White Matter Hyperintensity on Cranial Magnetic Resonance Imaging

Plasma amyloid levels and the risk of AD in normal subjects in the Cardiovascular Health Study

OBJECTIVES

To examine the association between incident Alzheimer disease (AD), and plasma A beta 1-40 and A beta 1-42 levels in normal and mild cognitive impairment (MCI) subjects in a subgroup of participants of the Cardiovascular Health Study Cognition Study.

METHODS

We determined the plasma A beta 1-40 and A beta 1-42 levels of 274 nondemented subjects (232 normals and 42 with MCI) in 1998-1999 and repeated the measurements in 2002-2003. The mean age of the subjects at baseline was 79.3 +/- 3.6 years. We examined the association between A beta levels and incident AD over the ensuing 4.5 years, controlling for age, cystatin C level (marker of glomerular function), apolipoprotein E-4 allele, Modified-Mini-Mental State Examination scores, and MRI-identified infarcts.

RESULTS

In an unadjusted prospective model in normal subjects, both A beta 1-40 and A beta 1-42 levels in 1998-1999 were associated with incident AD (n = 55) in 2002-2003 (longitudinal analysis). In the fully adjusted multivariate model, neither A beta 1-42 nor A beta 1-40 nor their ratio was associated with incident AD. However, adjustment had a very small effect on point estimates for A beta 1-42, from an odds ratio (OR) of 1.61 (p = 0.007) in the unadjusted model to an OR of 1.46 (p = 0.08) in the fully adjusted model. In 2002-2003 (cross-sectional analysis), only the unadjusted models showed that both peptides were associated with AD.

CONCLUSIONS

Plasma A beta levels are affected by age and by systemic and CNS vascular risk factors. After controlling for these conditions, A beta-40 and A beta 1-42 are weak predictors of conversion to Alzheimer disease (AD) in normal subjects and are only weakly associated with AD in cross-sectional analysis. Consequently, plasma levels of A beta do not seem to be useful biomarkers for AD.

Comparison of the inflammatory burden of truly asymptomatic carotid atheroma with atherosclerotic plaques contralateral to symptomatic carotid stenosis: an ultra small superparamagnetic iron oxide enhanced magnetic resonance study

BACKGROUND

Inflammation is a recognised risk factor for the vulnerable atherosclerotic plaque. The aim of this study was to explore whether there is a difference in the degree of magnetic resonance (MR) defined inflammation using ultra small superparamagnetic iron oxide (USPIO) particles within carotid atheroma in completely asymptomatic individuals and the asymptomatic carotid stenosis contralateral to the symptomatic side.

METHODS

20 symptomatic patients with contralateral disease and 20 completely asymptomatic patients underwent multi-sequence MR imaging before and 36 h after USPIO infusion. Images were manually segmented into quadrants and signal change in each quadrant was calculated following USPIO administration. Mean signal change was compared across all quadrants in the two groups.

RESULTS

The mean percentage of quadrants showing signal loss was 53% in the contralateral group compared with 31% in completely asymptomatic individuals (p = 0.025). The mean percentages showing enhancement were 44% and 65%, respectively (p = 0.024). The mean signal difference between the two groups was 8.6% (95% CI 1.6% to 15.6%; p = 0.017).

CONCLUSIONS

Truly asymptomatic plaques seem to demonstrate inflammation but not to the extent of the contralateral asymptomatic stenosis to the symptomatic side. Inflammatory activity may be a significant risk factor in asymptomatic disease.

Decreased white matter lesion volume and improved cognitive function after liver transplantation

