Journal of neuroimaging : official journal of the American Society of Neuroimaging
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The combination of phase demodulation and field mapping is a practical method to correct echo planar imaging (EPI) geometric distortion. However, since phase dispersion accumulates in each phase-encoding step, the calculation complexity of phase modulation is Ny-fold higher than conventional image reconstructions. Thus, correcting EPI images via phase demodulation is generally a time-consuming task. ⋯ GPU computing is a promising method to accelerate EPI geometric correction. The resulting reduction in computation time of phase demodulation should accelerate postprocessing for studies performed with EPI, and should effectuate the PROPELLER-EPI technique for clinical practice.
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Noncontrast computed tomography (NCCT) has been considered the standard test for determining eligibility for thrombolysis from the beginning of the thrombolytic era. CT angiography (CTA) reveals the cranio-cervical vessel and the occlusion site. Furthermore, the source image (SI) of the CTA (CTA-SI) reflects cerebral blood volume and can detect the infarct core as hypoattenuated areas with higher sensitivity than ischemic changes on NCCT. ⋯ On the other hand, CTA-SI using standardized protocol was reported to be good predictor for final infarct extension. Imaging used in the setting of acute stroke should accurately address the presence and size of an irreversible ischemic core. Further studies are required to confirm whether another measure or adjustment in CTA-SI values can be more reliable for evaluating the infarct core.
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Case Reports
Dramatic changes of a DWI lesion in a patient with acute ischemic stroke treated with IV t-PA.
A diffusion-weighted imaging (DWI) lesion changed dramatically in a hyperacute stroke case treated with intravenous tissue-plasminogen activator (IV t-PA). The initial hyperintense lesion on DWI disappeared completely immediately after IV t-PA treatment without improvement of neurological symptoms. However, the lesion reappeared 24 hours later. Successful thrombolysis can resolve DWI lesions but does not always improve the neurological symptoms.
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To describe a case of successful intracranial angioplasty and stenting of a symptomatic middle cerebral artery (MCA) stenosis using a transcervical approach. ⋯ Access of the intracranial circulation through direct CCA puncture may be a feasible alternative when the transfemoral access is not possible. The transcervical approach may be safe even with the use of antiplatelet medications and anticoagulation.
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Diffusion anisotropy color-coded maps of cerebral white matter can be generated from orthogonal anisotropic diffusion-weighted imaging (DWI) using the three-dimensional anisotropy contrast (3DAC) technique, but its precision has not been fully validated. Hence, we attempted to determine whether 3DAC is comparable to a diffusion tensor imaging (DTI) color map. ⋯ The 3DAC could visualize directional information of white matter tracts as precisely DTI-based color maps did, particularly when FA was large and/or e1 directions were orthogonal.