Neuroimaging clinics of North America
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Neuroimaging Clin. N. Am. · May 2006
ReviewArterial spin labeling: benefits and pitfalls of high magnetic field.
Arterial spin labeling (ASL) techniques are MR imaging methods designed to measure the endogenous perfusion signal coming from arterial blood by manipulation of its magnetization. These methods are based on the subtraction of two consecutively acquired images: one acquired after preparation of the arterial blood magnetization upstream to the area of interest, and the second without any manipulation of its arterial magnetization. The subtraction of both images provides information on the perfusion of the tissue present in the slice of interest. ⋯ Other effects related to poorer magnetic filed homogeneities and reduced T(2) relaxation times, however, will counterbalance both effects partially. In this article, the pros and cons of the use of ASL at high field are summarized, after a brief description of the major techniques used and their theoretical limitations. Finally, a summary of the few existing dedicated ASL perfusion techniques available are presented.
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Neuroimaging Clin. N. Am. · Feb 2006
ReviewAdvanced neuroimaging of pediatric brain tumors: MR diffusion, MR perfusion, and MR spectroscopy.
This article highlights the MR imaging techniques of MR perfusion, MR diffusion, and MR spectroscopy in the evaluation of the child with a pediatric brain tumor. These techniques are complementary to conventional MR imaging in providing tumor physiologic information useful for diagnosis and therapy.
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With increasing life expectancy in developed countries, the incidence of Alzheimer's disease (AD) and its socioeconomic impact are growing. Increasing knowledge of the mechanisms of AD facilitates the development of treatment strategies aimed at slowing down or preventing neuronal death. ⋯ There is increasing evidence that neuroimaging and cerebrospinal fluid and blood biomarkers may provide information that may reduce sample sizes and observation periods. The Alzheimer's Disease Neuroimaging Initiative will help identify clinical, neuroimaging, and biomarker outcome measures that provide the highest power for measurement of longitudinal changes and for prediction of transitions.
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Neuroimaging Clin. N. Am. · Nov 2005
ReviewThe role of quantitative structural imaging in the early diagnosis of Alzheimer's disease.
The goal of this article is to review the role of structural neuroimaging in the diagnosis of Alzheimer's disease (AD). We present relevant neuroanatomy, highlight progress in the domain of AD imaging, and review the clinical characteristics of the prodromal phase of AD. ⋯ The article delineates the differences between subjects who have mild cognitive impairment and AD, which illustrate the spreading of the pathology with disease progression. The last section describes problems encountered in the differential diagnosis.
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Neuroimaging Clin. N. Am. · Aug 2005
ReviewExtending the time window for thrombolysis: evidence from acute stroke trials.
Data from intravenous tissue plasminogen activator studies have shown rapidly diminishing clinical benefit beyond 3 hours when noncontrast CT is used for treatment triage. Newer trials, such as the Desmoteplase in Acute Ischemic Stroke trial, have now successfully pushed the time window out to 9 hours using the concept of penumbral imaging and treatment of the perfusion-diffusion mismatch. Advanced imaging with CT or MR imaging protocols is providing a means for rational physiologic selection and outcomes assessment in stroke treatment.