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Volume 18 Supplement 1

19th Annual SCMR Scientific Sessions

  • Oral presentation
  • Open Access

RF induced heating of pacemaker/ICD lead-tips during MRI Scans at 1.5T and 3T: evaluation in cadavers

  • 2,
  • 2, 1,
  • 2,
  • 2,
  • 2,
  • 2 and
  • 2, 1
Journal of Cardiovascular Magnetic Resonance201618 (Suppl 1) :O121

https://doi.org/10.1186/1532-429X-18-S1-O121

  • Published:

Keywords

  • Temperature Difference
  • Right Ventricular
  • Tissue Perfusion
  • Temperature Probe
  • Human Cadaver

Background

Studies about the safety of MRI exams for patients with pacemakers/ICDs at 1.5T have been reported [Nazarian S., et al. Annals of internal medicine 155.7 (2011): 415-424.]. Of most concern is possible heating of the lead-tips in contact with the myocardium. Little is known about the relative safety of 3T MRI exams for these patients and in vivo lead-tip heating data is difficult, if not impossible, to obtain. Our objective was to measure lead-tip heating directly in human cadavers with pacemakers/ICDs at both 3.0T and 1.5T.

Methods

Cadavers (N = 5, 3 male, Table 1, part 1) with existing pacemakers had fiberoptic temperature probes implanted adjacent to right atrial (RA), right ventricular (RV) and/or abandoned lead-tips under x-ray guidance. Whole-body CT was used to estimate lead-tip to probe-tip distances. Cadavers were exposed to 15-minutes of 4 W/kg whole body SAR at both 1.5T and 3T (Siemens Avanto and Prisma) for five isocenter positions: 6 cm superior to the chin (LM1) and in four 15 cm increments inferior to LM1 (LM2 to LM5) in order to evaluate lead-tip heating as a function of the device's position relative to isocenter (i.e. different MRI exams). Maximum temperature increases at the lead-tip were reported as TMax (temperature difference between the baseline before the MRI sequence and peak heating after 15-minutes).
Table 1

Part 1 is the table that shows vital statistics of the cadavers. Part 2 is the table that shows the lead tip to probe tip distances

Part 1

Gender

Weight (kg)

Height (cm)

BMI

Age

   

Cadaver 1

Male

54

167

19.4

93

   

Cadaver 2

Female

36

147

16.7

99

   

Cadaver 3

Male

58

177

18.5

85

   

Cadaver 4

Male

45

172

15.2

93

   

Cadaver 5

Female

68

167

24.4

87

   

Part 2

Cadaver 1

Cadaver 2 RA lead

Cadaver 3

Cadaver 4 RA lead

Cadaver 4 RV lead

Cadaver 5 RA lead

Cadaver 5 RV lead

Cadaver 5 Abandoned lead

Lead tip to probe tip distance

6.4 mm

3.4 mm

10 mm

2 mm

9 mm

6.5 mm

7.6 mm

4 mm

Results

All temperature probes were ≤10 mm from the lead-tip (Table 1, part 2). Figure 1 shows TMax for 1.5T and 3T for each probe. Maximum heating was observed at the LM2 and LM3 isocenter positions for which the whole implant was inside the body transmit coil. TMax was >2C for 7 of 25 cases at 1.5T and for 12 of 25 cases at 3T, but never exceeded 4C.
Figure 1
Figure 1

T Max for each isocenter position. Cadavers 1 and 3 have single chamber pacemakers (RV leads); cadavers 2, 4, and 5 have dual chamber pacemakers (RA and RV lead). Cadaver 5 also had 10 abandoned leads. For single chamber pacemakers a temperature probe was placed at the lead-tip and the remaining temperature probes were placed in remote tissue for reference. For dual chamber pacemakers, the temperature probes were placed at the RA and RV lead-tips and two probes were placed in remote tissue for reference. For the cadaver with abandoned leads two temperature probes were placed close to the lead-tips connected to the pacemaker and one probe was placed close to lead-tip of one abandoned lead (ALT). Note that in cadaver 2 the RV temperature probe was not close enough to the RV lead-tip (accidentally partially withdrawn) to obtain temperature data.

Conclusions

These data do not indicate a substantial difference between lead-tip heating at 1.5T and 3T, nor do they indicate TMax>4C despite the lack of cooling due to tissue perfusion. Continued evaluation is warranted and on-going.

Authors’ Affiliations

(1)
Department of Bioengineering, University of California Los Angeles, Los Angeles, CA, USA
(2)
Department of Radiological Sciences, University of California Los Angeles, Los Angeles, CA, USA

Copyright

© Acikel et al. 2016

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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