AJNR. American journal of neuroradiology
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AJNR Am J Neuroradiol · Jul 2014
Diffusion-weighted imaging with dual-echo echo-planar imaging for better sensitivity to acute stroke.
Parallel imaging facilitates the acquisition of echo-planar images with a reduced TE, enabling the incorporation of an additional image at a later TE. Here we investigated the use of a parallel imaging-enhanced dual-echo EPI sequence to improve lesion conspicuity in diffusion-weighted imaging. ⋯ Parallel imaging-enhanced dual-echo diffusion-weighted EPI is a useful method for evaluating lesions with reduced diffusivity. The long TE of echo 2 produced DWIs that exhibited superior lesion conspicuity compared with images acquired at a shorter TE. Echo 1 provided higher SNR ADC maps for specificity to acute infarction. The relaxivity maps may serve to complement information regarding blood products and mineralization.
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AJNR Am J Neuroradiol · Jul 2014
Rupture-associated changes of cerebral aneurysm geometry: high-resolution 3D imaging before and after rupture.
Comparisons of geometric data of ruptured and unruptured aneurysms may yield risk factors for rupture. Data on changes of geometric measures associated with rupture are, however, sparse, because patients with ruptured aneurysms rarely have undergone previous imaging of the intracranial vasculature. We had the opportunity to assess 3D geometric differences of aneurysms before and after rupture. The purpose of this study was to evaluate possible differences between prerupture and postrupture imaging of a ruptured intracranial aneurysm. ⋯ Geometric comparisons of aneurysms before and after rupture show a large volume increase, origination of lobulations, and displacement due to perianeurysmal hematoma. Geometric and hemodynamic comparison of series of unruptured and ruptured aneurysms in the search for rupture-risk-related factors should be interpreted with caution.
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AJNR Am J Neuroradiol · Jul 2014
ReviewHigh WSS or low WSS? Complex interactions of hemodynamics with intracranial aneurysm initiation, growth, and rupture: toward a unifying hypothesis.
Increasing detection of unruptured intracranial aneurysms, catastrophic outcomes from subarachnoid hemorrhage, and risks and cost of treatment necessitate defining objective predictive parameters of aneurysm rupture risk. Image-based computational fluid dynamics models have suggested associations between hemodynamics and intracranial aneurysm rupture, albeit with conflicting findings regarding wall shear stress. ⋯ Low wall shear stress and high oscillatory shear index trigger an inflammatory-cell-mediated pathway, which could be associated with the growth and rupture of large, atherosclerotic aneurysm phenotypes, while high wall shear stress combined with a positive wall shear stress gradient trigger a mural-cell-mediated pathway, which could be associated with the growth and rupture of small or secondary bleb aneurysm phenotypes. This hypothesis correlates disparate intracranial aneurysm pathophysiology with the results of computational fluid dynamics in search of more reliable risk predictors.
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AJNR Am J Neuroradiol · Jul 2014
Multicenter StudyPerfusion-based selection for endovascular reperfusion therapy in anterior circulation acute ischemic stroke.
Controversy exists about the role of perfusion imaging in patient selection for endovascular reperfusion therapy in acute ischemic stroke. We hypothesized that perfusion imaging versus noncontrast CT- based selection would be associated with improved functional outcomes at 3 months. ⋯ In this multicenter study, patients with acute ischemic stroke who underwent perfusion imaging were more than 2-fold more likely to have good outcomes following endovascular reperfusion therapy. Randomized studies should compare perfusion imaging with NCCT imaging for patient selection for endovascular reperfusion therapy.
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AJNR Am J Neuroradiol · Jul 2014
Identification of the inflow zone of unruptured cerebral aneurysms: comparison of 4D flow MRI and 3D TOF MRA data.
The hemodynamics of the inflow zone of cerebral aneurysms may be a key factor in coil compaction and recanalization after endovascular coil embolization. We performed 4D flow MR imaging in conjunction with 3D TOF MRA and compared their ability to identify the inflow zone of unruptured cerebral aneurysms. ⋯ 4D flow MR imaging can demonstrate the inflow zone and provide inflow velocity profiles. In aneurysms whose angle of the neck-section plane is obtuse vis-a-vis the imaging section on 3D TOF MRA scans, transluminal color-coded 3D MRA may depict the inflow zone reliably.