Journal of magnetic resonance imaging : JMRI
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J Magn Reson Imaging · Jan 2008
Effects of doubling and tripling the spatial resolution in standard 3D contrast-enhanced magnetic resonance angiography of carotid artery disease.
To determine whether three-dimensional (3D) contrast-enhanced MR angiography (CE-MRA) of carotid artery disease may be more effective when performed at double or triple the spatial resolution of the present common clinical standard at 1.5T. ⋯ In patients with carotid artery stenosis, decreasing the voxel volume to 0.5 mm(3) by increasing the scan time from 21 to 40 seconds resulted in sharper depiction of the carotid stenosis. Further decreases in voxel volume, by extending the acquisition time further, did not improve the vessel depiction due to both signal-to-noise ratio (SNR) and sharpness losses.
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J Magn Reson Imaging · Jan 2008
Randomized Controlled TrialRapid multiplanar abdominal survey using MRI with the steady-state free-precession technique.
To retrospectively evaluate the sensitivity, specificity, and positive and negative predictive values of steady-state free-precession (SSFP) survey MRI of the abdomen. ⋯ SSFP provides a rapid survey of the abdomen, with good sensitivity and few false positives.
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To develop a voxel-based analysis of an R2* map of healthy human brain that is automatic, reproducible, and realizable in a single examination on a 3T MR imager. Such a tool could be useful to measure iron accumulation in neurodegenerative diseases. ⋯ Our method, combining data acquisition and data processing, demonstrates the feasibility of voxel-based analysis on an R2* map and affords a high degree of sensitivity and good reproducibility while maintaining high spatial resolution.
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J Magn Reson Imaging · Dec 2007
Multiparametric differentiation of posterior fossa tumors in children using diffusion-weighted imaging and short echo-time 1H-MR spectroscopy.
To assess the combined value of diffusion-weighted imaging (DWI) and proton magnetic resonance spectroscopy (1H-MRS) in differentiating medulloblastoma, ependymoma, pilocytic astrocytoma, and infiltrating glioma in a pediatric population. ⋯ Linear discriminant analysis using DWI and MRS using water as internal reference, fully discriminates the four most frequent posterior fossa tumors in children.
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J Magn Reson Imaging · Dec 2007
Detecting groups of coherent voxels in functional MRI data using spectral analysis and replicator dynamics.
To investigate the relationship between functional MRI (fMRI) time series in the human brain, combining fMRI spectral analysis and replicator dynamics. ⋯ The application of replicator dynamics to spectral matrices is a reliable method for detecting groups of maximally coherent voxels. A replicator process is able to determine groups of voxels with the property that each voxel in the group exhibits a high coherence with every other group member. In contrast to the NCV approach, this method is parameter-free and does not require the a priori selection of a reference voxel.