High-resolution MRI better at detecting Cushing’s microadenoma

Researchers compared three types of MRI to discern which was best at finding tumors

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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A technician stands over a person who is lying down, about to have a MRI scan.

A high-resolution MRI outperformed other types of MRI at detecting microadenomas — small benign (noncancerous) tumors that form in the brain’s pituitary gland and can cause Cushing’s disease.

In a small study from China, about four in five people with Cushing’s received a correct diagnosis of a microadenoma with this type of MRI after being first misdiagnosed using a conventional or dynamic MRI.

The study, “High-resolution contrast-enhanced MRI with three-dimensional fast spin echo improved the diagnostic performance for identifying pituitary microadenomas in Cushing’s syndrome,” was published in European Radiology.

Cushing’s syndrome occurs when there’s too much cortisol in the body. Sometimes, this happens because tumors in the pituitary gland produce and release large amounts of adrenocorticotropic hormone (ACTH), which prods the adrenal glands to stimulate cortisol production. This is called Cushing’s disease.

These tumors can be very small and are sometimes difficult to detect on MRI scans.

“The identification of pituitary microadenomas is considerably challenging but critical in patients with ACTH-dependent Cushing’s syndrome,” the researchers wrote.

To understand which type of MRI can best detect a microadenoma, researchers in China compared three — conventional contrast-enhanced MRI, dynamic contrast-enhanced MRI with 2D fast spin echo, and high-resolution contrast-enhanced MRI with 3D fast spin echo.

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Results of hi-res MRI at detecting pituitary adenomas

A high-resolution contrast-enhanced MRI with 3D fast spin echo is expected to image relatively large volumes of tissue more rapidly, with higher resolution and fewer imaging-related irregularities.

Researchers looked back at the medical records of 69 patients (38 women, 31 men; median age, 39) who had an MRI between 2016 and 2020 before surgery to remove an ACTH-producing tumor.

Sixty (87%) patients had Cushing’s disease and their tumors had a median diameter of 5 millimeters. The source of excess ACTH was other than the pituitary gland in the remaining nine (13%) patients.

To see if the imaging scans were accurate, the researchers used all available information, such as other imaging tests, medical history, surgery results, and pathology reports. Two neuroradiologists looked at the scans separately to assess how well each type of MRI could detect a microadenoma.

High-resolution MRI was more accurate than a conventional or dynamic MRI. Its sensitivity was 90%-93%, meaning it correctly detected a microadenoma in most cases. Its specificity was 100%, meaning the presence of a microadenoma was ruled out in all the negative cases.

Of those who were misdiagnosed based on findings from conventional or dynamic MRI, 78% to 82% were correctly diagnosed based on the high-resolution MRI’s findings. The overall image quality was also superior with high-resolution MRI compared with the other two MRIs.

Researchers also looked at how often the neuroradiologists’ diagnoses agreed. They found the agreement between them was moderate for conventional and dynamic MRI, but almost perfect for high-resolution MRI.

“The inter-observer agreement for identifying pituitary microadenomas was almost perfect on [high-resolution MRI],” the researchers wrote, noting their study was limited by its retrospective nature and relatively small sample size. They said future prospective studies with a larger number of patients and that employ “different sequence acquisition orders” are required to confirm a high-resolution MRI’s diagnostic performance and to see if it can replace other types of imaging methods for routinely assessing the pituitary gland.