The Utility of Magnetic Resonance Imaging for Hypophysitis Secondary to Immune Checkpoint Inhibitor Use

Immune checkpoint inhibitor (ICI) therapy is an efficacious cancer treatment, often resulting in autoimmune off-target effects. Magnetic resonance imaging (MRI) has been a recommended investigation for ICI-related hypophysitis. We sought to identify the frequency of identifiable MRI changes.

A retrospective case-control audit was performed of individuals who received one or more ICI between January 2018 and December 2023 at a single tertiary referral centre in Melbourne, Australia.

Individuals requiring hormone supplementation were screened for hypophysitis. A randomly selected control group receiving ICI demonstrated normal pituitary function at the time of MRI.

Fifty-four (6.9%) of 778 individuals who received ICI therapy were diagnosed with ICI-related hypophysitis. 43 had an MRI examining the pituitary gland within 2 months. Four (9.3%) had initial reporting consistent with hypophysitis. Upon re-examination by an MRI-Fellowship trained radiologist, a further 6 (total 10, 23%) had acute hypophysitis changes. Among the control group, 45 of 46 individuals had an MRI within 2 months of normal pituitary biochemistry. All initial MRI reports were normal, but upon review 1 (2.2%) had acute hypophysitis abnormalities, with a significant difference between groups (10/43 vs 1/45, p = 0.003). Within the control group, a further 10 (22%) individuals had an atrophic pituitary and/or empty sella. No other significant pituitary pathology, including pituitary metastasis, was identified.

Although changes were observed in a minority of patients with hypophysitis, MRI provides minimal additional clinically meaningful information, so it could be reserved for atypical cases or those with persisting symptoms despite adequate supplementation.