University HealthCare Alliance

December 30, 2019

Stanford Medicine | A New View on Brain Surgery

Guided by lasers, fluorescence and real-time imaging, surgeons develop new ways to enhance precision

Gordon Li stared down at a mass of pinkish-gray tissue. He turned to the neurologist beside him and, from behind his surgical mask, cued the next step of the procedure. “Really step it up for this part. Test her hard,” he said.

Li, MD, associate professor of neurosurgery, was in the midst of an open-brain surgery and the “her” was Lisa Inouye, who lay awake on the operating table. Li was removing a tumor in a region of Inouye’s brain that controls movement, and her lucid state allowed Li to ask Inouye to perform certain tasks, ensuring that he was not cutting out parts of her brain critical for those actions.

As instructed, the neurologist began rattling off a list of physical to-dos — touch your nose, tap your fingers, kick your leg out. Inouye touched, tapped and kicked as Li cut out bits of tumor.

“It was textbook,” Li recalled.

That is, until he saw what appeared to be more tumor tissue — this part of the mass hadn’t shown up on a pre-operative brain scan. After a bit of visual inspection and prodding — brain tumors feel mushier than healthy brain tissue — Li surmised the tissue was very likely part of the tumor and needed to be taken out. But before making the cut, he conducted one more review, this time using a new, experimental tool. Li had been collaborating with Eben Rosenthal, MD, a surgeon-scientist who is developing a targeted fluorescent dye that clings to and illuminates cancer. The idea behind this new dye — Inouye was the seventh Stanford patient to consent to its use during brain surgery — is to help surgeons spot cancer in real time, as they operate.

He aimed a special camera at the possibly cancerous tissue, and from the screen emanated a glow of confirmation.

By the end of the surgery, Li had removed 98% of Inouye’s tumor — a good bump from the 90% he had anticipated. Although it’s still early in the dye’s development, Li sees potential for its use in future operations. “It’s clear how this dye could act as a guide for surgeons in murky territory,” he said. “Determining where and what to cut is not always so obvious.”

In fact, more often than not brain surgery requires a bit of guesswork. In search of more reliable guides than inexact visual and tactile cues, brain surgeons have turned to technology. Some, like Rosenthal, are developing newer imaging methods that they hope will let surgeons augment what they see with the naked eye. And some are turning to MRI — normally a diagnostic tool — to steer the course of their procedures.

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