New Imaging Techniques Found to Improve Detection of Cushing’s

But no alterations seen in reported remission, recurrence rates: study

Patricia Valerio, PhD avatar

by Patricia Valerio, PhD |

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A technician readies a patient to have an MRI scan.

Despite advancements in imaging techniques that have improved the detection of Cushing’s disease over the last four decades, no alterations in reported remission and recurrence rates were found for the rare disorder in a new review study.

In studies published to date, however, there might be an association between one MRI technique, called gradient recalled echo (GRE), and these clinical outcomes, according to researchers.

But there is insufficient “high-quality evidence in the published literature reporting on the effects of imaging on clinical outcomes,” the team wrote.

“This, along with substantial heterogeneity, makes it difficult to draw firm conclusions from our results,” they wrote, adding that “advances in imaging alone may be insufficient to improve surgical outcomes.”

The review study, “The clinical outcomes of imaging modalities for surgical management Cushing’s disease – A systematic review and meta-analysis,” was published in the journal Frontiers in Endocrinology.

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Cushing’s disease is marked by the excessive production of adrenocorticotropic hormone (ACTH), which in turn increases cortisol production. ACTH overproduction is typically driven by benign tumors, called adenomas, in the pituitary gland — a pea-sized gland located at the base of the brain.

In most cases, patients have small ACTH-producing pituitary tumors, called microadenomas, that measure less than 10 millimeters (mm) in diameter on average. In rarer cases, large tumors called macroadenomas, measuring more than 10 mm in diameter, have been found in patients.

Diagnosing Cushing’s disease can be challenging and require a combination of different medical approaches. Imaging techniques, including MRI, have been used to improve its detection rate.

“However, [their] impact … on clinical outcomes is unclear,” the researchers wrote.

Now, a research team in the U.K. sought to evaluate whether advances in imaging techniques in recent years have contributed to improve Cushing’s disease clinical outcomes, such as remission and recurrence rates.

To do so, the team conducted a review of published studies — and focused on 166 that were eligible to be used in their analyses.

These studies involved 13,181 patients and were conducted over the course of 44 years. From these, 160 involving 12,994 patients reported remission rates after a single tumor removal surgery. The overall remission rate was 77%.

Statistical analyses revealed that undetectable lesions, previous surgery, lesions measuring 10 mm or more (macroadenomas), or tumor invasion into nearby tissues all were factors associated with lower chances of remission.

In addition, the MRI technique GRE was identified as a significant predictor of higher remission rates compared with standard MRI scans performed before surgery. GRE is a technique that’s particularly useful when rapid imaging is required.

A total of 106 studies involving 7,185 patients reported disease recurrence rates. The pooled recurrence rate was 14.5%.

A macroadenoma was found to be associated with higher reported recurrence rates, as was a greater follow-up duration.

Further, studies employing GRE reported significantly lower disease recurrence rates compared with those using standard MRI before surgery.

Additional analyses demonstrated that even given the improvements in Cushing’s disease detection rates over the past four decades, there were no significant improvements in either disease remission or recurrence rates.

“This is, to our knowledge, the largest [analysis] addressing the investigation and surgical management of Cushing’s disease,” the researchers wrote.

The team noted, however, that their study was limited by the poor quality of evidence on the topic and the risk of bias, adding that their findings should be interpreted with caution.

Hence, “there is a need for high-quality, prospective, comparative studies with a standardised framework for evaluation and reporting,” they concluded.