Increased cortical capillary transit time heterogeneity in Alzheimer's disease: a DSC-MRI perfusion study.

Alzheimer's disease (AD) is characterized by the accumulation of hyperphosphorylated tau and neurotoxic Aβ in the brain parenchyma. Hypoxia caused by microvascular changes and disturbed capillary flows could stimulate this build-up of AD-specific proteins in the brain. In this study, we compared cerebral microcirculation in a cohort of AD and mild cognitive impairment (MCI) patients with that of age-matched controls, all without a history of diabetes or of hypertension for more than 2 years, using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI).

Cerebral blood flow, blood volume, and mean transit time responses to propofol and indomethacin in peritumor and contralateral brain regions: perioperative perfusion-weighted magnetic resonance imaging in patients with brain tumors.

Background: The regional cerebral blood flow (CBF) response to propofol and indomethacin may be abnormal in patients with brain tumors. First, the authors tested the hypothesis that during propofol anesthesia alone and combined with indomethacin, changes in CBF, cerebral blood volume (CBV), and plasma mean transit time (MTT) differ in the peritumoral tissue compared with the contralateral normal brain region. Second, the authors tested the hypothesis that CBF and CBV are reduced and MTT is prolonged, in both regions during propofol anesthesia and indomethacin administration compared with propofol alone.

Interrater agreement for final infarct MRI lesion delineation.

Background And Purpose: Lesion volume measured on follow-up magnetic resonance imaging (MRI) is commonly used as an outcome parameter in clinical stroke trials. However, few studies have evaluated the optimal sequence choice and the interrater reliability of this outcome measure. The objective of this study was to quantify the geometric interrater agreement for lesion delineation of chronic infarcts on T2-weighted and fluid-attenuated inverse recovery (FLAIR) MRI.

MRI detection of early blood-brain barrier disruption: parenchymal enhancement predicts focal hemorrhagic transformation after thrombolysis.

Background And Purpose: Blood-brain barrier disruption may be a predictor of hemorrhagic transformation (HT) in ischemic stroke. We hypothesize that parenchymal enhancement (PE) on postcontrast T1-weighted MRI predicts and localizes subsequent HT.

Methods: In a prospective study, 33 tPA-treated stroke patients were imaged by perfusion-weighted imaging, T1 and FLAIR before thrombolytic therapy and after 2 and 24 hours.

[Imaging of the pathophysiology in acute stroke].

Recent developments in neuroimaging have changed the diagnostic aspect of acute stroke and improved our understanding of stroke pathophysiology. Both diffusion weighted MR imaging and CT are capable of detecting the infarcted volume damaged by cytotoxic edema. However, within six hours of stroke onset, DWI has both higher sensitivity and specificity than CT.

[Diagnostic imaging in dementia evaluation].

Introduction: The aim of the study was to evaluate the changes in diagnoses and treatment by structural scanning in dementia evaluation.

Material And Methods: 336 elderly, consecutively evaluated patients from two university memory clinics (mean age 75 y, mean MMSE 21.7), were retrospectively diagnosed without and with inclusion of scan results.

Ischemic injury detected by diffusion imaging 11 minutes after stroke.

A 78-year-old woman suffered a stroke inside a magnetic resonance scanner while being imaged because of a brief transient ischemic attack 2 hours earlier. Diffusion-weighted images obtained 11 minutes after stroke showed tissue injury not found on initial images. The data show early, abrupt diffusion changes in hypoperfused tissue, adding to our understanding of the progression of microstructural abnormalities in the hyperacute phase of stroke.

Do indomethacin and propofol cause cerebral ischemic damage? Diffusion-weighted magnetic resonance imaging in patients undergoing craniotomy for brain tumors.

Background: Diffusion-weighted magnetic resonance imaging was used to determine whether indomethacin and propofol induce cerebral ischemic damage in patients undergoing craniotomy for cerebral tumors. As a secondary aim, the authors investigated whether low jugular bulb oxygen saturation values were associated with brain parenchymal damage as evaluated by diffusion-weighted imaging.

Methods: Nine patients subjected to craniotomy for supratentorial brain tumors in propofol-fentanyl anesthesia were studied.

Final infarct size after acute stroke: prediction with flow heterogeneity.

Purpose: To compare acute measurements of flow heterogeneity (FH) and mean transit time (MTT) with follow-up data to determine which method yields better predictive measures of final infarct volumes.

Materials And Methods: Twenty-three patients with symptoms of stroke underwent magnetic resonance (MR) imaging during the acute stage, and the tissue at risk was estimated from MTT maps and maps generated by means of detecting abnormal FH. Final infarct volumes were calculated from T2-weighted follow-up MR image measurement.

Blood flow and ischemia within traumatic cerebral contusions.

Objective: To provide evidence of irreversible ischemia in cerebral contusions among patients with severe traumatic brain injuries and to clarify the potential viability of tissue in the pericontusional zone, quantitative regional cerebral blood flow (rCBF) measurements obtained with the xenon-enhanced computed tomographic method were correlated with the areas of contusions, by using image fusion.

Methods: rCBF measurements obtained during the acute phase (mean, 2 d after injury; range, 0-10 d) were statistically correlated with the extent of tissue necrosis identified as focal atrophy on late follow-up computed tomographic scans (mean time after the xenon-enhanced computed tomographic cerebral blood flow investigation, 265 d; range, 30-1047 d).

Results: Seventeen patients exhibited 26 traumatic contusions.

Time evolution of cerebral perfusion and apparent diffusion coefficient measured by magnetic resonance imaging in a porcine stroke model.

Purpose: To demonstrate the feasibility of sequential diffusion-weighted (DW) and perfusion-weighted (PW) magnetic resonance imaging (MRI) of a recently developed porcine stroke model and to evaluate the evolution of cerebral perfusion and the apparent diffusion coefficient (ADC) over time. Materials and Methods In five pigs, DW imaging (DWI) and PW imaging (PWI) was carried out for 7 hours after stroke onset, starting 1 hour after middle cerebral artery occlusion (MCAO).

Results: The DWI lesion volume increased significantly with time, and final DWI lesion volume correlated well with lesion area on histological sections (r = 0.