Nuclear Medicine Imaging of Vascular Prosthesis

Vascular graft infection is a severe, late and most unwelcome complication following vascular surgery. It has a low frequency (between 0.4% and 3.0%) [1, 2], but it is one of the most challenging issues for both diagnosis and treatment, and has high morbidity and mortality rates (around 50% and 25–75%, respectively). Its severity depends also on the location of the graft, with 13% of infections in the inguinal region followed by aortobifemoral bypass and femoropopliteal bypass. Management of infected vascular grafts depends on several factors, including the position of the infected prosthesis, the extent of infection, and the underlying microorganism [3]. Diagnosis is difficult, as there is no single diagnostic procedure that has 100% accuracy; therefore, a combination of physical examination, laboratory tests, and several imaging techniques is mandatory. Patients with suspected graft infection usually present with local pain, redness, a palpable lump, and/or secretion in the area of the surgical wound, associated with altered blood chemistry values. Microbiological cultures (obtained by a CT-guided needle aspiration, if technically feasible) may confirm the diagnosis. However, diagnosis is often difficult on clinical ground alone, because patients may have a variety of clinically equivocal complaints and assessment of the extent of graft infection (one of the most difficult challenges) is not easy. Furthermore, blood chemistry parameters can only show moderately elevated WBC counts, ESR and/or CRP values, a common, non-specific finding. When clinical signs are minimal or absent because of low-grade infection, the diagnosis of vascular graft infection is uncertain; nevertheless, it is critically important to avoid complications such as sepsis, aneurysmatic ruptures, gastrointestinal bleeding and suture line disruption. Since risk factors for infection include dissection and graft revision to remove infected material by an aggressive surgical treatment, once a vascular graft infection is suspected, early and accurate diagnosis is required for the correct choice of therapeutic procedures. Delay in treatment can lead to sepsis and/or bleeding.