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Biomedical subjects

A Jesmanowicz

Publications and source records attributed to A Jesmanowicz.

61 records · Page 4Linked to original sources
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

High resolution MR imaging of glomus tumor.

High resolution magnetic resonance images of a surgically confirmed glomus tumor of the finger obtained with a surface coil are shown. Magnetic resonance has the potential to preoperatively evaluate soft tissue tumors of these regions which are poorly imaged by other modalities.

Female↗
PubMedDate not supplied

Functional magnetic resonance imaging in partial epilepsy.

Functional magnetic resonance imaging (FMRI) detects signal changes in brain that accompany regional changes in neuronal activity. In normal human brain, FMRI shows changes in signal in the postcentral gyrus or superior temporal gyrus that correlate with voluntary motor activity or language processing, respectively. The model used to explain the changes in signal linked temporally with cerebral activity is a reduction in cerebral capillary deoxyhemoglobin concentration due to the increased blood flow that accompanies neuronal activity in the cerebrum. FMRI has been used in normal subjects but not extensively in patients. To determine the feasibility of using FMRI to map cerebral functions in patients with partial epilepsy syndromes, we performed a pilot study, using FMRI to identify signal changes in motor and language areas in response to tasks that activate those areas. Signal changes in epilepsy patients approximated those observed in volunteers. We conclude that FMRI can be developed as a method for functional cerebral mapping in partial epilepsies.

Adult↗
PubMedDate not supplied

Planar-pair local coils for high-resolution magnetic resonance imaging, particularly of the temporomandibular joint.

The two-loop--one-gap loop--gap resonator (planar pair) has been investigated as a local receiving coil for high-resolution proton imaging at 1.5 T (63.8 MHz). Sensitivity contours were determined on the bench by measuring the voltage induced in the coil when it is placed on the surface of a tank containing 0.1-M NaCl, as a function of the coordinates and orientation of a radiating dipole inside the tank. Contours were obtained as a function of the diameter D of the two loops, and their separation d. For comparison, considerable data also were obtained for single-turn circular loops as a function of loop diameter. Coil quality factors, Q's, are reported in free space and the saline tank as a function of geometric parameters. Contours also were obtained using phantoms in a whole-body imager. Planar-pair coils couple to slabs of approximately (2D + d) X D cross section, and are superior to circular coils for imaging anatomic structures that are somewhat elongated. A particularly important feature of planar-pair local coils is that they are intrinsically isolated from the whole-body coil of the imager, and no special passive or active circuits are required when the whole-body coil is used for excitation. Planar-pair local coils have been optimized for imaging of the temporomandibular joint, and an image is shown.

Humans↗
PubMedDate not supplied

The cervical nerves and foramina: local-coil MR imaging.

A detailed study of the magnetic resonance (MR) appearance of the cervical nerves and neural foramina is presented. Using a "butterfly" local coil and a 1.5-T GE Signa MR system, the authors obtained 3-mm-thick axial, parasagittal, and 45 degrees oblique MR images of the cervical neural foramina in four normal volunteers. For the oblique images, subjects were rotated 45 degrees toward the right posterior oblique. Neural and vascular structures in the foramina were identified by correlation of the MR images with corresponding cryomicrotomic sections from four cadavers. The 45 degrees oblique images were more useful than axial or parasagittal images for demonstrating anatomic relations in the neural foramina. MR imaging with local coils demonstrates the complex anatomy of cervical neural foramina in various planes.

Adult↗