Aortic prosthetic graft infections: radiologic manifestations and implications for management

Outcomes of native or graft abdominal aortic infection managed with orthotopic xeno pericardial grafts or cryopreserved allograft: A French bicentric comparative study

BACKGROUND

The ideal substitute for in situ reconstruction of aortic graft or native aortic infection has yet to be defined. Though recognized as resistant to infection, cryopreserved arterial allograft (Allograft) presents problems of availability when treating emergent cases, with the risk of long-term aneurysmal degeneration. Commercially available bovine pericardial substitutes (Pericard) seems to be an alternative, with promising results in the recent literature. The goal of this study was to compare the results of these two substitutes.

METHODS

Between January 2010 and December 2023, we conducted a retrospective observational study in two tertiary centers, including all patients having undergone in situ surgery for aortic graft or native aortic infections with reconstruction by Allograft or Pericard. Survival, reinterventions and reinfections were analyzed according to the Kaplan-Meier method and Cox regression model.

RESULTS

All in all, 169 patients were included in the study with 103 aortic graft infections (60.9%), 33 aortic endograft infections (19.5%), and 33 native aortic infections (19.5%). Allograft was used in 111 patients (65.7%) and Pericard in 58 (34.3%). The two groups were comparable as regards preoperative risk factors, types of index surgery, and infectious agents, with 41 patients (24.8%) with an aortoenteric fistula. There was no significant difference in postoperative complications. The median follow-up was 18 months (interquartile range, 4-44 months). At 24 months, survival was comparable, with 68 ± 4% for Allograft and 68 ± 6 for Pericard, as was reinfection-free survival with 80 ± 4% for Allograft vs 83 ± 6% for Pericard (P = .722). Reintervention-free survival at 2 years was likewise comparable: 86 ± 4% for Allograft vs 77 ± 8% for Pericard (P = .419).

CONCLUSIONS

A pericardial substitute offers the possibility of in situ aortic reconstruction without the problems of availability and with midterm results comparable with those achieved with aortic allografts. Further studies with long-term follow-up are needed to validate the absence of late reinfection and to confirm pericardial substitute patency.

Twenty-Five Year Multicentre Experience of Explantation of Infected Abdominal Aortic Endografts

We report a multicenter experience of open conversions (OC) for aortic endograft infections (AEI). We retrospectively analyzed all patients who underwent OC for AEI after endovascular aneurysm repair (EVAR), from 1997 to 2021 in 12 Italian centers. The endpoints were as follows: mortality (30-days, in-hospital), major postoperative complications. Follow-up data included: survival, aortic-related complications, infection persistence or reoccurrence. Fifty-eight patients (mean age: 73.8 ± 6.6 years) were included. Median time from EVAR to OC was 14 months (interquartile range 7-45). Thirty-five patients (60.3%) were symptomatic at presentation. Aortic reconstruction was anatomic in 32 patients (55.2%), extra-anatomic in 26 (44.8%). Thirty-day mortality was 31% (18/58). Six additional patients died after 30 days during the same hospitalization (in-hospital mortality: 41.4%). Most common post-operative complications included respiratory failure (38.6%) and renal insufficiency (35.1%). During 28.1 ± 4 months follow-up, 4 aneurysm-related deaths were recorded. Infection re-occurred in 29.4% of the patients. Estimated survival was 50% at 1 year, and 30% at 5 years, and was significantly lower for patients who underwent extra-anatomic reconstructions (37 vs 61% at 1 year, 16 vs 45% at 5 years; log-rank P = .021). OC for AEI is associated with high early mortality. The poor mid-term survival is influenced by aortic complications and infection re-occurrence.

