[Magnetic resonance imaging of the brain in patients with cardiac pacemakers. Experimental and clinical investigations at 1.5 Tesla]. / MRT-Untersuchungen des Hirns bei Patienten mit implantierten Herzschrittmachern. Experimentelle und klinische Untersuchungen an einem 1.5 Tesla-System.
Rofo
; 177(5): 731-44, 2005 May.
Article
in De
| MEDLINE
| ID: mdl-15871088
ABSTRACT
PURPOSE:
In-vitro and In-vivo evaluation of feasibility and safety of MRI of the brain at 1.5 T in patients with implanted pacemakers (PM). MATERIALS ANDMETHODS:
24 PM models and 45 PM electrodes were tested In-vitro with respect to translational forces, heating of PM leads, behaviour of reed switch (activated vs. deactivated) and function at a 1.5 T MRI-system (actively shielded, maximum field gradient 30 mT/m; rise time 150 T/m/s). Based on these results, 63 MRI examinations in 45 patients with implanted PM were performed. Prior to MRI the PM were re-programmed in an asynchronous mode. The maximum SAR of MRI-sequences was limited to 1.2 W/kg. Continuous monitoring of ECG and pulse oximetry was performed during MRI. PM inquiry was performed prior to MRI, immediately after MRI and -- to assess long-term damages -- three months after the MRI exams, including determination of stimulation thresholds to assess potential thermal myocardial injuries at the lead tips.RESULTS:
Translational forces (F (max) < or = 560 mN) and temperature increase (DeltaT (max) < or = 2.98 degrees C) were in a range which does not represent a safety concern from a biophysical point of view. No changes to the programmed parameters of the PM or damage of PM components were observed neither In-vitro (n = 0/24) nor In-vivo (n = 0/63). Despite the strong magnetic field, the reed switch remained deactivated in 54 % (13/24) of the cases during In-vitro simulated MRI exams of the brain. All patient studies (n = 63/63) could be completed without any complications. Atrial and ventricular stimulation thresholds (expressed as pulse duration at 2-fold rheobase) did not change significantly immediately post-MRI nor in the 3 months follow-up (pre-MRI 0.17 ms +/- 0.13 ms, post-MRI 0.18 ms +/- 0.14 ms, 3 months follow-up 0.17 ms +/- 0.12 ms).CONCLUSION:
MRI of the brain at 1.5 Tesla can be safely performed in carefully selected clinical circumstances when appropriate strategies are used (re-programming the PM to an asynchronous mode, continuous monitoring of ECG and pulse oximetry, limiting the SAR value of the MRI sequences, cardiological stand-by). Based on these studies, implanted PM should not longer be regarded as an absolute contraindication for MRI at 1.5 T.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Pacemaker, Artificial
/
Burns, Electric
/
Magnetic Resonance Imaging
/
Risk Assessment
/
Equipment Failure Analysis
/
Equipment Failure
/
Heart Injuries
Type of study:
Diagnostic_studies
/
Etiology_studies
/
Prognostic_studies
/
Risk_factors_studies
Limits:
Humans
Language:
De
Journal:
Rofo
Year:
2005
Document type:
Article