ZIB

Hits per page

hits 1 - 2 | 2 hits

Sorting

Electronic Resource

Interactions of magnetic resonance imaging radio frequency magnetic fields with elongated medical implants (2000)

Smith, Chris D. ; Kildishev, Alexander V. ; Nyenhuis, John A. ; [et al.]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 87 (2000), S. 6188-6190

add to mindlist on the mindlist

Details

ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: Magnetic resonance imaging (MRI) is a well established diagnostic technique, one from which all patients should be able to benefit, including those with implanted medical devices. This paper describes an experimental and numerical study of the temperature rise near the ends of wires by the radio frequency (rf) field in MRI. These wires simulate long wires which may be part of a medical implant. Temperature rise as a function of time was measured for wires of different lengths and diameters in a phantom exposed to the 64 MHz rf field inside a MRI body coil. For wires with no or thin insulation, the maximal rise was about seven times background for a wire length of 20 cm; wires with longer and shorter lengths exhibited less temperature rise. The temperature rise was greater for wires with thicker insulation. Computer simulations using a quasistatic model are in reasonable agreement with the measurements on shorter wires. It is concluded that medical implants with long conducting lead wires may result in potentially unsafe temperature rise during MRI imaging. © 2000 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.372651

Permalink

Library	Location	Call Number	Volume/Issue/Year	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Electrophysiological Control of Ventricular Rate During Atrial Fibrillation (2000)

WANINGER, MATTHEW S. ; BOURLAND, JOE D. ; GEDDES, LESLIE A. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Pacing and clinical electrophysiology 23 (2000), S. 0

add to mindlist on the mindlist

Details

ISSN: 1540-8159

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Medicine

Notes: Thirteen anesthetized canine subjects (17–29 kg) were used to demonstrate that mild cervical left vagal stimulation could control ventricular rate effectively during atrial fibrillation (AF). Two studies are presented. The first study used six subjects to demonstrate the inverse relationship between (manually applied) left vagal stimulation and ventricular excitation (R wave) rate during AF. As left vagal stimulation frequency was increased, ventricular excitation rate decreased. In these studies, a left vagal stimulus frequency of 0–10 per second reduced the ventricular excitation rate from 〉 200/min to 〈 50/min. The decreasing ventricular excitation rate with increasing left vagal stimulation frequency was universal, occurring in all 26 trials with the six subjects. This fundamental principle was used to construct an automatic controller for use in the second study, in which seven subjects were used to demonstrate that ventricular rate can be brought to and maintained within a targeted range with the use of an automatic (closed-loop) controller. A 45-minute record of automatic ventricular rate control is presented. Similar records were obtained in all seven subjects.