Optimal MRI methods for direct stereotactic targeting of the subthalamic nucleus and globus pallidus.
OBJECTIVE
Reliable identification of the subthalamic nucleus (STN) and globus pallidus interna (GPi) is critical for deep brain stimulation (DBS) of these structures. The purpose of this study was to compare the visibility of the STN and GPi with various MRI techniques and to assess the suitability of each technique for direct stereotactic targeting.


METHODS
MR images were acquired from nine volunteers with T2- and proton density-weighted (PD-W) fast spin echo, susceptibility-weighted imaging (SWI), phase-sensitive inversion recovery and quantitative T1, T2 and T2* mapping sequences. Contrast-to-noise ratios (CNR) for the STN and GPi were calculated for all sequences. Targeting errors on SWI were evaluated on magnetic susceptibility maps. The sequences demonstrating the best conspicuity of DBS target structures (SWI and T2*) were then applied to ten patients with movement disorders, and the CNRs for these techniques were assessed.


RESULTS
SWI offers the highest CNR for the STN, but standard PD-W images provide the best CNR for the pallidum. Susceptibility maps indicated that the GPi margins may be shifted slightly on SWI, although no shifts were seen for the STN.


CONCLUSIONS
SWI may improve the visibility of the STN on pre-operative MRI, potentially improving the accuracy of direct stereotactic targeting.
O'Gorman
Ruth L
RL
Department of Neuroradiology, King's College Hospital, Denmark Hill, London, SE5 9RS, UK. ruth.ogorman@kcl.ac.uk
Shmueli
Karin
K
Ashkan
Keyoumars
K
Samuel
Michael
M
Lythgoe
David J
DJ
Shahidiani
Asal
A
Wastling
Stephen J
SJ
Footman
Michelle
M
Selway
Richard P
RP
Jarosz
Jozef
J
D000328:Adult; D005260:Female; D005917:Globus Pallidus / Q000000981:diagnostic imaging*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011859:Radiography; D012015:Reference Standards; D013238:Stereotaxic Techniques; D020531:Subthalamic Nucleus / Q000000981:diagnostic imaging*