Detection and characterization of small infarcts in the caudate nucleus on 7 Tesla MRI: The SMART-MR study

Small infarcts are among the key imaging features of cerebral small vessel disease (CSVD), but remain largely undetected on conventional MRI. We aimed to evaluate (1) imaging criteria for the detection of small infarcts in the caudate nucleus on 7T MRI, (2) intra- and inter-rater agreement, (3) frequency and (4) detection rate on 7T versus 1.5T MRI. In 90 patients (68 ± 8 years) with a history of vascular disease from the SMART-MR study, we defined 7T imaging criteria for cavitated and non-cavitated small infarcts in the caudate nucleus. In a separate set of 23 patients from the SMART study, intra-rater and inter-rater agreement was excellent for presence, number, and individual locations (Kappa’s, ICCs, and Dice similarity coefficients ranged from 0.85 to 1.00). In the 90 patients, 21 infarcts (20 cavitated) in 12 patients were detected on 7T (13%) compared to 7 infarcts in 6 patients on 1.5T (7%). In conclusion, we established reproducible imaging criteria for the detection of small infarcts in the caudate nucleus on 7T MRI and showed that 7T MRI allows for a higher detection rate than conventional 1.5T MRI. These imaging criteria can be used in future studies to provide new insights into the pathophysiology of CSVD

Intracranial vessel wall lesions on 7T MRI and MRI features of cerebral small vessel disease-The SMART-MR study

The etiology of cerebral small vessel disease (CSVD) is the subject of ongoing research. Although intracranial atherosclerosis (ICAS) has been proposed as a possible cause, studies on their relationship remain sparse. We used 7 T vessel wall magnetic resonance imaging (MRI) to study the association between intracranial vessel wall lesions-a neuroimaging marker of ICAS-and MRI features of CSVD. Within the SMART-MR study, cross-sectional analyses were performed in 130 patients (68 ± 9 years; 88% male). ICAS burden-defined as the number of vessel wall lesions-was determined on 7 T vessel wall MRI. CSVD features were determined on 1.5 T and 7 T MRI. Associations between ICAS burden and CSVD features were estimated with linear or modified Poisson regression, adjusted for age, sex, vascular risk factors, and medication use. In 125 patients, ≥1 vessel wall lesions were found (mean 8.5 ± 5.7 lesions). ICAS burden (per + 1 SD) was associated with presence of large subcortical and/or cortical infarcts (RR = 1.65; 95%CI: 1.12-2.43), lacunes (RR = 1.45; 95% CI: 1.14-1.86), cortical microinfarcts (RR = 1.48; 95%CI: 1.13-1.94), and total white matter hyperintensity volume (b = 0.24; 95%CI: 0.02-0.46). Concluding, patients with a higher ICAS burden had more CSVD features, although no evidence of co-location was observed. Further longitudinal studies are required to determine if ICAS precedes development of CSVD

Vascular Risk Factors of Hippocampal Subfield Volumes in Persons without Dementia: The Medea 7T Study

BACKGROUND: Vascular risk factors have been associated with risk of Alzheimer's disease (AD) and volume loss of the hippocampus, but the associations with subfields of the hippocampus are understudied. Knowing if vascular risk factors contribute to hippocampal subfield atrophy may improve our understanding of vascular contributions to neurodegenerative diseases. OBJECTIVE: To investigate the associations between age, sex, and vascular risk factors with hippocampal subfields volumes on 7T MRI in older persons without dementia. METHODS: From the Medea 7T study, 283 participants (67±9 years, 68% men) without dementia had 7T brain MRI and hippocampal subfield segmentation. Subfields were automatically segmented on the 3D T2-weighted 7T images with ASHS software. Using linear mixed models, we estimated adjusted associations of age, sex, and vascular risk factors with z-scores of volumes of the entorhinal cortex (ERC), subiculum (SUB), Cornu Ammonis (CA)1, CA2, CA3, CA4, and dentate gyrus (DG), and tail as multivariate correlated outcomes. RESULTS: Increasing age was associated with smaller volumes in all subfields, except CA4/DG. Current smoking was associated with smaller ERC and SUB volumes; moderate alcohol use with smaller CA1 and CA4/DG, obesity with smaller volumes of ERC, SUB, CA2, CA3, and tail; and diabetes mellitus with smaller SUB volume. Sex, former smoking, and hypertension were not associated with subfield volumes. When formally tested, no risk factor affected the subfield volumes differentially. CONCLUSION: Several vascular risk factors were associated with smaller volumes of specific hippocampal subfields. However, no statistical evidence was found that subfields were differentially affected by these risk factors

