1. Reducing distortions in echo-planar breast imaging at ultrahigh field with high-resolution off-resonance maps
- Author
-
Peter R. Seevinck, Frank Zijlstra, Josien P. W. Pluim, Dennis W. J. Klomp, Michael J. van Rijssel, Kenneth G. A. Gilhuijs, Peter R. Luijten, and Medical Image Analysis
- Subjects
Adult ,Wilcoxon signed-rank test ,7T ,Swine ,Breast imaging ,Computer science ,diffusion-weighted imaging ,off-resonance ,SDG 3 – Goede gezondheid en welzijn ,Models, Biological ,Imaging phantom ,030218 nuclear medicine & medical imaging ,Full Papers—Computer Processing and Modeling ,distortion correction ,03 medical and health sciences ,0302 clinical medicine ,SDG 3 - Good Health and Well-being ,Off resonance ,off‐resonance ,Image Processing, Computer-Assisted ,medicine ,Animals ,Humans ,Breast MRI ,Radiology, Nuclear Medicine and imaging ,breast ,Full Paper ,medicine.diagnostic_test ,diffusion‐weighted imaging ,Phantoms, Imaging ,Distortion correction ,Middle Aged ,B mapping ,echo-planar imaging ,B0 mapping ,Female ,echo‐planar imaging ,Algorithms ,030217 neurology & neurosurgery ,Ex vivo ,Biomedical engineering ,Diffusion MRI - Abstract
Purpose: DWI is a promising modality in breast MRI, but its clinical acceptance is slow. Analysis of DWI is hampered by geometric distortion artifacts, which are caused by off-resonant spins in combination with the low phase-encoding bandwidth of the EPI sequence used. Existing correction methods assume smooth off-resonance fields, which we show to be invalid in the human breast, where high discontinuities arise at tissue interfaces. Methods: We developed a distortion correction method that incorporates high-resolution off-resonance maps to better solve for severe distortions at tissue interfaces. The method was evaluated quantitatively both ex vivo in a porcine tissue phantom and in vivo in 5 healthy volunteers. The added value of high-resolution off-resonance maps was tested using a Wilcoxon signed rank test comparing the quantitative results obtained with a low-resolution off-resonance map with those obtained with a high-resolution map. Results: Distortion correction using low-resolution off-resonance maps corrected most of the distortions, as expected. Still, all quantitative comparison metrics showed increased conformity between the corrected EPI images and a high-bandwidth reference scan for both the ex vivo and in vivo experiments. All metrics showed a significant improvement when a high-resolution off-resonance map was used (P < 0.05), in particular at tissue boundaries. Conclusion: The use of off-resonance maps of a resolution higher than EPI scans significantly improves upon existing distortion correction techniques, specifically by superior correction at glandular tissue boundaries.
- Published
- 2019