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Correction of B0-distortions in echo-planar-imaging-based perfusion-weighted MRI
Jonas Vardal1, Raimo A Salo, Christopher Larsson
1Oslo University Hospital, Rikshospitalet, The Intervention Centre, Oslo, Norway; University of Oslo, Faculty of Medicine, Oslo, Norway.
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 r2 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.
Insights
Susceptibility artifact correction in dynamic susceptibility contrast (DSC) MRI improves accuracy for high-grade gliomas. This method enhances image quality, particularly for tumors near the brain
Area of Science:
- Neuroimaging
- Radiology
- Medical Physics
Background:
- Susceptibility artifacts in echo-planar imaging (EPI) can compromise the accuracy of dynamic susceptibility contrast (DSC) perfusion MRI.
- High-grade gliomas present diagnostic and therapeutic challenges, necessitating precise perfusion assessment.
Purpose of the Study:
- To evaluate and quantify a novel scheme for correcting susceptibility artifacts in DSC perfusion MRI of high-grade gliomas at 3 Tesla.
- To assess the impact of distortion correction on image analysis and diagnostic accuracy.
Main Methods:
- A displacement map generated from opposite phase-encoding polarity images was used for DSC-MRI correction.
- Quantification involved linear regression of T2-weighted and DSC images and counting significant normalized cerebral blood volume (nCBV) pixels within tumor regions of interest.
Main Results:
- Sixty-four out of 78 datasets demonstrated significant differences in correlation coefficients (r2) after correction.
- Distortion correction significantly improved r2 values, especially in slices near the anterior-posterior commissure (AC-PC) plane.
- Corrected nCBV maps showed an increased number of significant pixels in 62% of datasets.
Conclusions:
- Distortion correction enhances the accuracy of DSC-MRI for high-grade gliomas.
- The proposed correction scheme is particularly beneficial for tumors situated below the corpus callosum and near the frontal sinuses.
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