Brain parenchymal changes on magnetic resonance imaging in cerebrovascular diseases

Cerebrovascular disease refers to a wide variety of conditions that lead to pathological changes in the blood vessels of the brain. These blood vessel changes can result in brain abnormalities. Although the clinical application of magnetic resonance imaging has substantially increased the knowledge on cerebrovascular diseases and their impact on the brain, there is a lack of knowledge with respect to several brain abnormalities that include white matter hyperintensities of vascular origin, microinfarcts in the deep gray matter and brain atrophy. This thesis examines the detection, risk factors and relation to clinical outcomes of white matter hyperintensities (WMH) of vascular origin, microinfarcts in the deep gray matter and brain atrophy. Data was used from the Second Manifestations of ARTerial disease-Magnetic Resonance (SMART-MR) study, a prospective cohort study at the University Medical Center Utrecht with the aim to investigate risk factors and consequences of brain changes on MRI in patients with symptomatic atherosclerotic disease. In the first part, we examine advanced quantitative features of WMH on MRI and their relation to clinical outcomes. After developing an algorithm to extract information on quantitative features of WMH from brain MRI scans, we showed that a greater volume and a more irregular shape of WMH were related to an increased risk of mortality and ischemic stroke. In the second part, we focus on the detection, risk factors and relation to cognitive functioning of microinfarcts in the deep gray matter on ultra-high field 7 tesla MRI. We observed that these lesions could be reliably detected on 7 tesla MRI, were associated with markers of both large vessel and small vessel disease, and were related to poorer cognitive functioning. In the last part, we examined potential risk factors for increased brain atrophy. We found that a reduced cerebral blood flow (measured on brain MRI) and mild carotid atherosclerosis on ultrasound pose risk factors for increased brain atrophy. The findings of this thesis may potentially be used in the future to identify patients who are at an increased risk for ischemic stroke, mortality and brain atrophy based on their brain MRI scan

Association of Ischemic Imaging Phenotype With Progression of Brain Atrophy and Cerebrovascular Lesions on MRI: The SMART-MR Study

BACKGROUND AND OBJECTIVE: To investigate the association of silent vascular lesions, imaging negative ischemia, and symptomatic cerebrovascular disease with long-term progression of brain atrophy and cerebrovascular lesions in patients with arterial disease. METHODS: Within the Second Manifestations of Arterial Disease-Magnetic Resonance (SMART-MR) study, stroke status of participants at baseline was classified as no cerebrovascular disease (reference group, n = 829), symptomatic cerebrovascular disease (n = 206), silent vascular lesion (n = 157), and imaging-negative ischemia (n = 90) according to clinical and MRI findings. With the use of linear mixed models, changes in brain and white matter hyperintensity (WMH) volumes at baseline and during 12 years of follow-up were studied in stroke classifications. Relative risks were estimated for new infarcts during follow-up associated with stroke classifications. Analyses were adjusted for age, sex, cardiovascular risk factors, and medications. RESULTS: Symptomatic cerebrovascular disease associated with 0.35 SD (95% confidence interval [CI] 0.24-0.47) smaller brain volume and 0.61 SD (95% CI 0.48-0.74) larger WMH volume at baseline and increased risk for new infarcts during follow-up (risk ratio [RR] 2.89, 95% CI 2.00-4.16). Silent vascular lesions were associated with 0.15 SD (95% CI 0.01-0.88) smaller brain volume, 0.02 SD (95% CI 0.01-0.03) steeper brain atrophy slope, and 0.48 SD (95% CI 0.32-0.64) larger WMH volume at baseline, in addition to increased risk for lacunes (RR 2.08, 95% CI 1.48-2.94). Individuals with imaging-negative ischemia had increased risk for cortical infarcts (RR 2.88, 95% CI 2.17-3.82). DISCUSSION: Patients with symptomatic cerebrovascular disease, silent vascular lesions, or imaging-negative ischemia have a different course of brain volume loss and cerebrovascular lesion development. These findings may have implications for future stroke risk and dementia and need further investigation

Intracranial Vessel Wall Lesions on 7T MRI (Magnetic Resonance Imaging) : Occurrence and vascular risk factors: The SMART-MR study

