ON THE PROBLEM OF GEOMETRIC DISTORTION IN MAGNETIC-RESONANCE IMAGES FOR STEREOTAXIC NEUROSURGERY

In this paper, we discuss the issue of geometric distortion in magneti c resonance (MR) images used to plan stereotactic neurosurgical interv entions. We analyze the process for the case of Fourier transform imag ing and demonstrate that spatial misregistrations are fundamentally du e to two causes: deviations of the magnetic field from its ideal value and blood flow. This enables us to relate the causes of geometric dis tortion to the MR imaging system, the patient and the stereotactic loc alizer frame. Based on the general model, we propose model refinements and discuss methods for the quantification and correction of all caus es. The results of our calculations and experiments indicate that, usi ng the proposed corrections, MRI and MR angiography should be consider ed valuable and reliable acquisition modalities for the planning of st ereotactic neurosurgical interventions.