Focal T2-weighted white matter lesions (WML) on brain magnetic resonance imaging (MRI), mimicking those seen in cerebrovascular small-vessel disease described in patients with persistent hepatic encephalopathy, decreased in volume with the improvement of hepatic encephalopathy. This outcome has been interpreted as a decrease in the edema that it is proposed to be involved in the pathogenesis of hepatic encephalopathy. We designed a study to further investigate potential changes in focal WML in the brains of patients with cirrhosis following liver transplantation and to study the relationship between these changes and overall cognitive function. We used MRI to measure the volume of supratentorial focal WML and a neuropsychological examination to assess cognitive function before and after liver transplantation in 27 patients with cirrhosis without signs of overt hepatic encephalopathy. Baseline MRI identified focal T2-weighted lesions in 19 patients (70.3%). The presence of WML was associated with older age but not with vascular risk factors, severity of liver function, or psychometric tests. A significant reduction in lesion volume was observed after liver transplantation (from a median of 1.306 cm(3) to 0.671 cm(3), P = 0.001). This decrease correlated with an improvement in an index of global cognitive function (r = -0.663; P < 0.001). This evolution indicates that lesion volume is partially related to a reversible type of tissue damage, which is compatible with brain edema.

CONCLUSION

Focal WML probably induced by age-related microvascular injury can decrease their volume with liver transplantation. The associated improvement of cognitive function supports a relationship between brain edema and minimal hepatic encephalopathy.

Silent brain infarcts: a systematic review

As the availability and quality of imaging techniques improve, doctors are identifying more patients with no history of transient ischaemic attack or stroke in whom imaging shows brain infarcts. Until recently, little was known about the relevance of these lesions. In this systematic review, we give an overview of the frequency, causes, and consequences of MRI-defined silent brain infarcts, which are detected in 20% of healthy elderly people and up to 50% of patients in selected series. Most infarcts are lacunes, of which hypertensive small-vessel disease is thought to be the main cause. Although silent infarcts, by definition, lack clinically overt stroke-like symptoms, they are associated with subtle deficits in physical and cognitive function that commonly go unnoticed. Moreover, the presence of silent infarcts more than doubles the risk of subsequent stroke and dementia. Future studies will have to show whether screening and treating high-risk patients can effectively reduce the risk of further infarcts, stroke, and dementia.

High Prevalence of Leukoaraiosis in Cerebral Magnetic Resonance Images of Patients on Peritoneal Dialysis

BACKGROUND

Leukoaraiosis is a term used to define the abnormal appearance of subcortical white matter of the brain by means of neuroimaging and is regarded as an intermediate surrogate of stroke. The goal of this study is to identify the prevalence of leukoaraiosis and analyze predictors of risk of leukoaraiosis.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

57 peritoneal dialysis (PD) patients without diabetes treated in 3 academic medical-associated dialysis units who did not have a history of cerebrovascular disease or neurological symptoms compared with a convenience sample of 57 age- and sex-matched hypertensive control subjects with normal renal function.

PREDICTOR

End-stage renal disease treated by PD compared with hypertension, adjusted for clinical and laboratory characteristics.

OUTCOME & MEASUREMENT

Hyperintense areas on magnetic resonance imaging T2 high-signal intensity scoring system.

RESULTS

The prevalence of leukoaraiosis was significantly greater in patients on PD therapy than controls (68.4% versus 17.5%; P < 0.001). High T2 signal intensity score in patients on PD therapy compared with controls was significantly higher in the anterior circulation of the brain, relatively sparing the posterior fossa. End-stage renal disease, age, and poor control of blood pressure were significant independent predictors of leukoaraiosis.

LIMITATIONS

There is the possibility that biases regarding the selection of enrolled patients had an influence on a study result.

CONCLUSIONS

Cerebral magnetic resonance imaging of PD patients without evidence of cerebrovascular disease showed a high prevalence of leukoaraiosis in the anterior circulation of the brain. Old age, poorly controlled hypertension, and the PD procedure itself and/or end-stage renal disease seem to be associated with the presence of leukoaraiosis.

Hypertension, cognitive decline, and dementia: an epidemiological perspective

Hypertension is a known risk factor for stroke, and thus for vascular dementia. However, recent large observational studies have suggested that high blood pressure may also play a role in Alzheimer's disease. The mechanisms linking hypertension to Alzheimer's disease remain to be elucidated, but white matter lesions seen on cerebral magnetic resonance imaging appear to be a good marker of this association. It is not yet clearly established whether lowering blood pressure reduces the risk of white matter lesions and dementia, so large trials dealing with this question are eagerly awaited. These future trials could confirm the hope that, by lowering blood pressure, we may have a preventive treatment for dementia. This issue is of major importance, as the number of cases of dementia is expected to rise sharply in the near future.

