Radiation-induced liver disease as a mimic of liver metastases at serial PET/CT during neoadjuvant chemoradiation of distal esophageal cancer.

Purpose: To determine the frequency and appearance of radiation-induced liver disease on PET/CT in patients undergoing serial imaging during neoadjuvant chemoradiation of distal esophageal cancer.
Materials and Methods: In this IRB-approved, HIPAA-compliant retrospective analysis, we identified 112 patients with distal esophageal cancer treated by neoadjuvant chemoradiation who had serial PET/CT imaging available for review. Two readers reviewed all studies in consensus and recorded those cases where new foci of visually detectable increased FDG avidity appeared in the liver during therapy. The etiology of such foci was determined from corresponding findings at CT or MRI, by hepatic biopsy during surgery, by characteristic evolution on post-operative imaging, or by a combination of these methods.
Results: New foci of FDG avidity developed in the liver during neoadjuvant therapy in 10 of 112 (9%) patients, of whom nine (8%) were determined to have radiation-induced liver disease based on further imaging and/or biopsy and one of whom had developed interval metastatic disease based on biopsy. In the cases of radiation-induced liver disease, the abnormal foci were found only in the caudate and left hepatic lobes, near the primary tumor, while the patient who developed interval metastatic disease had involvement of the inferior right hepatic lobe, remote from the radiation therapy field.
Conclusion: New foci of increased FDG avidity are commonly seen in the caudate and left hepatic lobes of the liver during neoadjuvant chemoradiation of distal esophageal cancer, and these findings generally reflect radiation-induced liver disease rather than metastatic disease.