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Temperature measurement on neurological pulse generators during MR scans.

Kainz W, Neubauer G, Uberbacher R, Alesch F, Chan DD - Biomed Eng Online (2002)

Bottom Line: Temperature increases in other locations were low compared to the one at the lead tip.The measured temperature increase of 2.1 degrees C can not be considered as harmful to the patient.Comparison with the results of other studies revealed the avoidance of loops as a practical method to reduce heating during MRI procedures.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mobile Communications Safety, ARC Seibersdorf Research, Austria. kainz@gmx.com

ABSTRACT
According to manufacturers of both magnetic resonance imaging (MRI) machines, and implantable neurological pulse generators (IPGs), MRI is contraindicated for patients with IPGs. A major argument for this restriction is the risk to induce heat in the leads due to the electromagnetic field, which could be dangerous for the surrounding brain parenchyma. The temperature change on the surface of the case of an ITREL-III (Medtronic Inc., Minneapolis, MN) and the lead tip during MRI was determined. An anatomical realistic and a cubic phantom, filled with phantom material mimicking human tissue, and a typical lead configuration were used to imitate a patient who carries an IPG for deep brain stimulation. The measurements were performed in a 1.5 T and a 3.0 T MRI. 2.1 degrees C temperature increases at the lead tip uncovered the lead tip as the most critical part concerning heating problems in IPGs. Temperature increases in other locations were low compared to the one at the lead tip. The measured temperature increase of 2.1 degrees C can not be considered as harmful to the patient. Comparison with the results of other studies revealed the avoidance of loops as a practical method to reduce heating during MRI procedures.

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Related in: MedlinePlus

Temperature at the lead tip as a function of time for two different FOV's (FOV over the breast: 300 to 1007 seconds; FOV over the head: 1434 to 2141 seconds)
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Figure 3: Temperature at the lead tip as a function of time for two different FOV's (FOV over the breast: 300 to 1007 seconds; FOV over the head: 1434 to 2141 seconds)

Mentions: It could be shown that the temperature inside the MRI tube was about 1°C higher than the outside. This indicated a slight and slow overlay of the temperature increase. But due to slow temperature transients of the phantom liquid this temperature overlay was only delayed and had no significant contribution to any temperature increase of metallic parts of the implant within the phantom liquid. The measured temperature increase of the implant itself was a modest value. An increase of about 0.25°C was shown. But at the lead tip a higher temperature increase was found. If the field of view was put over the implant the temperature increased about 1.8°C. With the FOV over the lead tip, an increase of 2.1°C was measured. Figure 3 shows the temperature increase versus time. Remarkable was the short increase and decrease time of about 20 seconds. This short time constant was possibly due to the small mass of the lead tip. The induced RF current dissipated in the tissue and heated the surrounding tissue and the lead tip.


Temperature measurement on neurological pulse generators during MR scans.

Kainz W, Neubauer G, Uberbacher R, Alesch F, Chan DD - Biomed Eng Online (2002)

Temperature at the lead tip as a function of time for two different FOV's (FOV over the breast: 300 to 1007 seconds; FOV over the head: 1434 to 2141 seconds)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC130994&req=5

Figure 3: Temperature at the lead tip as a function of time for two different FOV's (FOV over the breast: 300 to 1007 seconds; FOV over the head: 1434 to 2141 seconds)
Mentions: It could be shown that the temperature inside the MRI tube was about 1°C higher than the outside. This indicated a slight and slow overlay of the temperature increase. But due to slow temperature transients of the phantom liquid this temperature overlay was only delayed and had no significant contribution to any temperature increase of metallic parts of the implant within the phantom liquid. The measured temperature increase of the implant itself was a modest value. An increase of about 0.25°C was shown. But at the lead tip a higher temperature increase was found. If the field of view was put over the implant the temperature increased about 1.8°C. With the FOV over the lead tip, an increase of 2.1°C was measured. Figure 3 shows the temperature increase versus time. Remarkable was the short increase and decrease time of about 20 seconds. This short time constant was possibly due to the small mass of the lead tip. The induced RF current dissipated in the tissue and heated the surrounding tissue and the lead tip.

Bottom Line: Temperature increases in other locations were low compared to the one at the lead tip.The measured temperature increase of 2.1 degrees C can not be considered as harmful to the patient.Comparison with the results of other studies revealed the avoidance of loops as a practical method to reduce heating during MRI procedures.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mobile Communications Safety, ARC Seibersdorf Research, Austria. kainz@gmx.com

ABSTRACT
According to manufacturers of both magnetic resonance imaging (MRI) machines, and implantable neurological pulse generators (IPGs), MRI is contraindicated for patients with IPGs. A major argument for this restriction is the risk to induce heat in the leads due to the electromagnetic field, which could be dangerous for the surrounding brain parenchyma. The temperature change on the surface of the case of an ITREL-III (Medtronic Inc., Minneapolis, MN) and the lead tip during MRI was determined. An anatomical realistic and a cubic phantom, filled with phantom material mimicking human tissue, and a typical lead configuration were used to imitate a patient who carries an IPG for deep brain stimulation. The measurements were performed in a 1.5 T and a 3.0 T MRI. 2.1 degrees C temperature increases at the lead tip uncovered the lead tip as the most critical part concerning heating problems in IPGs. Temperature increases in other locations were low compared to the one at the lead tip. The measured temperature increase of 2.1 degrees C can not be considered as harmful to the patient. Comparison with the results of other studies revealed the avoidance of loops as a practical method to reduce heating during MRI procedures.

Show MeSH
Related in: MedlinePlus