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Background and Purpose: To determine whether progression of MRI-defined vascular disease predicts subsequent vascular events in the elderly., Methods: The Cardiovascular Health Study, a longitudinal cohort study of vascular disease in the elderly, allows us to address this question because its participants had 2 MRI scans≈5 years apart and have been followed for ≈9 years since the follow-up scan for incident vascular events., Results: Both MRI-defined incident infarcts and worsened white matter grade were significantly associated with heart failure, stroke, and death, but not transient ischemic attacks, angina, or myocardial infarction. Strongest associations occurred when both incident infarcts and worsened white matter grade were present for heart failure (hazard ratio, 1.79; 95% confidence interval, 1.18-2.73), stroke (hazard ratio, 2.58; 95% confidence interval, 1.53-4.36), death (hazard ratio, 1.69; 95% confidence interval, 1.28-2.24), and cardiovascular death (hazard ratio, 1.97; 95% confidence interval, 1.24-3.14)., Conclusions: Progression of MRI-defined vascular disease identifies elderly people at increased risk for subsequent heart failure, stroke, and death. Whether aggressive risk factor management would reduce risk is unknown.

Rationale and Objectives: A near real-time and fully automatic method for calculation of the midsagittal plane (MSP) for magnetic resonance (MR) diffusion and perfusion images is introduced., Materials and Methods: The method is based on the Kullback-Leibler's (KL) measure quantifying the difference between two intensity distributions. The MSP is a sagittal plane with the highest KL measure. The method was validated quantitatively for 61 diffusion-weighted imaging (DWI), cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), peak height (PKHT), and time to peak (TPP) data sets of 11 stroke patients based on the ground truth provided by two raters., Results: Average angular errors are less than 1 degrees for DWI and less than 2 degrees for CBF and CBV. Average distance errors measured in the worst case (on the brain's bounding box) are less than 2.5 mm for DWI and less than 5 mm for CBF and CBV. This algorithmic accuracy is at the level of interrater variability. Results obtained for the other perfusions maps (MTT, PKHT, TTP) were inferior; therefore, processing of CBF or CBV is preferred for accurate and robust calculation of the MSP from perfusion maps. Calculation of the MSP takes about half a second on a standard computer., Conclusions: The proposed method is near real-time and fully automatic, and neither user interaction nor parameter setting is needed. It does not require preprocessing of data. The method potentially is useful in rapid and automated processing of MR stroke diffusion and perfusion images.

Background and Purpose: Magnetic resonance imaging (MRI) scans in the elderly commonly show white matter findings that may raise concerns. We sought to document incidence, manifestations, and predictors of worsening white matter grade on serial imaging., Methods: The Cardiovascular Health Study is a population-based, longitudinal study of 5888 people aged 65 years and older, of whom 1919 have had extensive initial and follow-up evaluations, including 2 MRI scans separated by 5 years. Scans were read without clinical information in standard side-by-side fashion to determine worsening white matter grade., Results: Worsening was evident in 538 participants (28%), mostly (85%) by 1 grade. Although similar at initial scan, participants with worsening white matter grade, compared with those without, experienced greater decline on modified Mini-Mental State examination and Digit-Symbol Substitution test (both P< or =0.001) after controlling for potential confounding factors, including occurrence of transient ischemic attack or stroke between scans. Independent predictors of worsening white matter grade included cigarette smoking before initial scan and infarct on initial scan. Otherwise, predictors differed according to white matter grade on initial scan. For low initial grade, increased age, increased diastolic blood pressure, increased high-density lipoprotein cholesterol, and decreased low-density lipoprotein cholesterol were associated with increased risk of worsening. For high initial grade, any cardiovascular disease and low ankle-arm index were associated with decreased risk of worsening, whereas use of diuretics and statins were associated with increased risk., Conclusions: Worsening white matter grade on serial MRI scans in elderly is common, is associated with cognitive decline, and has complex relations with cardiovascular risk factors.

Background and Purpose: We have previously reported that several "silent" infarcts found on magnetic resonance imaging (MRI) were a risk factor for stroke. Several recent reports have shown that high white matter grade (WMG) and increasing WMG over time were risk factors for stroke. We tested the hypothesis that high WMG > or =2 was a predictor of risk for stroke, independent of other risk factors., Methods: We examined the extent of white matter hyperintensity on cranial MRI of 3293 participants from the Cardiovascular Health Study (CHS). The degree of white matter hyperintensity was graded from least severe (grade=0) to most severe (grade=9). Participants were followed-up for an average of 7 years for the occurrence of a stroke. Clinical stroke diagnoses were based on hospital records reviewed by an adjudication committee expert in stroke diagnosis. During this period, 278 strokes occurred. Results The relative risk of stroke increased significantly as the WMG increased. The risk of stroke was 2.8% per year for participants with high WMG (grades > or =5), compared with only 0.6% for participants with grades 0 to 1.Conclusions The risk of stroke with high WMG is independent of traditional stroke risk factors and persists when controlling for MRI infarcts, another subclinical imaging marker of cerebrovascular disease. Assessment of white matter disease may be valuable in assessing future risk of stroke.

Study Objectives: To examine whether sleep-disordered breathing is associated with white matter disease in the brainstem., Design: A population-based longitudinal study., Setting: Allegheny County, PA; Sacramento County, CA; and Washington County, MD., Patients or Participants: A total of 789 individuals, aged 68 years or older, drawn from the Sleep Heart Health Study., Interventions: N/A., Measurements and Results: The participants underwent home polysomnography in 1995-1998 and cerebral magnetic resonance imaging in both 1992-1993 and 1997-1998. The apnea-hypopnea index was not associated with white matter disease in the brainstem, with or without adjusting for age, sex, race, community, body mass index, smoking status, alcohol use, systolic blood pressure, and the use of antihypertensive medication. In contrast, the arousal index (number of arousals per hour of sleep) was inversely associated with brainstem white matter disease (odds ratio = 0.75 for a SD increase in the arousal index, 95% confidence interval: 0.62, 0.92)., Conclusions: The frequency of apneas and hypopneas was not associated with brainstem white matter disease in these older adults. A unique relationship with arousal frequency suggests that ischemic changes in the brainstem may be associated with arousals during sleep.

Magnetic resonance (MR) diffusion imaging allows detection of cerebral ischemia within minutes of onset, and the temporal evolution of diffusion characteristics enables differentiation of acute from chronic stroke. T2-weighted MR imaging demonstrates infarcted tissue but fails to demonstrate acutely ischemic regions. Furthermore, the similar signal intensity characteristics of acute and chronic stroke on T2-weighted images limit the ability to determine the acuteness of an infarct. Diffusion imaging thus has tremendous potential for helping direct the treatment of acute ischemic stroke. Controversy exists over the pathophysiology of underlying changes in diffusion and the reversibility of changes after reperfusion in humans. There is also a lack of reproducibility in the time course of diffusion changes between research centers. Use of optimal diffusion imaging strategies results in increased conspicuity of ischemic regions and increased reproducibility of diffusion constants between research centers. An understanding of the principles of diffusion imaging and current controversies in the field is necessary for optimal application of this technique in the evaluation and treatment of cerebral ischemia.