Safety of brain 3-T MR imaging with transmit-receive head coil in patients with cardiac pacemakers: pilot prospective study with 51 examinations.
OBJECTIVE
To evaluate the safety and feasibility of 3-T magnetic resonance (MR) imaging of the brain in patients with implanted cardiac pacemakers (PMs) by using a transmit-receive head coil.


METHODS
The study protocol was approved by the institutional review board. Signed informed consent was obtained from all subjects. In vitro testing at 3 T was performed with 32 PMs and 45 PM leads that were evaluated for force and torque (by using a floating platform) and radiofrequency (RF)-related heating by using a transmit-receive head coil (maximum specific absorption rate, 3.2 W/kg). Patient examinations at 3 T were performed in 44 patients with a cardiac PM and a strong clinical need; patients underwent a total of 51 MR examinations of the brain by using a transmit-receive head coil to minimize RF exposure of the PM system. An electrocardiograph and pulse oximetry were used for continuous monitoring during MR imaging. The technical and functional PM status was assessed prior to and immediately after MR imaging and at 3 months thereafter. Serum troponin I level was measured before and 12 hours after imaging to detect myocardial thermal injury. PM reprogramming was performed prior to MR imaging depending on the patient's intrinsic heart rate (< 60 beats per minute, asynchronous pacing; > or = 60 beats per minute, sense-only mode).


RESULTS
For in vitro testing, the maximum translational force was 2150 mN (mean, 374.38 mN +/- 392.75 [standard deviation]), and maximum torque was 17.8 x 10(-3) N x m (mean, [2.29 +/- 4.08] x 10(-3) N x m). The maximum temperature increase was 2.98 degrees C (mean, 0.16 degrees C +/- 0.45). For patient examinations, all MR examinations (51 of 51) were completed safely. There were no significant (P < .05) changes in lead impedance, pacing capture threshold level, or serum troponin I level.


CONCLUSIONS
MR imaging of the brain at 3 T in patients with a cardiac PM can be performed safely when dedicated safety precautions (including the use of a transmit-receive head coil) are taken.
Naehle
Claas P
CP
Department of Radiology, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany. cp@naehle.net
Meyer
Carsten
C
Thomas
Daniel
D
Remerie
Susann
S
Krautmacher
Carsten
C
Litt
Harold
H
Luechinger
Roger
R
Fimmers
Rolf
R
Schild
Hans
H
Sommer
Torsten
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain; D002648:Child; D004562:Electrocardiography; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D010092:Oximetry; D010138:Pacemaker, Artificial; D010865:Pilot Projects; D011446:Prospective Studies; D012449:Safety