Optimal Scan Parameters Pre/Postoperation?

[ggilmore]

Hi LEAD-DBS Team,

I am curious to know if there are “ideal” postoperative MRI scan parameter settings for best localization of electrodes. Our center currently follows the recommendations set by Medtronic (SAR to 0.1W/kg).

I have the potential to change our current postoperative MRI scan parameters. In an ideal world (without SAR restriction) what would be the best MRI scan parameters that would optimize localization with LEAD-DBS?

Our center uses a 1.5T MRI scanner.

Thank you,

Greydon

[andreashorn]

Hi Greydon,

I fear we are not the best people to ask here. Of course, general imaging principles apply: The better the resolution and signal to noise ratio, the more accurate the results may be.
Maybe you can get some insight here: http://www.ncbi.nlm.nih.gov/pubmed/25113409

In any case, I personally prefer T2 sequences over T1 sequences since they show the STN. If possible, 3D sequences with high resolution are optimal. However, more “clinical” acquisitions with high in-plane resolution and larger slice thicknesses are also okay. Up to three post-op sequences can be used in Lead-DBS in combination, e.g. an axial, coronar and saggital acquisition.

Hope this helps,

best, Andy

[markus.fahlstrom]

Hi,

A quick response a couple of month late, and probably obsolete.

For some IPG and electrode combinations from the Medtronic portfolio, new restrictions applies. Check Medtronic MRI webpage, http://www.mrisurescan.com

For a quick summary, check zrinzio et al 2011 (https://www.researchgate.net/profile/Ludvic_Zrinzo/publication/51569875_Clinical_Safety_of_Brain_Magnetic_Resonance_Imaging_with_Implanted_Deep_Brain_Stimulation_Hardware_Large_Case_Series_and_Review_of_the_Literature/links/02bfe50cc9e3130cae000000.pdf)

The SAR limit is quite hard. 0.4 W/kg is of course better (see Zrinzo link). However, new restrictions makes it possible to use multi-ch head coil, which is preferable for SNR issues. If you have a siemens system, the SPACE sequences could be a good options for 3D resolution T2 images. However, haven’t optimized these protocols at home yet. Think they have a low flip angle and low SAR/B1rms.

MPRAGE is always nice to have post-op. Good 3D image, with no SAR/B1rms issues.
Did a small survey, and B1rms 2 uT, correspond to about mean 0.4-0.5 W/kg, probably good to know.

Post-operative restrictions might be changing fast coming years, be sure to check the latest guidelines from the corresponding manufactures website.

/Markus
MRI-Phycisist

[Author]

Posts