Journal of neuroimaging : official journal of the American Society of Neuroimaging
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The Circle of Willis (COW) is the main collateral system between the bilateral carotid systems and the posterior circulation. COW normal variants are encountered in up to 62% of subjects. We hypothesize that, in patients with carotid artery stenosis, the presence of COW variants is a risk factor for leukoaraiosis. ⋯ The presence and the number of COW variants are associated with a higher leukoaraiosis volume in patients with significant internal carotid artery stenosis.
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Parturitional injuries refer to injuries sustained during and secondary to fetal delivery. The skull, brain, and head and neck regions are frequently involved. ⋯ In addition, a short discussion of the most common head and neck, facial, and spinal lesions is included. Various mimickers and risk factors are also presented.
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Case Reports
Low endogenous recanalization in embolic central retinal artery occlusion--the retrobulbar "spot sign".
Central retinal artery occlusion (CRAO) is most often indirectly diagnosed by lack of retinal perfusion. Direct embolus characterization may help to understand the natural course and low response to treatment. In a previous study we identified a hyperechoic signal within the optic nerve and in the central retinal artery ("spot sign"). ⋯ The hyperechoic spot sign may be an important predictive prognostic marker for persistent loss of vision. Its persistence may indicate calcified or cholesterol emboli and may explain the low therapeutic success rate to thrombolysis. Further studies on their origin and significance in atherosclerotic disease are warranted.
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Hypertrophic olivary degeneration (HOD) is an uncommon type of transneuronal degeneration. Case reports and case series described in the literature provide a foundation of our current knowledge of HOD. These reports have described HOD most frequently to be unilateral and occurring in association with lesions in the dentato-rubro-olivary pathway. Our purpose was to evaluate the rate of bilateral versus unilateral HOD in a large case series. ⋯ This study demonstrates that HOD is frequently bilateral. In slightly over 50% of patients with HOD, a lesion can be identified. In just under 50% patients with HOD, a lesion could not be identified and in these cases HOD was present bilaterally in the majority.
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Intensity variation between magnetic resonance images (MRI) hinders comparison of tissue intensity distributions in multicenter MRI studies of brain diseases. The available intensity normalization techniques generally work well in healthy subjects but not in the presence of pathologies that affect tissue intensity. One such disease is multiple sclerosis (MS), which is associated with lesions that prominently affect white matter (WM). ⋯ We developed a WM-independent T1w MRI normalization method and tested its performance. This method is suitable for longitudinal multicenter clinical studies for the assessment of the recovery or progression of disease affecting WM.