Case Report: False aneurysm as a late unusual complication of the aortofemoral bypass graft in a patient with critical leg ischemic symptoms: interesting case

Aortofemoral bypass surgery is a common procedure for treating aortoiliac occlusive disease, also known as Leriche syndrome, which can cause lower extremity ischemic symptoms. Diagnostic imaging techniques play a crucial role in managing pseudoaneurysms (PSAs), with Duplex ultrasound and Computed Tomography-angiography (CTA) being effective tools for early diagnosis. Pseudoaneurysms (PSAs) present as pulsating masses with various symptoms, and prompt intervention is essential to avoid complications. A case report is presented involving an 82-year-old male who underwent aorto-bifemoral bypass surgery and later developed a pseudoaneurysm (PSA) of the left branch. Surgical treatment involved the removal of the pseudoaneurysm (PSA) and graft replacement. Other cases from the literature are also described, emphasizing the rarity and potential severity of non-anastomotic pseudoaneurysms (PSAs) in reconstructive vascular surgery. Periodic screening of patients who undergo reconstructive vascular surgery is crucial to detect pseudoaneurysms (PSAs) early and prevent complications. Asymptomatic pseudoaneurysms (PSAs) can grow significantly and become life-threatening if not identified in a timely manner. Regular post-operative imaging, such as annual Computed Tomography-angiography (CTA) and/or Duplex ultrasound, is recommended to ensure early diagnosis and appropriate management of complications.

Distinguishing sterile inflammation from graft infection

We describe the case of a 68-year-old man who underwent ascending aortic replacement and thoracic endovascular aortic repair. Four years later, the patient developed neck pain on the right side and chest computed tomography showed expansion of fluid in the mediastinum which had extended to the neck. Echocardiography revealed advanced severity of aortic regurgitation and decreased ejection fraction. Given the progression of aortic regurgitation, decreased cardiac function, and rapidly expanding fluid accumulation causing neck pain, reoperation was indicated. All microbiological test including polymerase chain reaction were negative indicating absence of any infection. The patient is being followed-up without antibiotics and CT has not shown peri-graft fluid 2 years postoperatively. Since infection cannot be excluded completely, it is important to assess the condition with selective medium, extended culture periods, genetic testing, and consultations with microbiology laboratories when normal culture tests for general bacteria, and fungi are negative which can help avoid drug-resistant bacteria count, elevated medical costs, and drug side effects due to the improper use of antibiotics through proper diagnosis.

Presentation and management of delayed aortic endograft infection

A man in his 60s who underwent endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm 4 years ago presents with 1 week of abdominal pain, fever and leucocytosis. CT angiogram demonstrated an enlarged aneurysm sac with intraluminal gas and periaortic stranding consistent with infected EVAR. He was clinically unfit for an open surgical intervention due to his significant cardiac comorbidities, including hypertension, dyslipidaemia, type 2 diabetes, recent coronary artery bypass grafting and congestive heart failure secondary to ischaemic cardiomyopathy with an ejection fraction of 30%. Therefore, due to this significant surgical risk, he was treated with percutaneous drainage for the aortic collection and lifelong antibiotics. The patient is well 8 months following presentation with no signs of ongoing endograft infection, residual aneurysm sac enlargement, endoleak or haemodynamic instability.

Diagnosis and treatment of vascular graft and endograft infections: a structured clinical approach

A vascular graft or endograft infection (VGEI) is a severe complication that can occur after vascular graft or endograft surgery and is associated with high morbidity and mortality rates. A multidisciplinary approach, consisting of a team of vascular surgeons, infectious diseases specialists, medical microbiologists, radiologists, nuclear medicine specialists, and hospital pharmacists, is needed to adequately diagnose and treat VGEI. A structured diagnostic, antibiotic, and surgical treatment algorithm helps clinical decision making and ultimately aims to improve the clinical outcome of patients with a VGEI.

Femur Osteomyelitis and Associated Fracture as an Initial Presentation of Aortoenteric Fistula

Aortoenteric fistula is a rare condition. Atypical presentations may cause significant management delays. We present the case of a 64-year-old male who experienced a pathological femoral fracture as an initial presentation of an underlying aortoenteric fistula. The aortoenteric fistula, possibly related to a poor graft tunneling technique, induced femur osteomyelitis and the associated pathological fracture.

FDG PET/CT in abdominal aortic graft infection: A case report and literature review

This case report follows a 47-year-old man who had multiple grafts undergoing FDG PET/CT (positron emission tomography/computed tomography) scan to evaluate for graft infection. Initial CT showed enhancing soft tissue and fluid collection around the graft, and the subsequent FDG PET/CT showed findings concerning for graft infection. This case exemplifies that FDG PET/CT is a synergistic tool in diagnosing aortic graft infections, a rare and often fatal complication of aortic grafts.

