Neuronavigational Treatment Options for Brain Tumors; PoleStar® Introperative MRI (iMRI)
Neurosurgeons have the ability to bring images of the patient's brain into the operating room to guide surgical approaches. Any digital scan — CT, MRI or PET — can be loaded onto a workstation in the operating room. When needed, multiple image sets can be fused, using a process known as registration. Using specially placed skin markers or the patient's own anatomy, the image information is matched to the patient. This allows the surgeon to touch any point in the surgical field and see that point displayed on the workstation screen. With this information, the exact contours of a tumor can be mapped before surgery.
Compared to older techniques based on scalp landmarks, this method of surgical navigation greatly improves the accuracy of cranial approaches, allowing for smaller incisions and putting less "eloquent brain" at risk. The "eloquent brain" refers to the parts of the brain that allow you to interact with and process the world via your senses, motion, language, memory and the purposeful use of tools.
While the use of surgical navigation has been an important advance in brain tumor surgery, its utility is limited by the phenomenon known as brain shift. Whenever the brain is exposed, cerebral spinal fluid (CSF) is lost. Additionally, when tumor resection is begun, the position of the surgical field can shift by centimeters, compared to the presurgery position. Brain shift makes it potentially hazardous to rely on preoperative images to determine the location of residual tumor. The only way to deal with brain shift and maintain accurate neuronavigation is with intraoperative imaging. For brain tumor surgery, this is best done with intraoperative MRI (iMRI).
This very small and compact system is used specifically for intracranial surgery. With a compact design and low field strength, it can be conveniently docked under an operating table to enable the full range of surgical instruments to be used. Images are acquired by raising the magnet to scanning position. When brain shift occurs during surgery, a new image can be obtained and surgical navigation can be done with the updated information.