MR-guided stereotactic neurosurgery--comparison of fiducial-based and anatomical landmark transformation approaches.
For application in magnetic resonance (MR) guided stereotactic neurosurgery, two methods for transformation of MR-image coordinates in stereotactic, frame-based coordinates exist: the direct stereotactic fiducial-based transformation method and the indirect anatomical landmark method. In contrast to direct stereotactic MR transformation, indirect transformation is based on anatomical landmark coregistration of stereotactic computerized tomography and non-stereotactic MR images. In a patient study, both transformation methods have been investigated with visual inspection and mutual information analysis. Comparison was done for our standard imaging protocol, including t2-weighted spin-echo as well as contrast enhanced t1-weighted gradient-echo imaging. For t2-weighted spin-echo imaging, both methods showed almost similar and satisfying performance with a small, but significant advantage for fiducial-based transformation. In contrast, for t1-weighted gradient-echo imaging with more geometric distortions due to field inhomogenities and gradient nonlinearity than t2-weighted spin-echo imaging, mainly caused by a reduced bandwidth per pixel, anatomical landmark transformation delivered markedly better results. Here, fiducial-based transformation yielded results which are intolerable for stereotactic neurosurgery. Mean Euclidian distances between both transformation methods were 0.96 mm for t2-weighted spin-echo and 1.67 mm for t1-weighted gradient-echo imaging. Maximum deviations were 1.72 mm and 3.06 mm, respectively.
Department of Stereotaxy and Functional Neurosurgery, University of Cologne, Cologne, Germany. stefan.hunsche@uk-koeln.de
S
S
Hunsche
D
D
Sauner
M
M
Maarouf
M
M
Hoevels
K
K
Luyken
O
O
Schulte
K
K
Lackner
V
V
Sturm
H
H
Treuer
D000465:Algorithms; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D038361:Neuronavigation / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013238:Stereotaxic Techniques; D013382:Subtraction Technique; D025321:Surgery, Computer-Assisted / Q000379:methods*