Association of Ambulatory Blood Pressure With Ischemic Brain Injury

Cerebral white matter hyperintensities on brain MRI (leukoaraiosis) are associated with increased risk of stroke and dementia. To assess the relationships of blood pressure level and circadian pattern with leukoaraiosis, we obtained 24-hour ambulatory blood pressure recordings and brain magnetic resonance images in 343 white and 267 black adults who were members of sibships that had ≥2 siblings with essential hypertension. In multiple linear regression models, factors associated with greater leukoaraiosis in both racial groups included age ( P ≤0.002), homocysteine levels ( P ≤0.006), and brain volume ( P ≤0.008). In blacks, ambulatory blood pressure measures associated with greater leukoaraiosis were higher awake, asleep, and 24-hour systolic and diastolic levels ( P ≤0.009 for each). In addition, there was a trend for smaller nocturnal declines in systolic and diastolic levels (ie, nondipping patterns) to be associated with greater leukoaraiosis, and all of these associations, except nondipping of diastolic level, remained or became significant after controlling for office blood pressure ( P <0.05 for each). In whites, among ambulatory blood pressure measures, only higher asleep diastolic levels trended toward association with greater leukoaraiosis. However, similar to findings in blacks, nondipping of systolic and diastolic ambulatory blood pressure levels were each associated with greater leukoaraiosis ( P ≤0.008), and all of these associations remained or became significant after controlling for office blood pressure ( P ≤0.009 for each). Higher ambulatory blood pressure levels and a nondipping circadian pattern contribute to greater leukoaraiosis volume after controlling for office blood pressure.

The 2006 William Feinberg lecture: shifting the paradigm from stroke to global vascular risk estimation

By the year 2010, it is estimated that 18.1 million people worldwide will die annually because of cardiovascular diseases and stroke. "Global vascular risk" more broadly includes the multiple overlapping disease silos of stroke, myocardial infarction, peripheral arterial disease, and vascular death. Estimation of global vascular risk requires consideration of a variety of variables including demographics, environmental behaviors, and risk factors. Data from multiple studies suggest continuous linear relationships between the physiological vascular risk modulators of blood pressure, lipids, and blood glucose rather than treating these conditions as categorical risk factors. Constellations of risk factors may be more relevant than individual categorical components. Exciting work with novel risk factors may also have predictive value in estimates of global vascular risk. Advances in imaging have led to the measurement of subclinical conditions such as carotid intima-media thickness and subclinical brain conditions such as white matter hyperintensities and silent infarcts. These subclinical measurements may be intermediate stages in the transition from asymptomatic to symptomatic vascular events, appear to be associated with the fundamental vascular risk factors, and represent opportunities to more precisely quantitate disease progression. The expansion of studies in molecular epidemiology and detection of genetic markers underlying vascular risks also promises to extend our precision of global vascular risk estimation. Global vascular risk estimation will require quantitative methods that bundle these multi-dimensional data into more precise estimates of future risk. The power of genetic information coupled with data on demographics, risk-inducing behaviors, vascular risk modulators, biomarkers, and measures of subclinical conditions should provide the most realistic approximation of an individual's future global vascular risk. The ultimate public health benefit, however, will depend on not only identification of global vascular risk but also the realization that we can modify this risk and prove the prediction models wrong.

Chronic ischemic cerebral white matter disease is a risk factor for nonfocal neurologic injury after total aortic arch replacement

OBJECTIVE

Leukoaraiosis (chronic ischemic white matter changes) on preoperative brain magnetic resonance imaging is common in patients having aortic arch surgery. This study sought to determine whether it is associated with adverse neurologic outcome in the postoperative period.

METHODS

Data were collected from a retrospective chart review of 142 patients in whom total aortic arch replacement was planned at the Cleveland Clinic between April 2000 and December 2004. All patients had preoperative brain magnetic resonance imaging evaluation. Leukoaraiosis severity was rated semiquantitatively using the Schelten's scale. Postoperative neurologic injuries were investigated by clinical examination and appropriate neuroimaging. They were stratified as type 1 (focal ischemic stroke) and type 2 (nonfocal neurocognitive changes, generalized seizures) injuries.

