Deep Hyperintensities Research Articles

Obstructive sleep apnea and white matter hyperintensities: correlation or causation?

Obstructive sleep apnea (apnea) is thought to cause small vessel ischemic episodes in the brain from hypoxic events, postulated as white matter hyperintensities (hyperintensities) identified on MRI which are implicated in cognitive decline. This study sought to evaluate these correlations. A retrospective evaluation of adults who underwent polysomnography (4/1/2016 to 4/30/2017) and a brain MRI prior to apnea diagnosis or within a year post-diagnosis was completed. MRI visual evaluation of hyperintensities using Fazekas scores were collected blind to clinical data. Collated clinical/MRI data were stratified and analyzed using chi-square, fishers t-tests, ANOVA/ANCOVA and linear regression. Stratification by apnea category revealed no significant differences in any variables including hyperintensity measures (Fazekas p=0.1584; periventricular p=0.3238; deep p=0.4618; deep total p=0.1770). Stratification by Fazekas category, periventricular and deep hyperintensities revealed increasing prevalence with age (p=0.0001); however, apnea categories were not significantly associated (Fazekas p=0.1479; periventricular p=0.3188; deep p=0.4503), nor were any individual apnea indicators. Continuous apnea measurements werre not associated with any hyperintensity factor; total deep hyperintensities were not associated with any apnea factors. Continuous BMI was not found to be associated with any apnea or hyperintensity factors. Only hypertension was noted to be associated with Fazekas (p=0.0045), deep (p=0.0010) and total deep (p=0.0021) hyperintensities; however, hypertension was not associated with apnea category (p=0.3038) or any associated factors. These data suggest apneas alone from OSA are insufficient to cause WMH, but other factors appear to contribute to the complex development of small vessel ischemic injury associated with age and cognitive decline.

Decline in Total Cerebral Blood Flow Is Linked with Increase in Periventricular but Not Deep White Matter Hyperintensities

To retrospectively investigate the association between changes in total cerebral blood flow and progression of total, periventricular, and deep white matter hyperintensities over time. The institutional ethics review board approved the protocol for the prospective magnetic resonance (MR) imaging study, and all participants gave written informed consent. Participants also agreed to future retrospective analysis of their MR data for research purposes. In this substudy of the Prospective Study of Pravastatin in the Elderly at Risk, investigators performed a repeated MR imaging examination after an average interval of 33 months (standard deviation, 1.4) in 390 elderly men and women (ages 70-82 years at baseline) without dementia who were at high vascular risk. White matter hyperintensities were quantified with a semiautomatic method, and total cerebral blood flow was measured with a gradient-echo phase-contrast MR imaging technique. The association between total cerebral blood flow and volume of white matter hyperintensities was analyzed with logistic regression. There was no association between baseline cerebral blood flow and prevalence of total, periventricular, or deep white matter hyperintensities at baseline MR imaging. Moreover, decline in cerebral blood flow was not associated with increase in total load of white matter hyperintensities. When the total volume of white matter hyperintensities was separated into periventricular and deep hyperintensities, for every 50 mL/min decrease in total cerebral blood flow there was a 1.32 (95% confidence interval: 1.06, 1.66; P = .015) increase in risk for developing periventricular white matter hyperintensities; there was no association, however, between decrease in total cerebral blood flow and risk of developing deep white matter hyperintensities (odds ratio, 1.00 [95% confidence interval: 0.79, 1.25]; P = .98). Decline in total cerebral blood flow is associated with increase in volume of periventricular but not deep white matter hyperintensities.

Sporadic Creutzfeldt?Jakob disease

To investigate a possible relationship between the severity of pathological and radiological lesions in diffusion-weighted MRI (DWI) we compared DWI findings from 6 sequential brain MRI scans with pathological features of numerous tissue blocks of different cortical and subcortical regions in a case of autopsy-proven sporadic CJD. Whereas DWI and pathological examination revealed multifocal, cortical and deep hyperintensities at corresponding localizations, no correlation between the degree of severity of radiologically visible and pathological damage was found. The characteristic focal involvement and extension of lesions of the cortex and the basal ganglia bilaterally shown by DWI may be an argument for the spreading of the disease per contiguitatem.

White matter lesions on magnetic resonance imaging in dementia with Lewy bodies, Alzheimer’s disease, vascular dementia, and normal aging

OBJECTIVESAlzheimer’s disease and vascular dementia are associated with an increase in changes in white matter on MRI. The aims were to investigate whether white matter changes also occur in dementia...

Orientation-dependent changes in MR signal intensity of articular cartilage: a manifestation of the "magic angle" effect.

To study magnetic resonance (MR) imaging pattern of normal hyaline articular cartilage in the knee joint with regard to the contribution of the "magic angle" effect to the MR signal. Thirty-two healthy volunteers were imaged in a standard supine position in a 1.5-T unit using spin echo and gradient echo sequences. Nine volunteers were reimaged with the knee flexed. The signal behavior of the hyaline cartilage of the femoral condyles was evaluated qualitatively and quantitatively. The extended and flexed positions of the nine volunteers were compared. A superficial and a deep hyperintense layer and a hypointense middle cartilage layer were observed. Segments of increased signal intensity were visible along the condyles; a magic angle effect on signal intensity was evident in the hypointense middle layer with both gradient echo and spin echo images. The MR signal behavior of hyaline cartilage is influenced by the alignment of the collagen fibers within the cartilage in relation to the magnetic field. Failure to recognize this effect may lead to inaccurate diagnosis.

White Matter Hyperintensities in Parkinson's Disease

To verify recent preliminary data indicating that white matter hyperintensities on magnetic resonance imaging are more abundant in patients with Parkinson's disease (PD) than in healthy subjects and to examine possible correlation between these abnormalities and clinical features of PD. Magnetic resonance imaging data on patients with PD and normal subjects were compared as to frequency, extent, and topographic location of white matter hyperintensities; moreover, in the PD group, we studied the possible correlation of white matter hyperintensities with clinical features such as severity, disease duration, and therapy. The outpatient clinic of the Institute of Clinical Neurology and the Neuroradiology Unit of the University of Pisa (Italy). We studied 102 nondemented patients with idiopathic PD and 68 sex- and age-matched healthy controls, all screened for absence of cerebrovascular risk factors. White matter hyperintensities were classified as periventricular hyperintensities and deep hyperintensities. Frequency, extent, and topographic location of both periventricular and deep hyperintensities were evaluated. The clinical parameters examined were disease duration, treatment type, and disease severity (using Hoehn and Yahr staging and the Unified Parkinson's Disease Rating Scale), as well as disease progression index (ratio between Hoehn and Yahr stage and disease duration). The frequency and the extent of periventricular hyperintensities were significantly higher in patients with PD than in healthy subjects. Moreover, within the PD group, the patients who had periventricular hyperintensities had significantly shorter disease duration and greater disease severity, ie, a higher disease progression index, than those who did not. These data suggest that periventricular hyperintensities may represent a marker for a clinical subtype of PD characterized by a more rapid neurodegenerative process.