Usefulness of 18F FDG PET/CT in evaluating disease activity at different times in a patient with chronic periaortitis

We report the case of a 53 year old man with a chronic periaortitis (CP) in whom Fluorine 18 Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) has been useful in assessing the disease extent at diagnosis, in evaluating the treatment response, in diagnosing the relapse, and in monitoring the disease activity during follow up. This case highlights the usefulness of FDG PET/CT at different times in patients with CP. CP is a rare inflammatory disorder that affects the abdominal aorta and the retroperitoneum. Imaging procedures are essential to diagnose and monitor the disease course. Ultrasonography may be used as first line screening test, and is particularly useful to monitor patients with hydronephrosis and aortic aneurysms. However, CT or magnetic resonance imaging (MRI) of the abdomen are currently considered the investigations of choice to diagnose CP. In active CP, the periaortic mass usually enhances on CT and MRI. Both these methods can be used to monitor the disease course of CP and to evaluate response to treatment. A note of caution: signs of vasculitis seen on MRI and CT may persist for some time, despite achievement of clinical remission. A further limitation of abdominal CT and MRI is that neither technique can detect vasculitis in vessels other than the abdominal aorta, which has been described in 43% of patients with CP. FDG PET/CT has been proposed as useful tool in inflammatory diseases, such as aortitis, because metabolic changes assessed by FDG PET/CT usually precede morphological changes assessed by conventional imaging methods. Our case highlights the usefulness of FDG PET/CT at different times in patients with CP. This method may be useful in assessing disease activity and extent at diagnosis, in evaluating the treatment response, in diagnosing the relapse, and in monitoring the disease during follow up