Ultrasound Elastography and Ultrasentive Doppler for Surgery of Brain Tumors

Overview

Surgery for brain gliomas is usually guided by different imaging techniques including neuronavigation MRI and intraoperative ultrasound that do not allow visualization of the low-density peri-lesional tumor infiltration present in gliomas and from which the tumor recurs. Another important aspect in the management of glial tumors is the histological grade. The appearance of new vessels (called neo-angiogenesis) is one of the crucial steps in the life of these tumors, which signifies the transition to anaplasia. This neoangiogenesis is diagnosed during the anatomopathological analysis of the operative specimen, and may be suspected on preoperative MRI on the so-called infusion sequences. The objective of this project is to evaluate the potential of two ultrasound modalities - elastography and ultrasensitive Doppler - in helping the surgical management of brain tumors. Ultrasound elastography measures cerebral elasticity and thus indirectly the degree of tumor infiltration; while ultrasensitive Doppler measures intratumoral vascularization, and could therefore help in the diagnosis of tumor anaplasia.

Surgery for brain gliomas is usually guided by different imaging techniques including neuronavigation MRI and intraoperative ultrasound. Unfortunately, MRI and ultrasound do not allow visualization of the low-density peri-lesional tumor infiltration present in gliomas and from which the tumor recurs. Developing tools to identify this "peritumoral" infiltration zone is therefore a major issue in neuro-oncology. The consistency of brain tumors is a subjective criterion used in cerebral glioma surgery, the tumor area being firmer than the adjacent healthy brain. A pilot study was conducted from December 2012 to March 2014 by the Langevin Institute at La Pitié Salpêtrière. In this study, an intraoperative quantitative measurement of ultrasound elastography was performed on a cohort of patients with brain tumors. A significant difference between elasticity of low grade and high grade gliomas was found. However, in this study, no data on elasticity in a perilational infiltration zone is available. Another important aspect in the management of glial tumors is the histological grade. The appearance of new vessels (called neo-angiogenesis) is one of the crucial steps in the life of these tumors, which signifies the transition to anaplasia. This neoangiogenesis is diagnosed during the anatomopathological analysis of the operative specimen, and may be suspected on preoperative MRI on the so-called infusion sequences. The objective of this project is to evaluate the potential of two ultrasound modalities - elastography and ultrasensitive Doppler - in helping the surgical management of brain tumors, through intraoperative ultrasound. Ultrasound elastography measures cerebral elasticity and thus indirectly the degree of tumor infiltration; while ultrasensitive Doppler measures intratumoral vascularization, and can therefore help in the diagnosis of tumor anaplasia. Ultrasound elastography and ultrasensitive Doppler could enable us to more precisely target the more active tumoral territories (morphological criteria), to better identify the peri-lesional tumor infiltration in order to more precisely guide our resection procedure, and to provide additional information important for pathological analysis.