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The Safety of Using Body-Transmit MRI in Patients with Implanted Deep Brain Stimulation Devices.

Kahan J, Papadaki A, White M, Mancini L, Yousry T, Zrinzo L, Limousin P, Hariz M, Foltynie T, Thornton J - PLoS ONE (2015)

Bottom Line: We compared the safety of cranial MRI in an in vitro model of bilateral DBS using both head-transmit and body-transmit coils.The position of the phantom relative to the body coil significantly impacted on electrode heating at 1.5T; however, the greatest heating observed in any position tested remained <1°C at this field strength.We conclude that (1) with our specific hardware and SAR-limited protocol, body-transmit cranial MRI at 1.5T does not produce heating exceeding international guidelines, even in cases of poorly positioned patients, (2) cranial MRI at 3T can readily produce heating exceeding international guidelines, (3) patients with ActivaPC Medtronic systems are safe to be recruited to future fMRI experiments performed under the specific conditions defined by our protocol, with no likelihood of confound by inappropriate stimulus delivery.

View Article: PubMed Central - PubMed

Affiliation: Sobell Department of Motor Neuroscience & Movement Disorders, UCL Institute of Neurology, London, United Kingdom.

ABSTRACT

Background: Deep brain stimulation (DBS) is an established treatment for patients with movement disorders. Patients receiving chronic DBS provide a unique opportunity to explore the underlying mechanisms of DBS using functional MRI. It has been shown that the main safety concern with MRI in these patients is heating at the electrode tips - which can be minimised with strict adherence to a supervised acquisition protocol using a head-transmit/receive coil at 1.5T. MRI using the body-transmit coil with a multi-channel receive head coil has a number of potential advantages including an improved signal-to-noise ratio.

Study outline: We compared the safety of cranial MRI in an in vitro model of bilateral DBS using both head-transmit and body-transmit coils. We performed fibre-optic thermometry at a Medtronic ActivaPC device and Medtronic 3389 electrodes during turbo-spin echo (TSE) MRI using both coil arrangements at 1.5T and 3T, in addition to gradient-echo echo-planar fMRI exposure at 1.5T. Finally, we investigated the effect of transmit-coil choice on DBS stimulus delivery during MRI.

Results: Temperature increases were consistently largest at the electrode tips. Changing from head- to body-transmit coil significantly increased the electrode temperature elevation during TSE scans with scanner-reported head SAR 0.2W/kg from 0.45°C to 0.79°C (p<0.001) at 1.5T, and from 1.25°C to 1.44°C (p<0.001) at 3T. The position of the phantom relative to the body coil significantly impacted on electrode heating at 1.5T; however, the greatest heating observed in any position tested remained <1°C at this field strength.

Conclusions: We conclude that (1) with our specific hardware and SAR-limited protocol, body-transmit cranial MRI at 1.5T does not produce heating exceeding international guidelines, even in cases of poorly positioned patients, (2) cranial MRI at 3T can readily produce heating exceeding international guidelines, (3) patients with ActivaPC Medtronic systems are safe to be recruited to future fMRI experiments performed under the specific conditions defined by our protocol, with no likelihood of confound by inappropriate stimulus delivery.

No MeSH data available.


Related in: MedlinePlus

The fibre-optic temperature sensors positioned at the distal electrode contacts.The fine golden leads are the temperature probe optical fibres, whereas the grey leads with 4 visible metal contacts are the DBS electrode leads. Suture silk was used to ensure that the thermometer probes were in close thermal contact with the distal electrode contact surfaces, previously demonstrated to be the sites of greatest MRI-induced heating.
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pone.0129077.g003: The fibre-optic temperature sensors positioned at the distal electrode contacts.The fine golden leads are the temperature probe optical fibres, whereas the grey leads with 4 visible metal contacts are the DBS electrode leads. Suture silk was used to ensure that the thermometer probes were in close thermal contact with the distal electrode contact surfaces, previously demonstrated to be the sites of greatest MRI-induced heating.

Mentions: The temperature was recorded simultaneously from four loci in the phantom using a 4 channel fibre-optic temperature thermometer (Neoptix ReFlex—Neoptix, Québec, Canada) based on gallium arsenide (GaAs) semiconductor crystal technology (sampling rate = 1Hz). Temperature probes were located at the distal electrode contacts (one for each electrode lead—see Figs 2 and 3), the IPG case, and the centre of the phantom ‘head’ region, remote from the electrode contacts, this location providing a control recording of background temperature changes.


