Biomedical subjects

Z Yetkin

Publications and source records attributed to Z Yetkin.

7 recordsLinked to original sources

PubMed1995

Atypical demyelinating lesions in patients with multiple sclerosis.

We describe an atypical MRI appearance of multiple sclerosis (MS). Lesions characterized on T2-weighted images by a well-defined rim of increased signal intensity and a concentric region of higher signal intensity were seen in 6 of 132 patients with MS. On T1-weighted images these lesions were evident as regions of low signal intensity, often with a rim of contrast enhancement or increased signal intensity. These appearances tended to be shown by new, evolving lesions.

Adult↗

PubMed1995

Functional magnetic resonance imaging of the central auditory pathway following speech and pure-tone stimuli.

Functional magnetic resonance imaging (FMRI) is a new noninvasive technique for imaging cerebral function. Studies of the human central auditory pathway examined responses in eight normal hearing volunteers following auditory stimuli, including narrative speech and pure-tone audiometry. The activation demonstrated by FMRI is modeled on an increase in regional blood flow with increased neuronal activity. The FMRI signals represent deoxyhemoglobin concentration changes in capillaries within the region of the brain that is activated. Brain activation was imaged in the superior temporal gyrus during text reading and pure tones. Activation in both text and pure-tone presentation did not vary with the intensity of the auditory stimulus and elicited a dominant response in the left temporal lobe. These observations demonstrate the capability of FMRI to correlate anatomic and functional relationships in the human central auditory pathway.

Acoustic Stimulation↗

PubMed1986

Gas in spinal articulations.

The purpose of this review is to illustrate, some for the first time, a variety of gas collections in lumbar facet joints and intervertebral discs and in the sacroiliac joint.

Arthrography↗

PubMedDate not supplied

Artifacts in functional magnetic resonance imaging from gaseous oxygen.

Unexpectedly large fluctuations in signal intensity were identified in the functional MRI (FMRI) of normal subjects breathing pure oxygen intermittently. To test the hypothesis that the signal changes were due to fluctuating concentrations of gaseous (paramagnetic) oxygen in the magnetic field, echo planar gradient echo images were acquired of a phantom contiguous to an oxygen mask through which pure oxygen was administered intermittently via plastic tubing. As a control, room air was administered intermittently or oxygen continuously in the same experimental protocol. Signal intensity changes of up to 60% temporally correlated with the administration of oxygen were produced in the phantom. In functional images prepared from the echo planar images, the signal intensity changes resulted in artifacts especially at interfaces in the phantom. The intermittent administration of pure oxygen during acquisition of data for FMRI may produce signal intensity changes that stimulate or obscure function.

Artifacts↗

PubMedDate not supplied

MR measurement of normal and pathologic brainstem diameters.

The dimensions of the brainstem were measured on magnetic resonance (MR) images to provide criteria for detecting brainstem enlargement. Twenty-eight normal adult subjects had MR imaging with sagittal partial-saturation and spin-echo sequences. Four patients with brainstem gliomas and three with cerebellar atrophy were also studied. Five measurements were made: (A) the distance between the interpeduncular fissure and the aqueduct, (B) the distance from the anterior surface of the cerebral peduncles to the aqueduct, (C) the distance between the anterior surface of the pons midway between the mesencephalon and medulla to the fourth ventricular floor, (D) the shortest anteroposterior diameter of the medulla at the pontomedullary junction, and (E) the shortest anteroposterior diameter of the medulla at the medullospinal junction. Pontine diameter could be measured more reproducibly and accurately than mesencephalic or medullary diameters. In four patients with glioma, one or more of the measured diameters were more than 2 SDs above the average in normal volunteers, and abnormally small measurements were found in the patients with atrophy.

Adult↗

PubMedDate not supplied

Uncovertebral and facet joint dislocations in cervical articular pillar fractures: CT evaluation.

Computed tomographic (CT) scans and plain radiographs of 21 patients with surgically treated fractures or dislocations of the cervical spine were reviewed. CT effectively demonstrated the locked or perched facets and half of the 13 articular pillar fractures. The fracture lines through the articular pillar were difficult to detect in some cases or to distinguish from a facet joint in others. However, distraction of an adjacent uncovertebral or facet joint was demonstrated by CT in each case of articular pillar fracture or locked or perched facet. Therefore, CT demonstration of a distracted facet or uncovertebral joint is an indirect sign of an unstable fracture or of a dislocation that may be more readily recognized on plain radiographs or pluridirectional tomograms.

Cervical Vertebrae↗

PubMedDate not supplied

The hippocampus.

Explore the source record for details and available documents.

Hippocampus↗