A PHANTOM STUDY TO ASSESS THE ACCURACY OF STEREOTAXIC LOCALIZATION, USING T1-WEIGHTED MAGNETIC-RESONANCE-IMAGING WITH THE LEKSELL STEREOTAXIC SYSTEM

THIS PHANTOM STUDY assesses the accuracy of stereotactic localization using the Leksell G frame (Elekta Instruments AB, Stockholm, Sweden) w ith T1-weighted magnetic resonance imaging (Siemens 1.5 T Magnetom; Er langen, Germany). The coordinates of an array of solid perspex rods we re determined and compared with measured values in a series of transve rse, coronal, and sagittal images. The maximum absolute errors observe d (X = 2.7 mm, Y = 7.0 mm, Z = 8.0 mm) were discouraging. However, the more reasonable mean errors (X = 0.4 mm, Y = 0.7 mm, Z = 1.3 mm) refl ect considerable variation in accuracy throughout the volume assessed and limitation of maximum errors to specific areas. We present details of the spatial variation and discuss possible mechanisms for improvin g accuracy. The overall results are of direct relevance only to the sc anner used. These results are, however, an indication of the need to a pproach with caution stereotactic localization using magnetic resonanc e imaging and to emphasize the requirement for quality assurance and f or a comprehensive study of the scanner's characteristics.