State-of-the-art imaging for glioma surgery

Niels Verburg,Philip C De Witt Hamer

doi:10.1007/s10143-020-01337-9

Abstract

Diffuse gliomas are infiltrative primary brain tumors with a poor prognosis despite multimodal treatment. Maximum safe resection is recommended whenever feasible. The extent of resection (EOR) is positively correlated with survival. Identification of glioma tissue during surgery is difficult due to its diffuse nature. Therefore, glioma resection is imaging-guided, making the choice for imaging technique an important aspect of glioma surgery. The current standard for resection guidance in non-enhancing gliomas is T2 weighted or T2w-fluid attenuation inversion recovery magnetic resonance imaging (MRI), and in enhancing gliomas T1-weighted MRI with a gadolinium-based contrast agent. Other MRI sequences, like magnetic resonance spectroscopy, imaging modalities, such as positron emission tomography, as well as intraoperative imaging techniques, including the use of fluorescence, are also available for the guidance of glioma resection. The neurosurgeon’s goal is to find the balance between maximizing the EOR and preserving brain functions since surgery-induced neurological deficits result in lower quality of life and shortened survival. This requires localization of important brain functions and white matter tracts to aid the pre-operative planning and surgical decision-making. Visualization of brain functions and white matter tracts is possible with functional MRI, diffusion tensor imaging, magnetoencephalography, and navigated transcranial magnetic stimulation. In this review, we discuss the current available imaging techniques for the guidance of glioma resection and the localization of brain functions and white matter tracts.

Highlights

Surgical resection is the first treatment in the majority of patients with a diffuse glioma
This study clearly shows the benefit of Diffusion tensor imaging (DTI) tractography in glioma resection, one must take into account that 63% of patients in the control group had poor clinical condition
How can imaging aid glioma surgery? We know gliomas are widespread in the brain by the time of diagnosis, so a curative resection is not possible [14]

Summary

Introduction

Surgical resection is the first treatment in the majority of patients with a diffuse glioma. A more extensive resection resulted in a lower complication rate (18% versus 26%, p = 0.04), which reflects, according to the authors, the increased use of DCS and imaging to visualize brain functions and white matter tracts. In non-enhancing glioma, multiple retrospective studies report improved complete resection rates (14 to 19%) of T2w or FLAIR abnormalities using iMRI [58, 63, 67]. Fluorescence-guided surgery is not limited by brain shift or navigation inaccuracy, making it a suitable technique to achieve GTR of contrast enhancement in high-grade gliomas. In an RCT comparing resection with and without pre-operative DTI in 214 patients with diffuse glioma involving the pyramidal tract, the use of DTI in patients with enhancing glioma resulted in a higher complete resection rate (74.4% versus 33.3%, p < 0.001), 6-month good clinical condition (70.0% versus 36.8%, p = 0.001), and improved median OS (21.2 versus 14.0 months, p = 0.048). IfMRI is not likely to replace DCS, iDTI has the potential to increase the safety of non-awake surgery

Discussion

Findings

Compliance with ethical standards