Date of Award

January 2021

Document Type


Degree Name

Medical Doctor (MD)



First Advisor

Darko Pucar


As the use of immunotherapy continues to expand in the field of cancer treatment, adverse effects including immune checkpoint inhibitor (ICI)-induced thyroiditis are commonly seen. The purpose of this study was to examine the role of 18F-FDG-PET/CT imaging in the detection of ICI-induced thyroiditis. Fourteen patients treated with ICI therapy for metastatic cancer between September 2016 and November 2019 were identified through a retrospective chart review and confirmed to have thyroid dysfunction on PET/CT scans and laboratory analysis. Eight patients treated with ICI therapy who had PET/CT imaging and no thyroiditis were selected to be the control group. SUVmax and SUVmean of the thyroid and liver on baseline and post-therapy scans were evaluated. Thyroid SUVmax and SUVmean values on post-therapy scans among patients with thyroiditis were found to be significantly higher compared to patients without thyroiditis (mean SUVmax = 5.30, 2.02, respectively; P = .002; mean SUVmean = 4.47, 1.60; P = .001). Objective threshold values of thyroid SUVmax > 2.9, thyroid SUVmean > 2.4, and thyroid SUVmax/liver SUVmean > 1.25 could perfectly distinguish the thyroiditis patient group from the control group. Other effective methods of identification were thyroid SUVmax > liver SUVmax and a Deauville 5-Point Scale score of 4 or greater.


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