White matter lesion (WML) of presumed vascular origin is one of the common imaging manifestations of cerebral small vessel diseases, which is the main reason of cognitive impairment and even vascular dementia in the elderly. However, there is a lack of early and effective diagnostic methods currently. In recent years, studies of diffusion tensor imaging (DTI) and resting-state functional magnetic resonance imaging (rs-fMRI) have shown that cognitive impairment in patients with WMLs is associated with disrupted white matter microstructural and brain network connectivity. Therefore, it’s speculated that DTI and rs-fMRI can be effective in early imaging diagnosis of WMLs-related cognitive impairment. This article reviews the role and significance of DTI and rs-fMRI in WMLs-related cognitive impairment.
ObjectiveTo investigate the association between the imaging markers of ischemic cerebral small vessel disease and the occurrence of large hemispheric infarction (LHI).MethodsWe consecutively enrolled the patients with cerebral infarction in the middle cerebral artery blood supply area who admitted to the Department of Neurology, West China Hospital, Sichuan University between January 1st, 2015 and March 30th, 2016, and underwent head CT/MRI scans within one month of onset. LHI was defined as: the hypodensity was larger than 1/2 of the blood supply area of middle cerebral artery or more than 1/3 of the cerebral hemisphere within 6 hours on head CT at admission, or the infarction area was larger than 2/3 of the ipsilateral hemisphere on head MRI at admission. The basic clinical data and imaging data were collected, and the independent predictors of LHI and its independent correlation with ischemic cerebrovascular disease were explored by univariate and multivariate analyses.ResultsA total of 503 patients were included, 111 (22.1%) with LHI and 392 (77.9%) with non-LHI. Compared with the non-LHI patients, the LHI patients had a lower prevalence of white matter lesions, a lower Fazekas score, a lower prevalence of Fazekas score > 1, a lower prevalence of lacunae, a lower proportion of diabetes mellitus, a higher atrial fibrillation proportion of history, a shorter time from onset to treatment, a higher National Institute of Health Stroke Scale (NIHSS) score at admission, and a lower Glasgow Coma scale score; the distributions of TOAST types and locations of vascular stenosis were different (P<0.05). Multivariate analyses showed that white matter lesions [odds ratio (OR)=0.182, 95% confidence interval (CI) (0.050, 0.660), P=0.010], higher Fazekas score [OR=0.770, 95% CI (0.611, 0.970), P=0.027], and Fakazes score > 1 [OR=0.490, 95%CI (0.259, 0.928), P=0.029] were independent protective factors of LHI, while lacunae was not an independent factor of LHI [OR=0.583, 95% CI (0.265, 1.279), P=0.178]. Higher NIHSS score and history of atrial fibrillation were independent risk factors for LHI (P<0.001).ConclusionsThe occurrence and severity of white matter lesions (higher Fazekas score and Fazekas score > 1) are more in non-LHI group, and are independently related to the occurrence of LHI. The results suggest that ischemic preconditioning may have a protective effect on brain.
The mechanisms underlying the impact of metabolic syndrome on cognitive dysfunction in patients with schizophrenia remain unclear. The present study employed a two-factor factorial design to investigate the effects of metabolic syndrome on white matter microstructure in schizophrenia and its association with cognitive function. A total of 187 participants were included and classified into four groups based on the diagnoses of schizophrenia and metabolic syndrome: schizophrenia patients with metabolic syndrome (SZ-wMS), schizophrenia patients without metabolic syndrome, healthy controls with metabolic syndrome, and healthy controls without metabolic syndrome. Diffusion tensor imaging data were acquired. Using diffusion tensor model, fractional anisotropy (FA) was calculated to characterize the microstructural integrity of white matter. Peripheral metabolic indices and multiple domains of cognitive function were also assessed. The SZ-wMS group showed further reduced FA in the right sagittal stratum. Within the two-factor analytical framework, an interaction effect between metabolic syndrome and schizophrenia on FA in the right sagittal stratum was identified. Correlation analyses revealed that reduced FA in the right sagittal stratum was associated with impaired language function in patients with schizophrenia. Moreover, mediation analysis indicated that body mass index might indirectly affect language function by influencing FA in the right sagittal stratum. In summary, reduced integrity of white matter fibers in sagittal stratum may represent a potential neural mechanism underlying the comorbidity of schizophrenia and metabolic syndrome and may be associated with language dysfunction in schizophrenia.