The Safety of Using Body-Transmit MRI in Patients with Implanted Deep Brain Stimulation Devices.

Kahan J, Papadaki A, White M, Mancini L, Yousry T, Zrinzo L, Limousin P, Hariz M, Foltynie T, Thornton J - PLoS ONE (2015)

The fibre-optic temperature sensors positioned at the distal electrode contacts.The fine golden leads are the temperature probe optical fibres, whereas the grey leads with 4 visible metal contacts are the DBS electrode leads. Suture silk was used to ensure that the thermometer probes were in close thermal contact with the distal electrode contact surfaces, previously demonstrated to be the sites of greatest MRI-induced heating.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4465697&req=5

pone.0129077.g003: The fibre-optic temperature sensors positioned at the distal electrode contacts.The fine golden leads are the temperature probe optical fibres, whereas the grey leads with 4 visible metal contacts are the DBS electrode leads. Suture silk was used to ensure that the thermometer probes were in close thermal contact with the distal electrode contact surfaces, previously demonstrated to be the sites of greatest MRI-induced heating.
Mentions: The temperature was recorded simultaneously from four loci in the phantom using a 4 channel fibre-optic temperature thermometer (Neoptix ReFlex—Neoptix, Québec, Canada) based on gallium arsenide (GaAs) semiconductor crystal technology (sampling rate = 1Hz). Temperature probes were located at the distal electrode contacts (one for each electrode lead—see Figs 2 and 3), the IPG case, and the centre of the phantom ‘head’ region, remote from the electrode contacts, this location providing a control recording of background temperature changes.

Bottom Line: We compared the safety of cranial MRI in an in vitro model of bilateral DBS using both head-transmit and body-transmit coils.The position of the phantom relative to the body coil significantly impacted on electrode heating at 1.5T; however, the greatest heating observed in any position tested remained <1°C at this field strength.We conclude that (1) with our specific hardware and SAR-limited protocol, body-transmit cranial MRI at 1.5T does not produce heating exceeding international guidelines, even in cases of poorly positioned patients, (2) cranial MRI at 3T can readily produce heating exceeding international guidelines, (3) patients with ActivaPC Medtronic systems are safe to be recruited to future fMRI experiments performed under the specific conditions defined by our protocol, with no likelihood of confound by inappropriate stimulus delivery.

View Article: PubMed Central - PubMed

Affiliation: Sobell Department of Motor Neuroscience & Movement Disorders, UCL Institute of Neurology, London, United Kingdom.

ABSTRACT

Background: Deep brain stimulation (DBS) is an established treatment for patients with movement disorders. Patients receiving chronic DBS provide a unique opportunity to explore the underlying mechanisms of DBS using functional MRI. It has been shown that the main safety concern with MRI in these patients is heating at the electrode tips - which can be minimised with strict adherence to a supervised acquisition protocol using a head-transmit/receive coil at 1.5T. MRI using the body-transmit coil with a multi-channel receive head coil has a number of potential advantages including an improved signal-to-noise ratio.

Study outline: We compared the safety of cranial MRI in an in vitro model of bilateral DBS using both head-transmit and body-transmit coils. We performed fibre-optic thermometry at a Medtronic ActivaPC device and Medtronic 3389 electrodes during turbo-spin echo (TSE) MRI using both coil arrangements at 1.5T and 3T, in addition to gradient-echo echo-planar fMRI exposure at 1.5T. Finally, we investigated the effect of transmit-coil choice on DBS stimulus delivery during MRI.

Results: Temperature increases were consistently largest at the electrode tips. Changing from head- to body-transmit coil significantly increased the electrode temperature elevation during TSE scans with scanner-reported head SAR 0.2W/kg from 0.45°C to 0.79°C (p<0.001) at 1.5T, and from 1.25°C to 1.44°C (p<0.001) at 3T. The position of the phantom relative to the body coil significantly impacted on electrode heating at 1.5T; however, the greatest heating observed in any position tested remained <1°C at this field strength.

Conclusions: We conclude that (1) with our specific hardware and SAR-limited protocol, body-transmit cranial MRI at 1.5T does not produce heating exceeding international guidelines, even in cases of poorly positioned patients, (2) cranial MRI at 3T can readily produce heating exceeding international guidelines, (3) patients with ActivaPC Medtronic systems are safe to be recruited to future fMRI experiments performed under the specific conditions defined by our protocol, with no likelihood of confound by inappropriate stimulus delivery.

No MeSH data available.


Related in: MedlinePlus