RESULTS

The following were independent predictors of type 1 neurologic injury: age (odds ratio 1.06 [1.01-1.13], P = .02) and moderate to severe aortic atheroma (odds ratio 4.4 [1.4-9.7], P = .012). Total white matter scores (odds ratio 1.16 [1.06-1.27], P = .002) and higher preoperative hemoglobin A1c levels (odds ratio 1.8 [1.00-3.50], P = .05) were significantly associated with type 2 neurologic injuries. Survival was 96%, and 4.2% had persistent focal neurologic deficits at the time of hospital discharge.

CONCLUSIONS

Leukoaraiosis is a significant independent predictor of nonfocal postoperative neurologic morbidity following aortic arch replacement surgery. Preoperative evaluation with magnetic resonance imaging allows identification of a patient subgroup at risk and implementation of strategies aimed at improving neurologic outcome.

Structural and Functional Imaging Correlates for Age-Related Changes in the Brain

In recent years, investigators have made significant progress in documenting brain structure and function as it relates to aging by using positron emission tomography, conventional magnetic resonance (MR) imaging, advanced MR techniques, and functional MR imaging. This review summarizes the latest advances in understanding physiologic maturation and aging as detected by these neuroimaging modalities. We also present our experience with MR volumetric and positron emission tomography analysis in separate cohorts of healthy subjects in the pediatric and adult age groups respectively. Our results are consistent with previous studies and include the following: total brain volume was found to increase with age (up to 20 years of age). Whole brain metabolism and frontal lobe metabolism both decrease significantly with age (38% and 42%, respectively), whereas cerebellar metabolism does not show a significant decline with age. Defining normal alterations in brain function and structure allows early detection of disorders such as Alzheimer's and Parkinson's diseases, which are commonly associated with normal aging.

Increased risk of death in community-dwelling older people with white matter hyperintensities on MRI

BACKGROUND

Previous studies in subjects with a history of stroke have shown that white matter hyperintensities (WMH) on MRI are associated with increased risk of death. However, it has not been determined whether WMH are independently related to death in community-dwelling older people without stroke.

METHODS

In a sample of community-dwelling people over 75 years with no history of stroke or other neurological diseases, WMH on brain MRI T2-weighted sequences were classified as grade 0, grade 1, or grade 2. Grade 2 WMH were identified in 36 subjects. Age- and sex-matched grade 0 and grade 1 WMH groups were selected for comparison to the grade 2 WMH group. All subjects underwent an initial clinical evaluation and were followed for a median of 11.8 years (interquartile range=10.7 to 12.2 years). Cox proportional-hazards analysis was used to determine the independent association between WMH and time to death from any cause.

RESULTS

In an unadjusted analysis, grade 2 WMH was associated with death from any cause (hazard ratio=1.98; 95% confidence interval=1.06, 3.70). After adjustment for hypertension, high cholesterol, diabetes, and coronary artery disease, grade 2 WMH remained significantly associated with death (hazard ratio=2.31; 95% confidence interval=1.21, 4.40) in these age- and sex-matched groups.

CONCLUSIONS

Severe WMH increase the risk of death, even in community-dwelling elderly without stroke or other neurological disease, independent of other covariates including hypertension, age, and coronary artery disease.

Methodology for measuring cerebrovascular disease burden

Biological aging of the brain is partly attributable to aging of the cerebrovascular circulation and the effects of these vascular changes on the brain. A variety of techniques ranging from simple, clinical scores to complex radiological techniques have been used in an attempt to understand, describe and quantify this process. Simultaneously attempts have been made to relate these changes to cognitive and physical changes and the risk of dementia and stroke associated with brain aging. The most frequently used clinical scores are the Framingham Stroke Risk Profile and the Hachinski Ischemic Score for vascular dementia. Radiological techniques to estimate cerebrovascular burden include many varieties of ultrasonographic, computerized tomography (CT), magnetic resonance imaging (MRI) and nuclear medicine techniques. The radiological techniques evaluate the nature and extent of disease in the vessels supplying the brain and the pattern and extent of radiological evidence of damage to the brain both on static and dynamic imaging and are briefly outlined in this review. There are several studies using these techniques to study 'normal' aging populations, and the techniques used in the most widely known of these studies are briefly highlighted in this review.