Background and Purpose- Intracranial vessel wall lesions are a novel imaging marker of intracranial atherosclerosis (ICAS), but data on their occurrence and risk factors are lacking. Our aim was to study the frequency, distribution, and risk factors of intracranial vessel wall lesions on 7T magnetic resonance imaging in patients with a history of vascular disease. Methods- Within the SMART-MR study (Second Manifestations of Arterial Disease-Magnetic Resonance), cross-sectional analyses were performed in 130 patients (68±9 years) with assessable 7T intracranial vessel wall-magnetic resonance imaging data. Associations between vascular risk factors and ICAS burden, defined as the total number of vessel wall lesions, were estimated using linear regression analyses with ICAS burden as the dependent variable, adjusted for age and sex. Results- Ninety-six percent of patients had ≥1 vessel wall lesion. The mean±SD (range) ICAS burden was 8.5±5.7 (0-32) lesions. Significant associations were found between ICAS burden and age ( b=2.0 per +10 years; 95% CI, 0.81- 3.10), systolic blood pressure ( b=0.9 per +10 mm Hg; 95% CI, 0.27-1.42), diabetes mellitus ( b=3.2 for presence of diabetes mellitus; 95% CI, 0.79-5.72), hemoglobin A1c level ( b=1.2 per +1%; 95% CI, 0.19-2.26), apoB (apolipoprotein-B) ( b=4.7 per +1 g/L; 95% CI, 0.07-9.35), and hs-CRP (high-sensitivity C-reactive protein) level ( b=2.7 for hs-CRP >3 mg/L; 95% CI, 0.22-5.11). No significant associations were found with sex, smoking, and other lipid-factors. Conclusions- Vessel wall lesions are a novel and direct magnetic resonance imaging marker of ICAS. In this cohort, 96% of patients had at least 1 lesion on 7T vessel wall-magnetic resonance imaging. More lesions were found with older age, higher systolic blood pressure, diabetes mellitus, and higher levels of hemoglobin A1c, apoB, and hs-CRP

The association between lacunes and white matter hyperintensity features on MRI : The SMART-MR study

Lacunes and white matter hyperintensities (WMHs) are features of cerebral small vessel disease (CSVD) that are associated with poor functional outcomes. However, how the two are related remains unclear. In this study, we examined the association between lacunes and several WMH features in patients with a history of vascular disease. A total of 999 patients (mean age 59 ± 10 years) with a 1.5 T brain magnetic resonance imaging (MRI) scan were included from the SMART-MR study. Lacunes were scored visually and WMH features (volume, subtype and shape) were automatically determined. Analyses consisted of linear and Poisson regression adjusted for age, sex, and total intracranial volume (ICV). Patients with lacunes (n = 188; 19%) had greater total (B = 1.03, 95% CI: 0.86 to 1.21), periventricular/confluent (B = 1.08, 95% CI: 0.89 to 1.27), and deep (B = 0.71, 95% CI: 0.44 to 0.97) natural log-transformed WMH volumes than patients without lacunes. Patients with lacunes had an increased risk of confluent type WMHs (RR = 2.41, 95% CI: 1.98 to 2.92) and deep WMHs (RR = 1.41, 95% CI: 1.22 to 1.62) and had a more irregular shape of confluent WMHs than patients without lacunes, independent of total WMH volume. In conclusion, we found that lacunes on MRI were associated with WMH features that correspond to more severe small vessel changes, mortality, and poor functional outcomes

The association between lacunes and white matter hyperintensity features on MRI : The SMART-MR study

Lacunes and white matter hyperintensities (WMHs) are features of cerebral small vessel disease (CSVD) that are associated with poor functional outcomes. However, how the two are related remains unclear. In this study, we examined the association between lacunes and several WMH features in patients with a history of vascular disease. A total of 999 patients (mean age 59 ± 10 years) with a 1.5 T brain magnetic resonance imaging (MRI) scan were included from the SMART-MR study. Lacunes were scored visually and WMH features (volume, subtype and shape) were automatically determined. Analyses consisted of linear and Poisson regression adjusted for age, sex, and total intracranial volume (ICV). Patients with lacunes (n = 188; 19%) had greater total (B = 1.03, 95% CI: 0.86 to 1.21), periventricular/confluent (B = 1.08, 95% CI: 0.89 to 1.27), and deep (B = 0.71, 95% CI: 0.44 to 0.97) natural log-transformed WMH volumes than patients without lacunes. Patients with lacunes had an increased risk of confluent type WMHs (RR = 2.41, 95% CI: 1.98 to 2.92) and deep WMHs (RR = 1.41, 95% CI: 1.22 to 1.62) and had a more irregular shape of confluent WMHs than patients without lacunes, independent of total WMH volume. In conclusion, we found that lacunes on MRI were associated with WMH features that correspond to more severe small vessel changes, mortality, and poor functional outcomes