MR imaging and cardiac pacemakers: in-vitro evaluation and in-vivo studies in 51 patients at 0.5 T.
OBJECTIVE
To evaluate the safety and feasibility of magnetic resonance (MR) imaging at 0.5 T in patients with implanted cardiac pacemakers.


METHODS
Twenty-one models of pacemakers and 44 pacemaker electrodes were exposed to in vitro MR imaging with continuous registration of pacemaker output and temperature at the lead tip. Prior to MR imaging examination, pacemakers were programmed to an asynchronous mode (A00, V00, or D00). Pacemakers were examined before and after MR imaging. Forty-four patients with implanted pacemakers underwent 51 MR imaging examinations under cardiologic surveillance, continuous electrocardiography, pulse oximetry, and capnographic monitoring.


RESULTS
MR imaging was safely performed in all patients. None of the pacemakers displayed a pacing dysfunction at MR imaging. No changes occurred in the programmed parameters in any device tested in vivo or in vitro. Maximum increases in the temperature at the lead tips were 8.90 degrees C at a specific absorption rate (SAR) of 0.6 W/kg and 23.50 degrees C under a worst-case radio-frequency (RF) heating condition with an SAR of 1.3 W/kg.


CONCLUSIONS
MR imaging at 0.5 T can be safely performed in patients with implanted pacemakers in carefully selected clinical circumstances when appropriate strategies (programming to an asynchronous mode, adequate monitoring techniques, limited RF exposure) are used.
Sommer
T
T
Dept. of Radiology, University of Bonn, Sigmund-Freud-Str 25, 53127 Bonn, Germany. t.sommer@uni-bonn.de
Vahlhaus
C
C
Lauck
G
G
von Smekal
A
A
Reinke
M
M
Hofer
U
U
Block
W
W
Träber
F
F
Schneider
C
C
Gieseke
J
J
Jung
W
W
Schild
H
H
D019296:Capnography; D000075202:Contraindications; D004562:Electrocardiography; D004566:Electrodes / Q000706:statistics & numerical data; D019544:Equipment Failure Analysis / Q000379:methods / Q000706:statistics & numerical data; D005240:Feasibility Studies; D006358:Hot Temperature; D006801:Humans; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data; D010092:Oximetry; D010138:Pacemaker, Artificial / Q000009:adverse effects / Q000706:statistics & numerical data; D011446:Prospective Studies; D012449:Safety