Intra-operative, real-time, three-dimensional ultrasound assisted positioning of catheters in the microdialysis of glial tumours.

Microdialysis allows sampling of the extra cellular fluid of normal and pathological tissues. Accurate positioning of catheters in viable, representative tumour tissue is crucial for the accuracy and effectiveness of the technique. We have performed microdialysis with the aid of intra-operative three-dimensional ultrasonography (3D-US) to guide the placement of catheters in seven patients undergoing resection for supratentorial high-grade astrocytoma. The final position of the catheter tip membrane was confirmed by intra-operative ultrasound scanning. The accuracy of the spatial targeting was validated by pathological examination and the quality of the microdialysate was checked with ultra performance liquid chromatography-mass spectrometry. Our results indicate that intra-operative 3D-US can be used to correctly position catheters for microdialysis and allows adjustment to the catheters, when necessary, prior to the dialysis of viable target tumour tissue.