Real-time ultrasound navigation helps see brain shift


Brain tumour surgery has undergone significant changes in recent years thanks to new and improved tracking and imaging technologies. Now, ultrasound imaging can be used in real time to detect brain shift and improve surgical outcomes for operating room teams and their patients.

Every day, 27 Canadians are diagnosed with a brain tumour according to the Brain Tumour Foundation of Canada, ranging from malignant cancer to benign cysts. When surgery is required, one particular challenge in removing brain tumours is a phenomenon known as brain shift. This happens when the brain moves within the cranium once a surgeon has made a hole in the skull. Depending on the patient, and the length of the procedure in question, brain shift can be relatively significant.

During operations, surgeons rely on sophisticated navigation and tracking systems to locate tumours that may not be visible to the naked eye because they are either too small or located in a difficult-to-see area. These navigation systems typically rely on MRI or CT-scan data that was gathered prior to surgery when the pressure in the brain was normal.  As a result, these images do not reflect any potential brain shift.


Not having access to real-time images can lead to a number of potential issues. Portions of a tumour may be left behind, leading to additional treatment, such as chemotherapy or a second surgery. In worst case scenarios, the surgeon may actually remove healthy tissue, potentially leading to impairments that could have been avoided.

Intraoperative MRI technology – in which surgery is performed using real-time MRI imaging without the need to move the patient – has been a major milestone in advancing brain tumour removal. This technology is rarely available, however, largely because costs for purchasing and installation can run from $3 million and up. Currently, it is only available in a limited number of top medical facilities around the world.

Luckily, surgeons now have access to an effective and more affordable option with innovations such as the Stealth® Navigated Ultrasound. This add-on module for the widely-used StealthSation® platform allows surgeons to plug a guided ultrasound probe into a navigation system to look for tumours during surgery. This real-time, intraoperative ultrasound imaging can be combined with preoperative imaging in order to more accurately detect the extent of brain shift during surgery and assess the accuracy of the surgical procedure.


Unlike intraoperative MRI systems, guided ultrasound probes are relatively inexpensive devices ($50,000 to $60,000). They can be widely used in cranial neurosurgery procedures in which a surgeon needs to asses brain shift or lesion boundaries. These include various forms of brain cancer (astrocytoma, glioblastoma multiforme, mixed glioma, oligodendroglioma, large flaps/deep resections), as well as significant changes in blood and cerebral spine fluids, edema (swelling), tissue removal, and hemorrhages.

There have been a number of clinical trials of ultrasound-linked navigation systems for brain tumour surgery that have reported noticeably improved accuracy rates in tumour removal. One study concluded that navigation using 3D ultrasound is a “versatile, useful and reliable intraoperative imaging tool in resection of brain tumours, especially in resource-constrained settings where intraoperative MRI is not available”. (Source: Acta Neurochirurgica (Wien) 2013 Dec.)

While ultrasound-linked navigation is in fact a familiar concept to many in the field, adoption has been slow in Canada, largely because of technology compatibility issues with existing navigation solutions. The majority of hospitals have not adopted this technology for that very reason.

With Health Canada’s recent licensing of the Stealth® Navigated Ultrasound system (fully compatible with the widely used StealthStation® S7® or i7™ system, which have been used in Canada for over a decade), this is no longer a barrier to adoption. The Stealth® Navigation Ultrasound system has been approved for use in the U.S. since October 2012.

Not only is this an affordable option, deployment can usually be completed within two hours. Experience to date outside of Canada shows that surgeons are proficient  in using the technology after five to 10 training cases.

With Canadian access to affordable, easy-to-deploy solutions, ultrasound-linked navigation is poised to play a significant role in improving brain tumour removal outcomes moving forward