## Abstract ## Purpose To quantify the changes in brain water diffusivity in hepatic encephalopathy (HE) associated with cirrhosis using diffusion tensor imaging (DTI) and to correlate with neuropsychological (NP) scores. ## Materials and Methods DTI was performed in 14 patients with low‐grade H
Phantom-based evaluation of geometric distortions in functional magnetic resonance and diffusion tensor imaging
✍ Scribed by Seppo Mattila; Ville Renvall; Jaana Hiltunen; Douglas Kirven; Raimo Sepponen; Riitta Hari; Antti Tarkiainen
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 573 KB
- Volume
- 57
- Category
- Article
- ISSN
- 0740-3194
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Phantom‐based evaluation of geometric distortions in functional MRI and diffusion tensor imaging (DTI) was investigated. An acrylic water‐filled phantom with a grid structure was designed and manufactured to provide accurate geometric information over the volume measured in human brain imaging. The grid structures were well detected in data acquired using a 3‐T MRI scanner with echo‐planar imaging (EPI) sequences commonly applied in functional MRI and DTI. A method for quantifying distortions in the phantom data was presented and applied for the images. The validity of the phantom for EPI was evaluated by quantitatively comparing the distortions present in and induced by the phantom and a human brain when imaged under identical conditions. The results suggest that the new phantom can reveal geometric distortions easily undermined by standard MRI phantoms. For example, prominent variability in the distortions was found as a function of the orientation of the diffusion‐sensitizing gradient. Possible future applications for this type of phantom include quality assurance and calibration of the hardware and software used in EPI‐based functional MRI and DTI. Magn Reson Med 57:754–763, 2007. © 2007 Wiley‐Liss, Inc.
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