## Abstract Diffusion‐weighted images acquired with the echo‐planar imaging technique are highly sensitive to eddy current induced geometric distortions that vary with the magnitude and direction of the diffusion sensitizing gradients. Such distortions cause misalignment of images acquired with dif
Geometric distortion correction of high-resolution 3 T diffusion tensor brain images
✍ Scribed by Siamak Ardekani; Usha Sinha
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 698 KB
- Volume
- 54
- Category
- Article
- ISSN
- 0740-3194
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Diffusion‐weighted images based on echo planar sequences suffer from distortions due to field inhomogeneities from susceptibility differences as well as from eddy currents arising from diffusion gradients. In this paper, a novel approach using nonlinear warping based on optic flow to correct distortions of baseline and diffusion weighted echo planar images (EPI) acquired at 3 T is presented. The distortion correction was estimated by warping the echo planar images to the anatomically correct T~2~‐weighted fast spin echo images (T2‐FSE). A global histogram intensity matching of the T2‐FSE precedes the base line EPI image distortion correction. A local intensity‐matching algorithm was used to transform labeled T2‐FSE regions to match intensities of diffusion‐weighted EPI images prior to distortion correction of these images. Evaluation was performed using three methods: (i) visual comparison of overlaid contours, (ii) a global mutual information index, and (iii) a local distance measure between homologous points. Visual assessment and the global index demonstrated a decrease in geometrical distortion and the distance measure showed that distortions are reduced to a subvoxel level. In conclusion, the warping algorithm is effective in reducing geometric distortions, enabling generation of anatomically correct diffusion tensor images at 3 T. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
📜 SIMILAR VOLUMES
## Abstract There is a need for an imaging sequence that can provide high‐resolution diffusion tensor images at 3T near air–tissue interfaces. By employing a radial fast spin‐echo (FSE) collection in conjunction with magnitude filtered back‐projection reconstruction, high‐resolution diffusion‐weigh
## Abstract The accuracy of fiber tracking on the basis of diffusion tensor magnetic resonance imaging (DTI) is affected by many parameters. To increase accuracy of the tracking algorithm, we introduce DTI with a fourth‐order tensor. Tensor elements comprise information obtained by high angular res
## Abstract ## Purpose To evaluate techniques for anatomical and physiological imaging of the intracranial optic nerve (ON), optic chiasm (OC), and optic tract (OT) at 3T with the aim of visualizing axonal damage in multiple sclerosis (MS). ## Materials and Methods Imaging was performed on a 3T
## Abstract A technique integrating multishot periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) and parallel imaging is presented for diffusion echo‐planar imaging (EPI) at high spatial resolution. The method combines the advantages of parallel imaging to achi