Nerve tumors shown open to exposure by diffusion tensor imaging

A neurosurgeon and a neuroradiologist have put their heads together and come up with a new way to map nerve fibers with fine precision prior to removing a particular type of nerve tumor.

The surgeon, Michel Kliot, MD, and the radiologist, Thomas Gallagher, MD, both of Northwestern Medicine in Chicago, successfully used the MRI sequence known as diffusion tensor imaging (DTI) to image and remove a rare tumor of the tissue surrounding nerves, according to a Northwestern news release.

Called a schwannoma, this type of tumor presents a special imaging challenge. Traditional MRIs often fail to yield a full picture of nerve fibers, and surgeons need to navigate intricate clusters to access schwannomas.

Kliot said DTI allows the surgeon to better understand the orientation of tumors growing within nerve fibers by showing the diffusion of water molecules in and around the nerves. The technique produces bright images that can be displayed in either 2D or 3D.

“By having a more precise pre-operative diagnosis, we are armed with a better surgical plan that will give us the most direct yet least invasive path for removing nerve tumors,” said Kliot. “For patients, this means smaller incisions and a reduced risk of damaging functioning nerve fibers.”

Northwestern noted that DTI is new for this particular application, but a notable success with a recent case is encouraging. Most schwannomas are benign and slow to grow, but one they recently resected was progressing and causing the patient pain. The patient underwent DTI-guided surgery and returned to work about a week later.

Gallagher, who subspecializes in functional neuroradiology, said DTI might “extend beyond nerve tumors, and give us insight into many different nerve pathologies, traumatic nerve injuries and even the regrowth or recovery of nerves over time.”

Northwestern has posted the release, along with a color image.