Antidepressant-related microstructural changes in the external capsule.

Several magnetic resonance imaging (MRI) studies have reported that antidepressant medications are strongly linked to brain microstructural alterations. Notably, external capsule alterations have been reported to be a biological marker for therapeutic response. However, prior studies did not investigate whether a change in the neurite density or directional coherence of white matter (WM) fibers underlies the observed microstructural alterations.

FMRI of working memory in patients with mild cognitive impairment and probable Alzheimer's disease.

The goals of this study were to evaluate brain activation in patients with probable Alzheimer's disease (AD), mild cognitive impairment (MCI), and controls while performing a working memory (WM) task. Eleven AD patients, ten MCI subjects, and nine controls underwent functional magnetic resonance imaging (fMRI) while performing a visual WM task. Statistical parametric maps of brain activation were obtained in each group, and group activation difference maps were generated.

Spatio-temporal analysis of auditory cortex activation as detected with silent event related fMRI.

Functional magnetic resonance imaging (fMRI) allows neuroscientists to assess brain function by evaluating haemodynamic activity (blood flow) when a stimulus is present or absent. In clinical practice, the hearing levels of individuals are determined using an audiometer that allows presentation of a pure-tone of specific intensity and frequency. Functional images of the auditory nervous system have been obtained using stimuli such as pure-tone, speech, noise, etc.

Percutaneous translumbar spinal cord compression injury in dogs from an angioplasty balloon: MR and histopathologic changes with balloon sizes and compression times.

Background And Purpose: Our previous model of spinal cord injury (SCI) included six dogs undergoing 30-minute compression with a balloon in the subarachnoid space. We determined whether various balloon sizes and compression times creates a gradation of injuries.

Methods: In 17 dogs (including our original six), angioplasty balloons 2, 4, or 7 mm in diameter (2 cm long) were inflated at T6 for 30, 120, or 240 minutes.

Silent functional magnetic resonance imaging (FMRI) of tonotopicity and stimulus intensity coding in human primary auditory cortex.

Objectives: The aims of this study were to determine the feasibility of obtaining auditory cortex activation evoked by pure tones presented at threshold and suprathreshold hearing levels, to evaluate tonotopicity of the primary auditory cortex, and to determine the effect of stimulus intensity on auditory cortex activation using silent functional magnetic resonance imaging (fMRI).

Methods: Sixteen subjects with normal hearing underwent silent fMRI. An audiometer was used to deliver pure tones of 1000, 2000, and 4000 Hz to the left ear.

Functional magnetic resonance imaging of activation in subcortical auditory pathway.

Objectives: Functional magnetic resonance imaging (fMRI) has been used to investigate activation of the auditory cortex; however, assessment of activation in the subcortical auditory pathway has been challenging. The aim of this study was to examine neural correlates of cortical and subcortical auditory activation evoked by pure-tone stimulus using silent fMRI.

Study Design: Prospective analysis.

Evaluation of auditory cortex activation by using silent FMRI.

Purpose: To evaluate auditory cortex activation evoked by pure-tone stimulus using silent functional magnetic resonance imaging (FMRI).

Material And Methods: Nine volunteers with normal hearing as determined with pure-tone audiometry were studied. Auditory cortex activation was evoked by pure-tone stimuli presented monaurally at 1,000, 2,000, and 4,000 Hz.

Hypoxia imaging in brain tumors.

Assessment of the oxygenation status of brain tumors has been studied increasingly with imaging techniques in light of recent advances in oncology. Tumor oxygen tension is a critical factor influencing the effectiveness of radiation and chemotherapy and malignant progression. Hypoxic tumors are resistant to treatment, and prognostic value of tumor oxygen status is shown in head and neck tumors.

Percutaneous translumbar spinal cord compression injury in a dog model that uses angioplasty balloons: MR imaging and histopathologic findings.

Background And Purpose: Previous animal models for spinal cord injury required laminectomy and exposure of the spinal cord to create direct trauma, compromising imaging by both surgical artifact and the nature of the production of the injury. Our purpose was to study a model that uses percutaneous intraspinal navigation with an angioplasty balloon, providing a controlled degree of spinal cord compression and allowing improved MR imaging of spinal cord injury.

Methods: Nine mongrel dogs were studied.

Use of functional MR to map language in multilingual volunteers.

Purpose: To use functional MR imaging to compare brain activation during processing of languages in which multilingual volunteers are fluent with brain activation during processing of languages in which they are not fluent.

Methods: Echoplanar images were obtained for five right-handed male multilingual subjects who performed a language task in three languages, one of which was a language in which the subject was not fluent. The functional MR technique included echoplanar images obtained at 1 per second during cycles of rest and performance of the task, from which functional images were processed by means of cross-correlation analysis.