Intraoperative quantitative measurement of brain tumor stiffness and intracranial pressure assessment using ultrasound shear wave elastography

Abstract

Ultrasonography is proving to be an invaluable tool in brain surgery. Recently, new ultrasonic modalities called shear wave elastography (SWE) enabled living tissue assessment of stiffness. SWE is routinely used for breast or liver diseases, but brain data are missing. We aim to characterize elasticity of normal brain and brain tumors by using SWE and to study if there is a relationship between SWE and intracranial pressure (ICP). Improving quality of brain tumor resection and predict brain swelling are major concerns for neurosurgeons. A clinical study was undertaken, including normal brain and tumors data collected from intraoperative SWE. The aim is to improve shear wave imaging for brain tissue investigation by correlating in vivo stiffness data and histology. At the same time ICP was studied, first ex vivo and then during in vivo surgery, to observe brain swelling by using SWE. Shear waves were generated by using ultrasonic acoustic radiation force and imaged in real-time by an ultrafast ultrasound scanner up to 20 000 frames/s. This study demonstrates that there are significant differences in elasticity among the most common types of brain tumors. We show that SWE could help for diagnosis during tumor resection by distinguishing benign tumors from malignant tumors (AUROC: 0.77, p<10−4). Regarding pressure measurements, stiffness was found increasing with the pressure both ex vivo and in vivo. This study present great perspective for SWE to ensure grade differentiation and full tumor removal.