FUNCTIONAL MAGNETIC-RESONANCE-IMAGING IN A STEREOTAXIC SETUP

The localization of critical structures within the brain is important for the planning of therapeutic strategies. Functional MRI is capable to assess functional response of cortical structures to certain stimul i. The authors present two techniques for functional MRT (fMRI) in a s tereotactic set-up. The skull of the patients has been immobilized for stereotactic treatment planning either with a self developed stereota ctic ceramic frame and bony fixation or with an individual precision m ask system made of light cast. It has been shown that this frame does not produce any image distortion. fMRI was performed using a modified FLASH sequence on a conventional 1.5 T MRI scanner with a specially de veloped linear polarized head coil. The imaging technique used was an optimized conventional 2D and 3D, first order how rephased, gradient e cho sequence (FLASH) with fat-suppression and reduce bandwidth (16-28 Hz/pixel) and TR = 80-120 ms, TE = 60 ms, hip angle = 40 degrees, matr ix = 128 x 128, FOV = 150-250 mm, slice-thickness = 2-5 mm, NEX = 1, a nd a total single scan time for one image of about 7 sec. The motor co rtex stimulation was achieved by touching each finger to thumb in a se quential, self-paced, and repetitive manner. Statistical parametric ma ps based on student's test were calculated, Pixels with a highly signi ficant signal increase (p < 0.001) are overlaid on T1w SE images. The primary motor and sensory cortex could be visualized with this method in all 10 patients that were imaged in this study. Due to tight fixati on of the patient's skull there have been no motion artifacts. These r esults show that functional MRT is feasible in an stereotactic set-up with an standard 1.5 T scanner. This is a prerequisite for the exact p re therapeutic assessment of the function of cortical centers. Copyrig ht (C) 1996 Elsevier Science Inc.