BOLD delay times using group delay in sickle cell disease

International audienceSickle cell disease (SCD) is an inherited blood disorder that effects red blood cells, which can lead to vasoocclu-sion, ischemia and infarct. This disease often results in neurological damage and strokes, leading to morbidity and mortality. Functional Magnetic Resonance Imaging (fMRI) is a non-invasive technique for measuring and mapping the brain activity. Blood Oxygenation Level-Dependent (BOLD) signals contain also information about the neurovascular coupling, vascular reactivity, oxygenation and blood propagation. Temporal relationship between BOLD fluctuations in different parts of the brain provides also a mean to investigate the blood delay information. We used the induced desaturation as a label to profile transit times through different brain areas, reflecting oxygen utilization of tissue. In this study, we aimed to compare blood flow propagation delay time between these patients and healthy subjects in areas vascularized by anterior, middle and posterior cerebral arteries. At first, BOLD changes in these areas were almost simultaneous and shorter in the SCD patients, because of their increased brain blood flow. Secondly, the analysis of a patient with a stenosis on the anterior cerebral artery indicated that signal of the area vascularized by this artery lagged the MCA signal. These findings suggested that sickle cell disease causes blood propagation modifications, and these changes could be used as a biomarker of vascular damage

Low-frequency fluctuation amplitude analysis of resting-state fMRI for sickle cell disease patients

International audienceSickle cell disease may result in neurological damage and strokes, leading to morbidity and mortality. The inability of conventional magnetic resonance imaging to predict impending stroke underlies the need for other neuroimaging markers risk. In this study, we analyzed neuronal processes at resting state and more particularly how this disease affects the default mode network. The amplitude of low frequency fluctuations was used to reflect areas of spontaneous BOLD signal across brain regions. We compared the activations of sickle cell disease patients to a control group with variance analysis and t-test. Significant differences in different parts among the two groups were observed, especially in the default mode network areas and cortical regions near large cerebral arteries. These findings suggest that sickle cell disease can cause some activation modifications near vessels, and these changes could be used a biomarker of the malady

Analysis of Hemodynamic Changes and Bold Signals of Sickle Cell Disease Patients during Desaturation

International audienceUsing near­infrared spectroscopy (NIRS), previous studies have shown that sickle­cell disease (SCD) patients have low cerebral oxygen saturation values. Moreover, the hemoglobin S in sickle cell disease has impaired oxygen carrying capacity. Here, we propose to investigate the effect of induced desaturation on the SCD brain. In particular, we analyzed the falling functional magnetic resonance imaging (fMRI) response during hypoxia, which results from local concentration changes in paramagnetic deoxy­hemoglobin (DHB). Moreover, we also explore the near­infrared spectroscopy (NIRS) changes in oxygenated and deoxygenated hemoglobin from the human prefrontal cortex

Tract specific analysis in patients with sickle cell disease

International audienc

Diffuse T1-MRI White Matter Volume Decrease in Patients with Sickle Cell Disease

International audienceSickle cell disease (SCD) is a genetic blood disorder associated with anemia, chronic vascular damage, overt stroke, silent cerebral infarctions, and early mortality. Patients with SCD have increased cerebral blood flow to compensate for their anemia but nevertheless exhibit regional cerebralhypo-perfusion and neurocognitive decline. Previous volumetric studies in SCD have shown delayed growth, gray matter (GM) loss, white matter (WM) loss, and decreased cortical thickness compared with control subjects. Diffusion-tensor imaging have demonstrated compromised WM integrity in major fiber pathways diffusely throughout the brain. Further regional investigations of structural outcome could potentially help expand our understanding of the neurobiology of SC

Vascular risk profile and white matter hyperintensity volume among Mexican Americans and non-Hispanic Whites: The HABLE study

INTRODUCTION: Among vascular risk factors we hypothesized that an increased prevalence of diabetes in Hispanics would be associated with greater white matter hyperintensity (WMH) volume, which may contribute to cognitive decline. METHODS: A total of 1318 participants (60% female; 49% Hispanic, 51% non-Hispanic White; age 66.2 ± 8.9 years) underwent clinical evaluation and brain magnetic resonance imaging (MRI). WMH volume associations were assessed with age, sex, and ethnicity and then with vascular risk factors in a selective regression model. RESULTS: WMH volume was greater with older age ( \u3c .0001), Hispanic ethnicity ( = .02), and female sex ( = .049). WMH volume was best predicted by age, diastolic blood pressure, hypertension history, hemoglobin A1c (HbA1c), white blood cell count, and hematocrit ( \u3c .01 for all). Elevated HbA1c was associated with greater WMH volume among Hispanics (parameter estimate 0.08 ± 0.02, \u3c .0001) but not non-Hispanic Whites (parameter estimate 0.02 ± 0.04, = .5). DISCUSSION: WMH volume was greater in Hispanics, which may be partly explained by increased WMH volume related to elevated HbA1c among Hispanics but not non-Hispanic Whites