Journal of magnetic resonance imaging : JMRI
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J Magn Reson Imaging · Nov 2006
Correction of eddy-current distortions in diffusion tensor images using the known directions and strengths of diffusion gradients.
To correct eddy-current artifacts in diffusion tensor (DT) images without the need to obtain auxiliary scans for the sole purpose of correction. ⋯ The proposed algorithm can accurately correct eddy-current artifacts in DT images. Its principal advantages are that only images with comparable signals and contrasts are cross-correlated, and no additional scans are required.
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J Magn Reson Imaging · Nov 2006
Automated perfusion-weighted MRI using localized arterial input functions.
To investigate the utility of an automated perfusion-weighted MRI (PWI) method for estimating cerebral blood flow (CBF) based on localized arterial input functions (AIFs) as compared to the standard method of manual global AIF selection, which is prone to deconvolution errors due to the effects of delay and dispersion of the contrast bolus. ⋯ Automated CBF calculation using local AIFs is feasible and appears to produce more useful CBF maps.
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To improve the tag persistence throughout the whole cardiac cycle by providing a constant tag-contrast throughout all the cardiac phases when using balanced steady-state free precession (bSSFP) imaging. ⋯ The tag persistence was significantly improved when the proposed method was applied, with better Tag-CNR during the diastolic cardiac phase. The improved Tag-CNR will support automated tagging analysis and quantification methods.
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J Magn Reson Imaging · Nov 2006
Quantification of distal antral contractile motility in healthy human stomach with magnetic resonance imaging.
To quantify healthy postprandial: 1) propagation, periodicity, geometry, and percentage occlusion by distal antral contraction waves (ACWs); and 2) changes in ACW activity in relationship to gastric emptying (GE). ⋯ Our results indicate that ACWs are not imperative for emptying of liquids. This study provides a detailed quantitative reference for MRI inquiries into pharmacologically- and pathologically-altered gastric motility.
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J Magn Reson Imaging · Nov 2006
Clinical TrialDisplacement of the facial nerve course by vestibular schwannoma: preoperative visualization using diffusion tensor tractography.
To preoperatively visualize the course of the facial nerve, which is displaced by vestibular schwannoma, using diffusion tensor (DT) tractography, and to evaluate the agreement with surgical findings. ⋯ Tractographs constructed using MR tensor images enabled us to identify tracts considered to represent facial nerves. We consider DT tractography to be a useful tool for preoperatively predicting facial nerve displacement in vestibular schwannoma.