Family-based association study of matrix metalloproteinase-3 and -9 haplotypes with susceptibility to ischemic white matter injury

Susceptibility to ischemic damage to the subcortical white matter of the brain has a strong genetic basis. Dysregulation of matrix metalloproteinases (MMPs) contributes to loss of cerebrovascular integrity and white matter injury. We investigated whether sequence variation in the genes encoding MMP3 and MMP9 is associated with variation in leukoaraiosis volume, determined by magnetic resonance imaging, in non-Hispanic whites and African-Americans using family-based association tests. Seven hundred and fifty-six white and 671 African-American individuals from sibships ascertained through two or more siblings with hypertension were genotyped for 7 and 8 haplotype-tagging polymorphisms in the MMP3 and MMP9 genes, respectively. MMP3 sequence variation was significantly associated with variation in leukoaraiosis volume in Whites. Two common haplotypes with opposing relationships to leukoaraiosis volume were identified. MMP9 sequence variation was also significantly associated with variation in leukoaraiosis volume in both African-Americans and Whites. Different haplotypes contributed to these associations in the two racial groups. These findings add to the growing body of evidence from animal models and human clinical studies suggesting a role of MMPs in ischemic white matter injury. They provide the basis for further investigation of the role of these genes in susceptibility and/or progression to clinical disease.

White matter grade and ventricular volume on brain MRI as markers of longevity in the cardiovascular health study

High white matter grade (WMG) on magnetic resonance imaging (MRI) is a risk factor for dementia, stroke and disability. Higher ventricular size is a marker of brain "atrophy." In the Cardiovascular Health Study (CHS) (n=3245) mean age 75 years, 50% black and 40% men, we evaluated WM and ventricular grade (VG), total, cardiovascular and noncardiovascular mortality and longevity before and after adjusting for numerous determinants of longevity over an approximate 10-12 years of follow-up. A low WMG and VG was a marker for low total, cardiovascular and noncardiovascular mortality and for increased longevity over 10+ years of follow-up. We estimated that a 75-year-old with WMG below median would have about a 5-6 years greater longevity and for VG about 3 years, than above the median even after adjustment for numerous risk factors. Low WMG and VG on MRI is a powerful determinant of long-term survival among older individuals.

Imaging Findings of Migraine

Increasingly sophisticated neuroimaging techniques have allowed researchers to begin to define functional and anatomical characteristics of migraine. This paper reviews current knowledge and techniques employed. Assessing present-day knowledge limitations it concludes that with parallel advances in the technology of imaging and the pathophysiologic understanding of migraine, a reliable biomarker may be discovered in the future.

Factors associated with geographic variations in stroke incidence among older populations in four US communities

BACKGROUND AND PURPOSE

In the Cardiovascular Health Study (CHS), we previously observed lower stroke incidence in Allegheny County, PA compared with the other 3 study sites. The purpose of this study was to study possible reasons for the lower stroke incidence in Allegheny County.

METHODS

CHS participants 65 years or older who were stroke-free at baseline (n=5639) were followed between 1989 to 1990 and 2000 for the development of stroke. Risk factors at baseline and their subsequent control were compared among both groups. Site-specific hazard ratios for stroke incidence were calculated using Cox regression models.

RESULTS

The unadjusted hazard ratio for total stroke incidence in Forsyth County, NC; Sacramento County, CA; and Washington County, MD combined compared with Allegheny County, PA was 1.74 (95% CI: 1.42, 2.14). After adjustment for age and other traditional risk factors, there was modest reduction of the excess hazard in non-Allegheny sites compared with Allegheny County (hazard ratio=1.52, 95% CI: 1.17, 1.98). Between baseline and the seventh-year visits, control of hypertension, diabetes, lipids, smoking, atrial fibrillation and transient ischemic attack were similar across sites. White matter grade > or = 3 on the baseline brain MRI was less common in Allegheny County (25.8% versus 36.3%, respectively; P<0.001) and accounted for 25% of the excess hazard in non-Allegheny sites compared with Allegheny County.

