Neurology and Neurosurgery

March 26, 2024

Mayo Clinic is using new imaging techniques to detect corticotroph adenomas not well seen with conventional MRI. The goal is to enhance the management of Cushing disease. Initial outcomes are promising, including results obtained from photon-counting detector CT.

"In our first few months using this modality, we imaged eight patients and found an adenoma in all of them — confirmed at surgery," says Ian T. Mark, MD., MSM, a neuroradiologist at Mayo Clinic in Rochester, Minnesota. The work is a collaborative effort involving Radiology, Neurosurgery and Endocrinology.

Cutting-edge imaging improves tumor resection. "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," says Jamie J. Van Gompel, M.D., a neurosurgeon at Mayo Clinic's campus in Minnesota.

Other new imaging options for corticotroph adenomas include:

• Multiple contrast-enhanced MRI sequences, including double inversion recovery, submillimeter 3D dynamic pulse Cartesian acquisition with projection reconstruction-like (pCAPR) sampling, and fast imaging employing steady-state acquisition-constructive interference in steady state (FIESTA-CISS).
• 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 pituitary adenomas 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."

Unique use of photon-counting detector CT

About half of corticotroph adenomas aren't clearly visible on standard MRI, which is limited by skull base artifacts and low spatial resolution.

Photon-counting detector CT, which directly counts each X-ray photon to characterize its energy, yields submillimeter imaging slices. With iodine maps, the technology also can increase the conspicuity of hypoenhancing adenomas relative to the pituitary gland.

"Compared with conventional CT, photon-counting detector CT gives us thinner slices and brighter contrast," Dr. Mark says. Temporal resolution also is enhanced, allowing for faster scanning time.

Mayo Clinic installed the world's first photon-counting scanner in 2014. Mayo's CT Clinical Innovation Center works to help develop clinical applications for photon-counting CT technology. As a result, Mayo Clinic is unique in using photon-counting detector CT to identify corticotroph adenomas.

MRI innovations

Mayo Clinic has a distinguished history of imaging innovations. Physicists and clinicians collaborate to spread those innovations across medical specialties. "We have the ability to push new technology into directly helping patients faster than other centers can," Dr. Mark says.

The unique pCAPR MRI sequence for imaging the pituitary is based on a sequence developed 15 years ago at Mayo Clinic for imaging the prostate gland. "We've now been able to bring that sequence into use for the pituitary," Dr. Mark says. "Traditional dynamic MRI imaging of the pituitary results in 2D slices that are relatively thick — about 2 to 3 mm. But our new technique gives us 3D submillimeter slices."

Mayo Clinic is committed to pioneering new technology that improves Cushing disease care. "We use advanced imaging that a lot of other centers don't have," Dr. Van Gompel says. "The ultimate goal is to cure patients."

For more information

CT Clinical Innovation Center. Mayo Clinic.

Refer a patient to Mayo Clinic.