Aortic Prosthetic Graft Infections: Radiologic Manifestations and Implications for Management

Abstract

Prosthetic graft infections are an uncommon complication of aortic bypass. These infections may have serious sequelae such as limb loss and can be lethal. They are hard to eradicate and, under certain circumstances, difficult to diagnose. Usually, computed tomography (CT) is the most efficacious imaging method for diagnosis of graft infections due to its quick availability. The sensitivity of magnetic resonance imaging in detection of perigraft infection has not been thoroughly investigated but is probably similar to that of CT. After the early postoperative period, persistent or expanding perigraft soft tissue, fluid, and gas are the CT findings of graft infection. Aortoenteric fistula should be considered a subset of aortic graft infection; however, perigraft air is more likely to be seen with an aortoenteric fistula. Other conditions associated with graft infection include pseudoaneurysm, hydronephrosis, and osteomyelitis. Adjunctive studies such as sinography, ultrasonography, gallium scanning, and labeled white blood cell scanning can be quite useful in diagnosis, determination of the extent of disease, and selection of the treatment modality. White blood cell scanning is an important complementary test to CT in ambiguous cases, such as in the early postoperative period, and may be more sensitive in detection of early graft infection.

Diagnosis of Aortic Graft Infection: A Case Definition by the Management of Aortic Graft Infection Collaboration (MAGIC)

“…5 Notwithstanding significant deficiencies in the published evidence and in order to define a necessary time point "cutoff", the recommendation that AGI should be strongly suspected if CT demonstrates perigraft fluid at 3 months post-graft insertion was considered reasonable and consistent with clinical experience. 18 This criterion is not 100% specific as fluid has very exceptionally been reported at 1 year without AGI, 19 but such limitations highlight the importance of no single feature being diagnostic and the requirement for corroborative evidence from other categories to fulfill the definition. Although not universally available, research is currently underway to determine the utility of 18 F-FDG-PET/CT, which has significant potential in improving diagnosis of AGI and monitoring response to treatment.…”

“…21e23 Secondary involvement by contiguous spread of infection involving adjacent structures may also, for example, cause hydronephrosis, focal bowel wall thickening, psoas abscess, and vertebral osteomyelitis/discitis but require the presence of major features to conclude AGI definitively. 18,22 Although a well-recognized feature of AGI, pseudoaneurysms may also occur for noninfective reasons such as dehiscence of a suture line. Finally, AGI is unlikely to be confused with primary large vessel vasculitis, which is rare in comparison, not typically localized to the region around a stent-graft, and associated with uniform mural thickening that is not characteristic of infection.…”

“…24 With regard to the utility of other imaging techniques, magnetic resonance imaging has not been evaluated as extensively as CT but may be more sensitive in detection of inflammatory changes (e.g., in the psoas muscle) and can distinguish hematoma from perigraft fluid. 18,25 The sensitivity of technetium-99m/indium-111-labeled leukocyte imaging has been suggested to approach 100%, but false positivity is an issue and CT (or single-photon emission CT/ CT if available) is usually required to delineate the significance of abnormal uptake consistent with focal infection/ inflammation. 18,25,26 18 F-fluorodeoxyglucose positron emission tomography (PET)/CT shows promise, but careful interpretation is required as prosthetic grafts can also provoke chronic low-grade inflammation for several years after surgery with associated diffuse tracer uptake.…”

Nonvalvular Cardiovascular Device–Related Infections

“…In contrast, infection of intracavitary graft locations may present with nonspecific findings and be more difficult to diagnose. 111 This difficulty is only magnified when infection presentation occurs years after graft placement. Gastrointestinal bleeding due to aortoenteric fistula formation or erosion is seen in a minority of patients with aortic graft infection, and its occurrence dictates an evaluation for graft infection.…”

The choice of vascular prosthesis in high-risk aortic surgery

“…Для локализации зоны инфицирования использо-вали методы лучевой диагностики [3,12], в частности, ультразвуковое исследование (УЗИ) и мультиспиральную компьютерную томографию (МСКТ), которые дают воз-можность визуализировать парапротезную гематому и ее эволюцию, выявить характерные для инфицирования признаки (увеличение объема, изменение плотности ге-матомы), накопление перипротезного воспалительного экссудата. Кроме того, визуализирующие методы позво-ляют диагностировать развитие наиболее грозного ослож-нения течения инфекционного процесса -нарушение герметичности анастомоза с формированием ложной аневризмы и аррозивного кровотечения.…”