Incidental findings on FDG-PET/CT in large vessel vasculitis

This study aims to determine the number and type of incidental findings detected on positron emission tomography (PET)/CT in a cohort of patients with large vessel vasculitis (LVV). Reports from PET/CT studies along with the medical charts of a cohort of patients with LVV from a Rheumatology clinic in Edmonton, Alberta, Canada, were retrospectively reviewed. Incidental findings from PET/CT, along with follow-up studies and their diagnosis were documented. The data was analyzed with descriptive statistics. The disease activity of 40 patients, with an average age of 65.8 years, was investigated using PET/CT. A statistically significant increase in incidental findings with age was observed. A total of 61 incidental findings were found in 26 (65%) patients. Of these findings, 25 were in the abdomen and pelvis. The most common incidental finding was lymphadenopathy. Follow-up investigations of incidental findings lead to 5 clinically significant findings including metastatic adenocarcinoma, Mycobacterium avium infection, papillary thyroid carcinoma, pheochromocytoma, and stroke. PET/CT is a reliable tool for determining disease activity in LVV patients and the implications of incidental findings need to be discussed with patients by the ordering care provider. This study demonstrates that incidental findings on PET/CT scan are common and increase with age in patients with LVV. A significant number of patients required further investigation for incidental findings. Key Points • Incidental findings on PET/CT scan are common in our patient population with LVV. • Frequency of incidental findings in our patient population with LVV increased with age. • Findings from this study can be used by ordering providers to have an informed conversation with their patient about the frequency of incidental findings on PET/CT scans.