CONCLUSIONS

Site differences in stroke risk factors at baseline and subsequent control only partially explain site differences in stroke incidence. White matter grade as a possible integrated measure of exposure and control of risk factors may help in explaining geographic variations in stroke incidence.

Small vessel strokes

Small vessel disease is a common cause of cerebrovascular disease. It is responsible for ischemic and hemorrhagic strokes, cognitive decline, and asymptomatic disease. Millions of Americans are affected by silent strokes and white matter abnormalities. Lacunar stroke is the most common manifestation. Despite its importance, small vessel strokes remain understudied. There is a need for research focused on this prevalent stroke subtype to define optimal interventions to prevent stroke recurrence and cognitive impairment.

Silent Brain Infarction and Subcortical White Matter Lesions Increase the Risk of Stroke and Mortality: A Prospective Cohort Study

Silent brain infarction (SBI) and white matter lesions (periventricular hyperintensity [PVH] and subcortical white matter lesions [SWML] are detected in both stroke patients and normal elderly persons. We prospectively examined the association between these lesions and the risk of subsequent stroke and mortality in neurologically normal adults. Magnetic resonance imaging scans were performed in 2,684 neurologically normal subjects with no history of stroke (mean age, 58 +/- 7 years old at entry) who underwent our health screening of the brain. After the brain screening, we obtained information about clinical stroke onset and death using a questionnaire sent annually to all subjects. When a subject suffered from medical events, we confirmed the detailed information in a telephone interview and by asking the attending physician. SBI was defined as a focal T2-hyperintensity and T1-hypointensity lesion > 3 mm. PVH and SWML were graded according to their severity. The average follow-up period was 6.3 years. Stroke occurred in 102 subjects (3.8%), and 93 subjects died during follow-up. The incidence of clinical stroke was significantly higher in the subjects with SBI than in those without SBI. Marked PVH and marked SWML independently increased the risk of stroke (for SBI, stroke risk factor-adjusted odds ratio [OR] = 3.66, 95% confidence interval [CI] = 2.28-5.89; for marked PVH, stroke risk factor-adjusted OR = 2.08, 95% CI = 1.04-4.17; for marked SWML, stroke risk factor-adjusted OR = 2.73, 95% CI = 1.32-5.63). Regarding mortality, SBI and marked PVH increased the risk of death (for SBI, stroke risk factor-adjusted OR = 1.95, 95% CI = 1.16-3.29; for PVH, stroke risk factor-adjusted OR = 4.01, 95% CI = 1.91-8.45). Death attributable to stroke occurred more frequently in those subjects with SBI, marked PVH, and marked SWML. We conclude that SBI, marked PVH, and marked SWML are important risk factors for clinical stroke and that SBI and marked PVH also increase the risk of mortality.

Silent Cerebral White Matter Lesions and Their Relationship With Vascular Risk Factors in Middle-Aged Predialysis Patients With CKD

BACKGROUND

Silent cerebral white matter lesions are observed on magnetic resonance imaging (MRI) scans in elderly people, and they are related to vascular risk factors, particularly hypertension. No data on the prevalence and risk factors of white matter lesions in patients with chronic kidney disease (CKD) are available. The aim is to analyze the prevalence of white matter lesions and their determinants in this population.

METHODS

We studied 52 patients without diabetes with CKD (stage 3 or 4) aged 30 to 60 years (average, 49 years) and a group of 32 normotensive control subjects. MRI studies were performed and subcortical and periventricular white matter lesions were evaluated by using semiquantitative measures. Patients were classified into 2 groups depending on the presence or absence of white matter lesions. Echocardiographic studies and measures of markers of systemic inflammation (C-reactive protein and interleukin 6) also were performed.

