Journal of neuroimaging : official journal of the American Society of Neuroimaging
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Fat embolism syndrome complicates open fractures involving long bones, although it occasionally follows nontraumatic conditions. Incomplete forms of the syndrome (ie, cerebral fat embolism) represent a challenge to diagnosis, and brain MRI represents a valuable diagnostic tool. ⋯ MRI with T2 and diffusion-weighted images revealed multiple, reversible brain lesions, suggesting vasogenic edema and consistent with this entity. At present, MR imaging is the most sensitive technique to evaluate cerebral fat embolism.
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Merrill P Spencer and John M Reid applied the Hagen-Poiseuille law, continuity principle, and cerebrovascular resistance to describe a theoretical model of the relationship between the flow velocity, flow volume, and decreasing size of the residual vessel lumen. The model was plotted in a graph that became widely known as the Spencer's curve. Although derived for a smooth and axis-symmetric arterial stenosis of a short length in a segment with no bifurcations being perfused at stable arterial pressures and viscosity, this model represents a milestone in understanding cerebral hemodynamics with long-lasting practical and research implications. This review summarizes several hemodynamic principles that determine velocity and flow volume changes, explains how the model aids interpretation of cerebrovascular ultrasound studies, and describes its impact on clinical practice and research.
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Comparative Study
Cerebral atrophy measurement in clinically isolated syndromes and relapsing remitting multiple sclerosis: a comparison of registration-based methods.
Brain atrophy is a proposed marker of disease progression in multiple sclerosis (MS). Many magnetic resonance imaging-based methods of atrophy quantification exist, but their relative sensitivity and precision is unclear. Our aim was to compare atrophy rates from the brain boundary shift integral (BBSI), structural image evaluation, using normalization of atrophy (SIENA) (both registration-based methods) and segmented brain volume difference, in patients with clinically isolated syndromes (CIS), relapsing remitting MS (RRMS), and controls. ⋯ Registration-based techniques are more precise and sensitive than segmentation-based methods in measuring brain atrophy, with BBSI and SIENA providing comparable results.