The Brain Tumor ProgramBrain Tumor TreatmentsIntra-operative MRI (Polestar) Printer Friendly Page

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A compact OR-based MRI system at the University of Medicine and Dentistry of New Jersey-University Hospital is providing neurosurgeons with unparalleled advantages in real-time visualization of the brain during surgery. The new system allows surgeons to confirm the location of lesions, plan and reconfirm the optimal surgical approach, and verify complete lesion removal prior to closure without disrupting normal surgical procedures.

"Intraoperative MRI has been the Holy Grail of neurosurgery for the last decade," says Michael Schulder, MD, Associate Professor of Neurological Surgery at UMDNJ's New Jersey Medical School. "Neurosurgery involves striking a balance between the desirability of removing a tumor or lesion and the avoidance of complications or injury to the brain. It's all about getting the most precise image possible upon which to plan your surgical approach. MRI images obtained during surgery give us the best data to maximize recovery and minimize harm."

While today's computer-assisted surgical navigation systems have increased the precision by which the brain's anatomy and the location of the lesion are identified, they suffer from a significant drawback: their reliance on CT or MRI scans obtained before surgery.

"Changes that occur during surgery are not and cannot be reflected in these navigation systems," cautions Peter Carmel, MD, Professor and Chair of the Department of Neurological Surgery at NJMS. "The brain may shift position simply from exposure or from tumor removal, causing reliance on preoperative images to be potentially dangerous. That's why MRI images obtained while the patient is on the OR table are so crucial – we can correct our approach right then and there and avoid harming healthy tissue."

Early versions of OR-based MRI systems were fraught with problems. A special shielded OR had to be constructed, often on the basement level and separate from the main OR suite. Entire new sets of instruments and equipment were needed as ferromagnetic materials could not be kept in the same room as the MRI magnet, thus preventing the use of the room for other non-MRI cases. Surgical access was limited by the magnet design, forcing the surgeon to work in a physically restrictive and uncomfortable environment.

The PoleStar N-20 system is the first intraoperative MRI unit designed for a conventional OR. The small, low-field-strength magnet is stored in a corner of the OR until it is needed. Then, the unit is parked under the head of the operating table where it can be raised and lowered by a hand-held remote control unit. The surgeon also controls the type and number of images to be taken through the same remote control unit. The low magnetic field permits the use of conventional OR tables, lights, etc.; only those tools used directly in the surgical field must be MRI-compatible. The design of the unit allows surgeons and nurses to carry out normal tasks from the same position as in conventional surgeries.

The PoleStar N-20 system is manufactured by Odin Technologies, an Israeli imaging equipment manufacturer. It was developed and is currently utilized on a regular basis at Chaim Sheba Medical Center in Tel Hashomer, Israel. University Hospital was the second facility in the world to have and use the system.

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