Persistent hypoglossal artery: MRI, MRA and digital subtraction angiography.

We present the MRI, MRA and digital subtraction angiography (DSA) findings in a persistent hypoglossal artery found incidentally in a patient with cutaneous and intracranial haemangiomata.

Glial cell-derived neurotrophic factor (GDNF)-induced migration and signal transduction in corneal epithelial cells.

Purpose: To identify signal-transduction pathways induced by glial cell-derived neurotrophic factor (GDNF) in corneal epithelial cells and to characterize its effect on cell migration.

Methods: Expression of GDNF receptor (GFR) alpha-1 in human corneal epithelium was detected by RT-PCR and Western blot analysis. Expression and phosphorylation of Ret, activation of focal adhesion kinase (FAK) and mitogen-associated protein kinase (MAPK) signaling pathways, and phosphorylation of paxillin by GDNF were investigated by immunoprecipitation and Western blot analysis in primary human corneal epithelial cells and a corneal epithelial cell line.

How do concentration and dosage of the contrast agent affect the signal change in perfusion-weighted magnetic resonance imaging? A computer simulation.

In this study we investigated the effect of varying both concentration and dosage of an intravenously administered MR contrast agent on the concentration-time curve in brain tissue. Aside from injection time and injection rate, our model considers the distribution of transit-time between injection site and brain but it is independent from pulse rate, heart volume or other circulation parameters. The width of the transit-time distribution and the concentration-time course in the brain were computed according to indicator dilution theory.

Does the "keyhole" technique improve spatial resolution in MRI perfusion measurements? A study in volunteers.

We examined the potential of the 'keyhole' technique to improve spatial resolution in perfusion-weighted MRI on whole-body imagers with standard gradient hardware. We examined 15 healthy volunteers. We acquired a high-resolution image with 256 phase-encoding steps before a bolus-tracking procedure.

Diffusion-weighted imaging of the brain: comparison of stimulated- and spin-echo echo-planar sequences.

We used a rat model of focal cerebral ischaemia to compare stimulated-echo (STE) and spin-echo (SE) echo planar (EPI) diffusion-weighted sequences as regards image quality and accuracy of calculation of apparent diffusion coefficients (ADC). Focal cerebral ischaemia was induced by endovascular occlusion of the middle cerebral artery in five rats. MRI was performed on a 2.

Clustering of childhood mortality in rural Burkina Faso.

Background: Childhood mortality is a major public health problem in sub-Saharan Africa. For the implementation of efficient public health systems, knowledge of the spatial distribution of mortality is required.

Methods: Data from a demographic surveillance research project were analysed which comprised information obtained for about 30 000 individuals from 39 villages in northwest Burkina Faso (West Africa) in the period 1993--1998.

Stroke magnetic resonance imaging within 6 hours after onset of hyperacute cerebral ischemia.

We studied the diagnostic and prognostic value of diffusion- and perfusion-weighted magnetic resonancce imaging (DWI and PWI) for the initial evaluation and follow-up monitoring of patients with stroke that had ensued less than 6 hours previously. Further, we examined the role of vessel patency or occlusion and subsequent recanalization or persistent occlusion for further clinical and morphological stroke progression so as to define categories of patients and facilitate treatment decisions. Fifty-one patients underwent stroke magnetic resonance imaging (DWI, PWI, magnetic resonance angiography, and T2-weighted imaging) within 3.

Low-field interventional MRI in neurosurgery: finding the right dose of contrast medium.

MRI is increasingly being used as an interventional tool in neurosurgery. The field strength of "intraoperative" MR systems is usually lower than that of imagers commonly used for diagnostic purposes. However, lesion enhancement and apparent lesion extent depend on field strength.

Transient enlargement of contrast uptake on MRI after linear accelerator (linac) stereotactic radiosurgery for brain metastases.

Purpose/objective: With the increasing number of patients successfully treated with stereotactic radiosurgery for brain metastases, decision making after therapy based on follow-up imaging findings becomes more and more important. Magnetic resonance imaging (MRI) is the most sensitive means for follow-up studies. The objective of this study was to investigate the treatment outcome of our radiosurgery program and to describe the response of brain metastases to contrast-enhanced MRI after linear accelerator (linac) stereotactic radiosurgery and identify factors to distinguish among local control and local failure.