RESULTS

White matter lesions were more prevalent in patients with CKD than controls (33% versus 6%; P = 0.008). Patients with CKD who had white matter lesions were older; had a greater history of cardiovascular disease and vascular nephropathy as a primary cause of renal disease and greater levels of systolic blood pressure, pulse pressure, left ventricular mass index, and C-reactive protein; and were administered more antihypertensive drugs than patients with CKD without white matter lesions. Stage and duration of CKD were not related to the presence of white matter lesions. After adjusting for several factors, only vascular nephropathy (odds ratio, 15.6; 95% confidence interval, 1.27 to 191.54; P = 0.03) independently predicted an increased risk for white matter lesions.

CONCLUSION

One third of middle-aged patients with CKD have silent cerebral white matter lesions. Vascular nephropathy seems to be the most important factor related to the presence of these lesions, suggesting that white matter lesions reflect ischemic brain damage caused by generalized vascular damage.

Asymptomatic cerebrovascular disease and systemic diagnosis in stroke, atherothrombosis as a disease of the vascular tree

Atherosclerosis is a chronic vascular disease of true epidemic proportions. It is the first cause of death in developed countries and responsible for one quarter of documented deaths worldwide. Arteriosclerotic vascular disease is a systemic process which affects different organs; principally the heart, brain, and peripheral artery system. Despite well-documented differences, all manifestations of the disease share the same risk factors; albeit with varying degrees of impact. The concept of asymptomatic cerebrovascular disease is an important one for clinicians who treat stroke patients. The development of new neuroimaging and vascular evaluation techniques has enabled the presence of apparently silent lesions to be detected and their progress monitored in follow-up. Ultrasonography techniques enable the identification of atheromatous disease. Asymptomatic involvement of the cerebral parenchyma consists of ischemia, leukoaraiosis, and silent hemorrhage and can be detected using the available radiological techniques such as cranial CT, magnetic resonance, or gradient echo magnetic resonance imaging. From the point of view of prevention, it is of considerable importance to identify diagnostic markers for arteriosclerosis in asymptomatic patients in some, if not all, vascular territories. In view of the natural history of this disease and the impact it has on society, there is an increasing need to identify and understand the risk factors or vascular disease risk markers, so that the stratification of risk of an individual patient or in a specific population can be established, appropriate cerebrovascular assessments conducted, and appropriate therapeutic intervention initiated.

Treatment of leukoaraiosis

Altered signal intensity in the subcortical white matter on magnetic resonance imaging of the brain, referred to as leukoaraiosis, is frequently observed on imaging studies in elderly persons and was previously considered a benign accompaniment of aging. However, recent studies have found a clear association between the presence of leukoaraiosis and an increased risk for stroke, cognitive decline, and dementia. Moreover, epidemiologic studies have shown an association of leukoaraiosis with age, and several risk factors that are amenable to treatment, including smoking, hypertension, diabetes, homocysteinemia, hyperlipidemia, and excess alcohol use. Although results from prospective trials are not available, current evidence suggests that vigorous treatment of cardiovascular disease risk factors may prevent the development or progression of leukoaraiosis and the attendant risks of stroke and dementia.

Determinants of vascular dementia in the Cardiovascular Health Cognition Study

OBJECTIVE

The authors evaluated 3,375 participants without dementia at the time of MRI in 1991 to 1994 over 5.7 years for incident dementia and type of dementia.

METHODS

Incidence of and risk factors for vascular dementia (VaD) were measured using both pre-MRI and modified State of California Alzheimer's Disease Diagnostic and Treatment Centers (ADDTC) post-MRI review and further classified Alzheimer disease (AD) by the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria.

RESULTS

Approximately 44% (213) of 480 incident dementia cases were classified as possible or probable VaD by ADDTC. The incidence of VaD increased with age and was greater in blacks than whites. Risk factors for VaD included age, Modified Mini-Mental State Examination, high white matter grade, number of MRI infarcts, ventricular size, and history of stroke.

CONCLUSIONS

Vascular disease in the brain is prevalent among incident dementia cases. There is a substantial overlap between cases classified as Alzheimer disease by Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association and vascular dementia (VaD) by modified State of California Alzheimer's Disease Diagnostic and Treatment Centers criteria. The substantial contribution of vascular disease would be missed without inclusion of MRI. Treatment of risk factors for VaD could have an important impact on incidence of dementia.

