The tiny tumors that cause Cushing disease are tough to detect with standard MRI. Fortunately, some new options are available, boosting the chances for successful treatment.
“Sometimes pituitary tumors are so small, they’re nearly impossible to see,” says Mayo Clinic neurosurgeon Dr. Jamie J. Van Gompel. “The success of surgery drops dramatically when we can’t see these tumors on imaging. Anything that tells us where the tumor is will help us determine the risks of surgery and also improve the chances of long-term cure.”
About half the tumors that cause Cushing disease aren’t clearly visible on standard MRI. Standard MRI provides 2D images of relatively large sections of the pituitary, which might not show a tumor that’s only several millimeters in size. Pituitary MRI is also prone to visual flaws or artifacts.
“It’s hard for MRI to image tissue that’s near air. And the pituitary always has air next to it, from the sinuses,” explains Mayo Clinic neuroradiologist Dr. Ian T. Mark.
To overcome these challenges, Mayo Clinic uses several new technologies:
- An MRI sequence — developed at Mayo Clinic and only available there — that yields 3D images of submillimeter sections of the pituitary.
- A technology known as photon-counting detector CT, also developed at Mayo and only available there. CT avoids problems with artifacts while imaging submillimeter pituitary sections. “In our first few months using this modality, we imaged eight patients and found an adenoma in all of them — confirmed at surgery,” Dr. Mark says.
- 7T MRI, which uses a stronger magnet to provide better contrast and detail. Mayo Clinic was the first center in North America to use clinical 7T MRI.
- Intraoperative ultrasound, which during surgery can confirm the presence of a tumor previously seen on MRI.
Finding and removing a pituitary adenoma helps patients avoid additional treatment and risks. “If we don’t cure a patient with pituitary surgery, there’s a high risk of needing surgery to remove the adrenal glands,” Dr. Van Gompel says. “If we treat the Cushing disease by removing the adrenal glands, then sometimes the pituitary tumor grows. It can grow really fast and become problematic, even though we couldn’t see it before.”
Mayo Clinic is committed to pioneering new technology that improves Cushing disease care. As Dr. Van Gompel explains, “We use advanced imaging that a lot of other centers don’t have. The ultimate goal is to cure patients.”
