A team of researchers at Privolzhsky Research Medical University (Nizhny Novgorod, Russia) and the Institute of Applied Physics (also in Nizhny Novgorod) has developed a system based on optical coherence tomography (OCT) imaging to diagnose malignant brain tumors (gliomas) during surgery. In their study, the researchers obtained images of brain tissue that clearly show the differences between malignant and healthy cells, which could someday help to simplify tumor removal operations and make them more effective. 

Glioma is one of the most common diseases of the central nervous system. The difficulty of its treatment related to the fact that the tumor sometimes "grows into" the white substance and has no clear boundaries. The researchers are using OCT imaging, whose principle of operation resembles ultrasound diagnostics, to determine the tumor boundaries. However, the light wave penetrates the tissue by 1 to 2 mm, and then, depending on the structure, reflects with varying intensity. Based on the data obtained, the device creates an image of the brain.  

"OCT can be used to diagnose various tissues," says Alexander Moiseev, senior researcher at the highly sensitive optical measurement laboratory at the Institute of Applied Physics. "Our task is to identify the typical characters of tissues and learn how to systematize them." 

The researchers have analyzed more than 300 images of tissue samples taken from patients during tumor removal and biopsy procedures, and classified the differences between malignant and healthy cells. The main criterion is the intensity of the OCT signal.  

"Light penetrates healthy brain tissue shallowly and dissipates very well. Therefore, we receive an intense signal from the white substance. Tumor cells are more fragmented, which is why the light goes farther, and the signal is less intense," explains Konstantin Yashin, neurosurgeon at the University Hospital of the Research Medical University. Compared with ultrasound or MRI, OCT has a higher resolution. Therefore, scientists have identified an additional criterion for image analysis—the homogeneity of the tissues structure. 

At the moment, the researchers are carrying out the project to increase the information content of OCT in in vivo studies—they are working to improve the quality of the signal, as well as working on a special catheter for biopsy. 

Full details of the work appear in the journal Frontiers in Oncology.