improved accuracy compared with uncorrected data, especially for tumors located below the corpus callosum and near the frontal sinuses. J. Magn. Reson. Imaging 2014;39:722-728. © 2013 Wiley Periodicals, Inc. Copyright © 2013 Wiley Periodicals, Inc.