MRI features associated with acute appendicitis.

Objectives: To identify MRI features associated with appendicitis.

Methods: Features expected to be associated with appendicitis were recorded in consensus by two expert radiologists on 223 abdominal MRIs in patients with suspected appendicitis. Nine MRI features were studied: appendix diameter >7 mm, appendicolith, peri-appendiceal fat infiltration, peri-appendiceal fluid, absence of gas in the appendix, appendiceal wall destruction, restricted diffusion of the appendiceal wall, lumen or focal fluid collections.

Comparison of imaging strategies with conditional contrast-enhanced CT and unenhanced MR imaging in patients suspected of having appendicitis: a multicenter diagnostic performance study.

Purpose: To compare the diagnostic performance of imaging strategies with magnetic resonance (MR) imaging and computed tomographic (CT) imaging in adult patients suspected of having appendicitis.

Materials And Methods: Institutional review board approval was obtained prior to study initiation, and patients gave written informed consent. In a multicenter diagnostic performance study, adults suspected of having appendicitis were prospectively identified in the emergency department.

Late-onset dementia: structural brain damage and total cerebral blood flow.

Purpose: To prospectively compare indicators of structural brain damage and total cerebral blood flow in patients with late-onset dementia, subjects of the same age with optimal cognitive function, and young subjects.

Materials And Methods: The institutional ethics committee approved the studies, and all participants (or their guardians) gave informed consent. The test group included 17 patients older than 75 years (four men, 13 women; median age, 83 years) and with a diagnosis of dementia according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition.

Age-related changes in normal-appearing brain tissue and white matter hyperintensities: more of the same or something else?

Background And Purpose: Cerebral white matter (WM) hyperintensities are a frequent finding in elderly people, and lowering of cerebral magnetization transfer ratio (MTR) has been observed. The aim of this study was to assess the relationship between age-related WM hyperintensities and MTR changes in the brain.

Methods: We performed MR imaging in a group of young subjects, a group of elderly individuals with minimal WM hyperintensities, and a group of elderly individuals with abundant WM hyperintensities.

Basal cerebral blood flow is dependent on the nitric oxide pathway in elderly but not in young healthy men.

Objective: Brain perfusion is tightly regulated over a wide range of blood pressures by local regulation of cerebral blood flow (CBF). Ageing is associated with impaired CBF and impaired nitric oxide mediated vasodilator responses. The role of nitric oxide in the regulation of basal CBF in young and older subjects was investigated, using the nitric oxide synthase inhibitor L-NMMA as pharmacological tool.

Automatic model-based contour detection and blood flow quantification in small vessels with velocity encoded magnetic resonance imaging.

Rationale And Objectives: The quantitative assessment of blood flow in peripheral vessels from phase-contrast magnetic resonance imaging studies requires the accurate delineation of vessel contours in cross-sectional magnetic resonance images. The conventional manual segmentation approach is tedious, time-consuming, and leads to significant inter- and intraobserver variabilities. The aim of this study was to verify whether automatic model-based segmentation decreases these problems by fitting a model to the actual blood velocity profile.

Cerebral hemodynamics and white matter hyperintensities in CADASIL.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary small-vessel disease caused by mutations in the NOTCH3 gene on chromosome 19. On magnetic resonance imaging (MRI), subcortical white matter hyperintensities and lacunar infarcts are visualized. It is unknown whether a decrease in cerebral blood flow or cerebrovascular reactivity is primarily responsible for the development of white matter hyperintensities and lacunar infarcts.

MR assessment of cerebral vascular response: a comparison of two methods.

Purpose: To compare the results and reproducibility of two MR-based methods of measuring the cerebrovascular response (CVR).

Materials And Methods: In eight volunteers, CVR was assessed with two MR-based methods upon a challenge with acetazolamide. CVR was assessed by measuring changes in total cerebral blood flow (TCBF) using phase contrast (PC) MRI, and by measuring perfusion MRI.

Reproducibility of total cerebral blood flow measurements using phase contrast magnetic resonance imaging.

Purpose: To evaluate reproducibility of total cerebral blood flow (CBF) measurements with phase contrast magnetic resonance imaging (pcMRI).

Materials And Methods: We repeated total CBF measurements in 15 healthy volunteers with and without cardiac triggering, and with and without repositioning. In eight volunteers measurements were performed at two different occasions.

Nitric oxide mediates hypoxia-induced cerebral vasodilation in humans.

Nitric oxide (NO) plays a pivotal role in the regulation of peripheral vascular tone. Its role in the regulation of cerebral vascular tone in humans remains to be elucidated. This study investigates the role of NO in hypoxia-induced cerebral vasodilatation in young healthy volunteers.