# Fusion Imaging of 18F-FDG PET and MRI Identified an Inflammatory Esophageal Diverticulum in a Patient with Radioiodine-Refractory Differentiated Thyroid Cancer

## TL;DR

Combining PET and MRI imaging helped diagnose an inflammatory esophageal diverticulum in a thyroid cancer patient.

## Contribution

Demonstrates the diagnostic benefit of PET/MRI fusion imaging in ambiguous cancer cases.

## Key findings

- PET/CT showed a hypermetabolic esophageal region but was inconclusive.
- PET/MRI fusion identified an air-containing inflammatory diverticulum.
- Diagnosis was confirmed via endoscopy without additional tests.

## Abstract

A radioiodine-refractory differentiated thyroid cancer patient with rising serum thyroglobulin (Tg) levels underwent 18F-FDG PET/CT scan, which showed a hypermetabolic region in the proximal segment of esophagus, leading to ambiguity in diagnosis. MRI was immediately added, and PET/MRI fusion image localized an air-containing lesion interlinked with esophagus with enhanced T2 hyperintense mucosal signal, indicating an inflammatory esophageal diverticulum, which was subsequently verified by endoscopy. This case highlights the added value of PET/MRI image fusion in cases with inconclusive 18F-FDG PET/CT findings, requiring no additional tests and utilizing existing software, thereby minimizing the need for invasive procedures.