Diffusion-weighted imaging of the spine using radial k-space trajectories.

Introduction: Diffusion-weighted MR imaging (DWI) of the spine requires robust imaging methods, that are insensitive to susceptibility effects caused by the transition from bone to soft tissue and motion artifacts due to breathing, swallowing, and cardiac motion. The purpose of this study was to develop a robust imaging method suitable for DWI of the spine.

Methods And Subjects: A radial k-space spin echo sequence has been implemented, which is self-navigating because each acquisition line passes through the origin of k-space.

Noise correction for the exact determination of apparent diffusion coefficients at low SNR.

Noise in MR image data increases the mean signal intensity of image regions due to the usually performed magnitude reconstruction. Diffusion-weighted imaging (DWI) is especially affected by high noise levels for several reasons, and a decreasing SNR at increasing diffusion weighting causes systematic errors when calculating apparent diffusion coefficients (ADCs). Two different methods are presented to correct biased signal intensities due to the presence of complex noise: 1) with Gaussian intensity distribution, and 2) with arbitrary intensity distribution.

Antiarrhythmic drug carvedilol inhibits HERG potassium channels.

Objective: The aryloxypropanolamine carvedilol is a multiple action cardiovascular drug with blocking effects on alpha-receptors, beta-receptors, Ca(2+)-channels, Na(+)-channels and various native cardiac K(+) channels, thereby prolonging the cardiac action potential. In a number of clinical trials with patients suffering from congestive heart failure, carvedilol appeared to be superior to other beta-blocking agents in reducing total mortality. Given the multiple pharmacological actions of carvedilol, this may be due to specific channel blockade rather than beta-antagonistic activity.

Monocrystalline iron oxide nanoparticles: possible solution to the problem of surgically induced intracranial contrast enhancement in intraoperative MR imaging.

Background And Purpose: Intraoperative MR imaging is increasingly being used to control the extent of surgical resection; however, surgical manipulation itself causes intracranial contrast enhancement, which is a source of error. Our purpose was to investigate the potential of monocrystalline iron oxide nanoparticles (MIONs) to solve this problem in an animal model.

Methods: In male Wistar rats, surgical lesions of the brain were produced.

Gadolinium-enhanced magnetic resonance dacryocystography in patients with epiphora.

Purpose: Digital subtraction dacryocystography (DS-DCG) is considered the "gold standard" in the assessment of the nasolacrimal duct system but fails to delineate the soft tissue structures that surround the lacrimal drainage apparatus. The goal of this study was to compare high resolution MR surface coil imaging with DS-DCG to determine the value of gadolinium-enhanced MR dacryocystography (MR-DCG) in patients with epiphora.

Method: We performed bilateral MR-DCG and unilateral DS-DCG in 11 patients (aged 3-70 years) with epiphora using Gd-DTPA-containing eyedrops (Magnevist; 78.

Cerebral MR perfusion imaging: first clinical application of a 1 M gadolinium chelate (Gadovist 1.0) in a double-blinded randomized dose-finding study.

The purpose of this study was to evaluate efficacy and safety of the 1 M gadolinium chelate Gadovist 1.0 for assessment of cerebral hemodynamics with dynamic susceptibility contrast-enhanced magnetic resonance (MR) imaging. Eighty-nine patients with carotid artery stenosis or cerebral infarcts were included in this multicenter, double-blinded study using five dose groups from 0.

Irradiation for inhibition of endothelial cell growth in vitro.

The clinical effect of ionising radiation on ocular neovascularisations is controversial, not only because of the variety of treatment modalities. The aim of our study was to investigate an experimental model which allows to evaluate radiation parameters and to study the mechanism of the inhibitory effect on neoangiogenesis. In vitro experiments were performed using human umbilical vein endothelial cells and human corneal keratocytes.

The value of the Kurtzke Functional Systems Scales in predicting incomplete bladder emptying.

Study Design: A field study was conducted in 40 patients with multiple sclerosis (MS) by comparing their residual urine volumes with the Kurtzke Functional Systems Scales for pyramidal (PFS) or bladder functions (BFS).

Objectives: To determine whether raised residual urine volumes necessitating intermittent self catheterisation can be predicted by the PFS or BFS.

Setting: Department of Uro-Neurology, The National Hospital for Neurology and Neurosurgery, University College London Hospitals Trust, London, UK.