Neurological Soft Signs as the Stroke Risk in Sickle Cell Disease

Sickle cell disease (SCD) is a common form of hemoglobinopathy and is highly prevalent worldwide. Silent cerebral infarction, which represents infarction without clinical signs, is a risk factor for clinical stroke in patients with SCD. It is well known that silent infarction predisposes patients with SCD to overt stroke. The aim of the present study is to investigate the effect of silent infarction on neurological soft signs (NSS), which demonstrate subtle impairments in sensory integration, motor coordination and the sequencing of complex motor acts and to evaluate whether NSS can be used in clinical practice to evaluate the patients at risk of stroke in SCD patients with silent infarction. Fifty-nine SCD patients without any documented history of cerebrovascular accident and 28 healthy controls were included in this study. All the patients with SCD were evaluated with cerebral magnetic resonance imaging. We found that the NSS scores were significantly higher in patients with silent cerebral infarction than those in patients without silent infarction and control subjects (p < 0.05). Importantly, there was no significant difference in the NSS scores between the patients without silent infarction and control subjects. These results indicate that high NSS scores represnt an important finding for diagnosis of silent infarction in SCD patients. As silent infarction increases the risk for stroke in patients with SCD, NSS can be used to provide additional information in diagnosis of the patients with possible stroke risk during the course of SCD.

Age-related cerebral white matter changes and pulse-wave encephalopathy: observations with three-dimensional MRI

Our purpose was to investigate leukoaraïosis (LA) using three-dimensional MR imaging combined with advanced image-processing technology to attempt to group signal abnormalities according to their etiology. Coronal T2-weighted fast fluid-attenuated inversion-recovery (FLAIR) sequences and three-dimensional T1-weighted fast spoiled gradient recalled echo sequences were used to examine cerebral white matter changes in 75 elderly people with memory complaint but no dementia. They were otherwise healthy, community-dwelling subjects. Three subtypes of LA were defined on the basis of their shape, geography and extent: the so-called subependymal/subpial LA, perivascular LA and "bands" along long white matter tracts. Subependymal changes were directly contiguous with ventricular spaces. They showed features of "water hammer" lesions with ventricular systematisation and a more frequent location around the frontal horns than around the bodies (P=.0008). The use of cerebrospinal fluid (CSF) contiguity criterion allowed a classification of splenial changes in the subpial group. Conversely, posterior periventricular lesions in the centrum ovale as well as irregular and extensive periventricular lesions were not directly contiguous with CSF spaces. The so-called perivascular changes showed features of small-vessel-associated disease; they surrounded linear CSF-like signals that followed the direction of perforating vessels. Distribution of these perivascular changes appeared heterogeneous (P ranging from .04 to 5.10(-16)). These findings suggest that subependymal/subpial LA and subcortical LA may be separate manifestations of a single underlying pulse-wave encephalopathy.

Fully automatic segmentation of white matter hyperintensities in MR images of the elderly

The role of quantitative image analysis in large clinical trials is continuously increasing. Several methods are available for performing white matter hyperintensity (WMH) volume quantification. They vary in the amount of the human interaction involved. In this paper, we describe a fully automatic segmentation that was used to quantify WMHs in a large clinical trial on elderly subjects. Our segmentation method combines information from 3 different MR images: proton density (PD), T2-weighted and fluid-attenuated inversion recovery (FLAIR) images; our method uses an established artificial intelligent technique (fuzzy inference system) and does not require extensive computations. The reproducibility of the segmentation was evaluated in 9 patients who underwent scan-rescan with repositioning; an inter-class correlation coefficient (ICC) of 0.91 was obtained. The effect of differences in image resolution was tested in 44 patients, scanned with 6- and 3-mm slice thickness FLAIR images; we obtained an ICC value of 0.99. The accuracy of the segmentation was evaluated on 100 patients for whom manual delineation of WMHs was available; the obtained ICC was 0.98 and the similarity index was 0.75. Besides the fact that the approach demonstrated very high volumetric and spatial agreement with expert delineation, the software did not require more than 2 min per patient (from loading the images to saving the results) on a Pentium-4 processor (512 MB RAM).