Differentiation between glioma tumor tissue and normal cerebral tissue using Diffuse Reflectance Spectroscopy (DRS) on surgical tissue samples ex-vivo

Background: Diffuse reflectance spectroscopy is an optically based technique which measures the amount of diffusely reflected light after it has undergone multiple scattering and absorption events within the tissue. Each DRS spectrum therefore has a specific 'optical fingerprint' reflecting the composition and morphology of the tissue within the probing volume. The technology is easily built into very small instruments that can be fused with regularly used surgical equipment. DRS has previously been widely investigated for the purpose of margin assessment in other regions of the body.

Aim & Hypothesis: The primary goal is to show the feasibility of applying optical tissue sensing using diffuse reflectance spectroscopy (DRS) to differentiate healthy cerebral tissue from tumorous tissue in ex vivo human tissue samples. This will be a basis for further development of surgical equipment able to identify the margin between healthy brain tissue and tumor tissue intraoperatively.

Method: Using DRS we aim to determine spectroscopy thresholds that enables differentiation of cerebral tissue from different forms of tumor tissue. We aim to determine these thresholds by collecting DRS data on ex vivo brain and tumor samples. The tumor samples will be part of the normal extraction of tissue during tumor surgeries and the non tumorous tissue can be extracted in temporal/frontal lobe resections as well as epilepsy surgery, where non tumorous brain tissue is to be removed. The DRS measurements are performed in direct connection to the extraction of tissue during surgery, and the tissue is thereafter sent to the pathologist according to standard clinical procedures. No extra tissue will need to be resected for the purpose of this study. Based on the experiments we will propose a theoretical model for differentiating normal cerebral tissue from tumor tissue in humans for use during surgery.

Inclusion Criteria:

• Patients undergoing surgical resection of glial tumor or epileptic focus

Exclusion Criteria:

• Unable to give informed consent

All patients undergoing surgical resection of glial tumors or non-neoplastic cerebral lesions at Karolinska University Hospital