Objectives: Intraoperative magnetic resonance imaging is a unique tool for visualizing structures during resection and/or for updating any kind of neuronavigation that might be hampered as a result of brain shift during surgery. Advanced MRI techniques such as perfusion-weighted imaging have already proven to be important in the initial diagnosis preoperatively, but can also help to differentiate between tumor and surgically induced changes intraoperatively. Commonly used methods to visualize brain perfusion include contrast agent administration and are therefore somewhat limited. One method that uses blood as an internal contrast medium is arterial spin labeling (ASL), which might represent an attractive alternative.
Materials and methods: Ten healthy volunteers were examined using three different scanners and coils within 1 h (3T Achieva MRI using 32-channel head coil, 1.5T Achieva MRI using a 6-channel head coil, 1.5 Intera Scanner using 2 surface coils, Philips, Best, The Netherlands) and quantitative CBF values were calculated and compared between the different setups. Additionally, in eight patients with glioblastoma multiforme, ASL was used pre-, intra-, and postoperatively to define tumor tissue and the extent of resection in comparison to structural imaging.
Results: A high correlation (r = 0.91-0.96) was found between MRI scanners and coils used. ASL was as reliable as conventional MR imaging if complete resection was already achieved, but additionally provided valuable information regarding residual tumor tissue in one patient.
Conclusions: Intraoperative arterial spin-labeling is a feasible, reproducible, and reliable tool to map CBF in brain tumors and seems to give beneficial information compared to conventional intraoperative MR imaging in partial resection.
Keywords: ASL; Arterial spin labeling; Intraoperative; Monitoring; Perfusion.