Journal of magnetic resonance imaging : JMRI
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J Magn Reson Imaging · Sep 2008
Complex threshold method for identifying pixels that contain predominantly noise in magnetic resonance images.
To create a robust means to remove noise pixels using complex data. ⋯ The joint use of both magnitude and phase images helps to improve the removal of noise points in magnetic resonance images. This can prove useful in automating the visualization of phase images without the highly distractive phase noise in noise regions. Also, it is useful in susceptibility weighted imaging when taking the minimum intensity projections of variably sized regions.
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To apply diffusion tensor images using 30 noncollinear directions for diffusion-weighted gradient schemes to characterize diffusion tensor imaging (DTI) features associated with C6 glioma-bearing rat brains, and ideally visualize fiber tractography datasets. ⋯ We have demonstrated in this study that fiber tractography with the 30 noncollinear diffusion gradient scheme method can be used to help provide a better understanding regarding the influence of a tumor on the surrounding regions of normal brain tissue in vivo.
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J Magn Reson Imaging · Sep 2008
Visualization of the protective ability of a free radical trapping compound against rat C6 and F98 gliomas with diffusion tensor fiber tractography.
To apply fiber tractography to assess the effect of a possible antiglioma drug, phenyl N-tert-butyl nitrone (PBN), on glioma-affected neuronal fibers. The fiber tractography method was able to differentiate between different tumor types, such as the C6 and F98 rat glioma models. ⋯ By noninvasively monitoring the degree of neuronal fiber integrity and connectivity with the use of neuronal fiber tractography, we were able to evaluate the protective effect of PBN against invasive glioma growth in rat brains. PBN provided protection of the neuronal fibers against tumor-induced ischemia and tumor invasion.
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J Magn Reson Imaging · Sep 2008
Fast projective carotid MR angiography using arterial spin-labeled balanced SSFP.
To determine whether pulsed arterial spin-labeled (pulsed ASL) balanced steady-state free precession (bSSFP) imaging allows for rapid projective depiction of the carotid arteries without electrocardiographic (ECG) gating. ⋯ pulsed ASL bSSFP is a fast technique for projective carotid angiography that may not require ECG gating. Acquisition time may be decreased with reduced FOV or parallel imaging strategies.
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J Magn Reson Imaging · Sep 2008
Investigation and optimization of parameter accuracy in dynamic contrast-enhanced MRI.
To present a modified pharmacokinetic model for improved parameter accuracy and to investigate the influence of an inaccurate arterial input function (AIF) on dynamic contrast-enhanced (DCE)-MRI parameter estimates of the transfer constant (Ktrans), blood volume (vp), and interstitial volume (ve). ⋯ While an accurate, high temporal resolution AIF is essential for estimating vp, a biexponential AIF acquired at low temporal resolution (<20 seconds) provides robust estimates of ve and results in a Ktrans underestimation comparable to that from a 25% error in the initial AIF bolus amplitude.