Intraoperative methods to maximize gliomas resection: a review of both established and novel techniques

Among primary central nervous system tumors, gliomas are the most frequent malignant type of tumor in adults, and the extent of resection has been strongly correlated with better survival rates and functional outcomes. However, it is difficult to recognize intraoperatively the tumor margins only based on the experience of the surgeon. Thus, there have been several intraoperative methods that can help the neurosurgeon in gross tumor resection. These methods can be divided into two categories: imaging-based techniques, such as intraoperative magnetic resonance imaging (iMRI), and intraoperative ultrasound (ioUS), and molecular-based methods such as fluorescence-guided surgery, desorption electrospray mass spectrometry (DESI-MS), Raman spectroscopy, and intraoperative flow cytometry (iFC). Intraoperative MRI, fluorescence-based techniques, and ioUS are well-studied methods, each of which has advantages and limitations. To deal with their known limitations, efforts have been made to combine these methods and to develop new methods such as DESI-MS. Raman spectroscopy, and iFC. Herein, we review the current methods and discuss novel promising findings.