Imaging Modalities for the Diagnosis of Vascular Graft Infections: A Consensus Paper amongst Different Specialists

Abstract

Vascular graft infection (VGI) is a rare but severe complication of vascular surgery that is associated with a bad prognosis and high mortality rate. An accurate and prompt identification of the infection and its extent is crucial for the correct management of the patient. However, standardized diagnostic algorithms and a univocal consensus on the best strategy to reach a diagnosis still do not exist. This review aims to summarize different radiological and Nuclear Medicine (NM) modalities commonly adopted for the imaging of VGI. Moreover, we attempt to provide evidence-based answers to several practical questions raised by clinicians and surgeons when they approach imaging in order to plan the most appropriate radiological or NM examination for their patients.

Keywords: FDG-PET/CT; WBC scintigraphy; angio-CT; infection; multimodality imaging; personalized medicine; vascular graft.

Figure 1

(A,B) Pre-operative computed tomography (CT) scan showing graft disruption, perigraft fluid and air in a 72-year-old man with an infected abdominal endograft; (C) explanted graft after in situ repair (ISR) with visceral debranching: aorto-mesenteric bypass, right renal artery Y graft, aorto-left renal artery bypass. The reconstruction has been completed with lower extremity revascularization with extra-anatomic reconstruction (EAR) axillo-bifemoral; (D) final result after EAR.

Figure 2

Post-surgical ascending aortic repair (Bentall procedure) 1-month CT scan. From left panel to right: unenhanced CT, arterial phase and late phase CT images show aortic graft patency with perigraft fluid and stranding. These findings can be considered a typical post-operative appearance as confirmed by their disappearance in the 3-month unenhanced CT image (right image).

Figure 3

Open surgical repair of abdominal aortic aneurysm (65-year-old male). From left panel to right: unenhanced and enhanced (arterial phase and late phase) CT scans 4 months after treatment show aortic graft patency with perigraft fluid and air, enhancing the soft tissue around the graft and abscess near the right psoas muscle. These findings are consistent with perigraft infection, as also confirmed by fluid aspiration.

Figure 4

In patients with aortic stent grafts who underwent embolization for type II endoleak, diagnostic pitfalls need to be considered and known. They could be represented by hyperdense structures/materials, represented by glue/liquid embolics or coils (A–C), or also by intra-sac gas, in the case of percutaneous puncture/embolization, or new endografts with polymer-filled endobags (D–E).

Figure 5

An example of ^99mTc-labeled white blood cell (WBC) scintigraphy acquired with times corrected for isotope decay at 30 min, 2 and 20 h p.i. in a patient with suspected abdominal vascular graft infection (VGI). Planar anterior images show an increased uptake in abdominal region that was consistent for an infection (upper panel). Dingle-photon emission computed tomography (SPECT)/CT images (bottom) acquired 2 h p.i. allowed the correct localization of the uptake in the inner of abdominal aortic graft.

Figure 6

An example of negative [¹⁸F]FDG PET/CT scan in a patient with suspected infection of abdominal graft implanted 2 years before for the exclusion of a large aneurysm. The images show mild (SUVmax 2.4), homogeneous uptake along the whole tract of the prosthesis without any focal uptake.