Feasibility and practicality of MR imaging of stroke in the management of hyperacute cerebral ischemia.

Background And Purpose: Neuroimaging techniques such as diffusion- and perfusion-weighted MR imaging have been proposed as tools for advanced diagnosis in hyperacute ischemic stroke. There is, however, substantial doubt regarding the feasibility and practicality of applying MR imaging for the diagnosis of stroke on a routine basis, especially with respect to possible delay for specific treatment such as thrombolysis. In this study, we tested whether MR imaging of stroke is safe, fast, and accurate, and whether the gain in additional information can be used in the daily routine without a loss of time and a risk of suboptimal treatment for the patient with stroke.

MRI of acute experimental intracerebral hematoma.

The purpose of the study was to evaluate the ability of different MR-sequences to detect and delineate experimentally produced hyperacute intracerebral hematomas in rats. Twenty male Sprague-Dawley rats received a unilateral hematoma of various volumes by stereotactic injection of fresh autologous arterial blood into the right caudatoputamen. MRI was performed up to 30 min after-generation of each hematoma.

Monitoring intravenous recombinant tissue plasminogen activator thrombolysis for acute ischemic stroke with diffusion and perfusion MRI.

Background And Purpose: Intravenous recombinant tissue plasminogen activator (rtPA) administration is an effective therapy for ischemic stroke when initiated within 3 hours and possibly up to 6 hours after symptom onset. To improve patient selection, a fast diagnostic tool that allows reliable diagnosis of hemorrhage and ischemia, vessel status, and tissue at risk at an early stage may be useful. We studied the feasibility of stroke MRI for the initial evaluation and follow-up monitoring of patients undergoing intravenous thrombolysis.

Magnetisation transfer ratio is low in normal-appearing cerebral white matter in patients with normal pressure hydrocephalus.

We measured the magnetisation transfer ratios (MTR) of normal-appearing rostral (PR) and caudal (PC) periventricular white matter, the genu (CG) and the splenium (CS) of the corpus callosum and the thalamus (TH) in 12 patients with normal-pressure hydrocephalus (NPH) and compared them with 16 healthy control subjects. We found a significantly lower MTR in the NPH group than in the normal group for PR, PC, CG, and CS but not for TH. MT measurements give additional information which cannot be gained by conventional MRI, suggesting that NPH is associated with diffuse white matter damage, even in normal-appearing cerebral white matter.

Neurotrophic factors in the human cornea.

Purpose: To investigate neurotrophic growth factors and corresponding receptors in human and rabbit corneal epithelium and stroma.

Methods: Transcription of nerve growth factor (NGF), neurotrophin 3 (NT-3), NT-4, brain-derived neurotrophic factor (BDNF), glial cell line- derived neurotrophic factor (GDNF), and receptors Trk A-E, was investigated by reverse transcription-polymerase chain reaction. DNA dot blot analysis allowed to estimate transcription levels.

Reducing motion artefacts in diffusion-weighted MRI of the brain: efficacy of navigator echo correction and pulse triggering.

Diffusion-weighted MRI (DWI) is extremely sensitive to motion of the object being examined. Pulse triggering and navigator echo correction are methods for reducing motion artefacts which can be combined with conventional DWI sequences. Implementation of these methods in imaging sequences with a readout of one, three, or five echoes is presented and imaging results compared in a study of five healthy volunteers.

Endovascular therapy of arteriovenous fistulae with electrolytically detachable coils.

We report our experience in using Guglielmi electrolytically detachable coils (GDC) alone or in combination with other materials in the treatment of intracranial or cervical high-flow fistulae. We treated 14 patients with arteriovenous fistulae on brain-supplying vessels--three involving the external carotid or the vertebral artery, five the cavernous sinus and six the dural sinuses--by endovascular occlusion using electrolytically detachable platinum coils. The fistula was caused by trauma in six cases.

Intraoperative MR imaging increases the extent of tumor resection in patients with high-grade gliomas.

Background And Purpose: MR is being used increasingly as an intraoperative imaging technique. The purpose of this study was to test the hypothesis that intraoperative MR imaging increases the extent of tumor resection, thus improving surgical results in patients with high-grade gliomas.

Methods: Thirty-eight patients with intracranial high-grade gliomas underwent 41 operations.