Chronic vascular graft infection with fistula to bone causing vertebral osteomyelitis, imaged with F-18 FDG PET/CT.

Vascular grafts have an infection rate ranging from 1% to 3%. While early infections occur within 4 months after surgery and are associated with virulent organisms, late infections can occur after months to years of surgery and are often caused by low virulence organisms that survive in an adherent biofilm. Host defense recognition of bacterial biofilm can result in perigraft abscesses, aorto-enteric fistulas, and very rarely, fistulas into adjacent bone. We present a case of an 83-year-old man, who had an F-18 FDG PET/CT scan for workup of a solitary pulmonary nodule, and was incidentally diagnosed with chronic multifocal infection of an aorto-iliac vascular graft, with an infected fistula tract into adjacent bone causing chronic vertebral osteomyelitis, which was confirmed with a contrast-enhanced CT. The patient was asymptomatic and not a surgical candidate, and was treated conservatively with a course of antibiotics. This case highlights the utility of F-18 FDG PET/CT in the imaging of chronically infected vascular grafts and in identifying potentially lethal complications such as fistulas into adjacent structures.