Imaging Challenges in Chronic Dissection

Chronic aortic dissection comprises a heterogeneous group of unrepaired and repaired disease requiring lifelong clinical and imaging surveillance. CT and MRI are the main imaging modalities for longitudinal surveillance, with growing interest in emerging imaging techniques for prognostic potential. Imaging difficulties span technical and diagnostic challenges, some of which are unique to the repaired aorta, with specific complications depending on the type of repair. This review describes existing and emerging imaging techniques, outlines the technical and diagnostic challenges encountered at CT and MRI, and highlights the diagnostic pitfalls of chronic aortic dissection.

Contrast-enhanced US Evaluation of Endoleaks after Endovascular Stent Repair of Abdominal Aortic Aneurysm

Ruptured abdominal aortic aneurysm (AAA) carries high morbidity and mortality. Elective repair of AAA with endovascular stent-grafts requires lifetime imaging surveillance for potential complications, most commonly endoleaks. Because endoleaks result in antegrade or retrograde systemic arterialized flow into the excluded aneurysm sac, patients are at risk for recurrent aneurysm sac growth with the potential to rupture. Multiphasic CT has been the main imaging modality for surveillance and symptom evaluation, but contrast-enhanced US (CEUS) offers a useful alternative that avoids radiation and iodinated contrast material. CEUS is at least equivalent to CT for detecting endoleak and may be more sensitive. The authors provide a general protocol and technical considerations needed to perform CEUS of the abdominal aorta after endovascular stent repair. When there are no complications, the stent-graft lumen has homogeneous enhancement, and no contrast material is present in the aneurysm sac outside the stented lumen. In patients with an antegrade endoleak, contrast material is seen simultaneously in the aneurysm sac and stent-graft lumen, while delayed enhancement in the sac is due to retrograde leak. Recognition of artifacts and other potential pitfalls for CEUS studies is important for examination performance and interpretation. Online supplemental material is available for this article. ^©RSNA, 2022.

Diagnostic accuracy of FDG PET for the identification of Vascular Graft Infection

BACKGROUND

Fluorodeoxyglucose (FDG) positron emission tomography (FDG PET/CT) can be used to identify and localize infection in patients with vascular graft infections (VGI). We aimed to evaluate the diagnostic accuracy of 18F-FDG PET/CT by defining thresholds for standardized uptake value (SUV) and tissue-to-background ratio (TBR) that would accurately identify the presence of vascular graft infection.

METHODS

Patients with suspected VGI were prospectively recruited and underwent 18F-FDG PET/CT scans. Diagnosis was based on clinical, laboratory and radiologic findings, and blinded to the results of the PET/CT scan. Receiver operator characteristics (ROC) curve analysis was done to determine optimal thresholds for SUV and TBR.

RESULTS

Our final cohort consisted of 28 patients with suspected VGI (mean±SD age 67±10 years, 61% men), of which 15 patients (54%) had definitive VGI. The cohort included 61% prosthetics grafts and 39% stent-grafts. The type of graft included in this study were biologic (4%), Dacron (64%) and Polytetrafluoroethylene (32%). The location of the implanted grafts were aortic (54%) and peripheral arterial reconstruction (46%). The location of the peripheral graft was 77% in lower extremity and 23% in the upper extremity (arterio-venous grafts for dialysis access). Using ROC analysis, SUV max of 4.5, SUV mean of 3.7, and a TBR of 1.6 gave the best balance between sensitivity and specificity (93%/92%, 100%/92% and 93%/92% respectively). All thresholds had an area under the curve ≥0.93 and correct reclassification rate ≥93%.

CONCLUSION

Our data suggests that FDG PET/CT can be used to reliably and accurately diagnose VGI. The dual anatomic-physiologic information from FDG PET/CT can complement clinical diagnosis particularly in uncertain cases.

Evidence-based guideline of the European Association of Nuclear Medicine (EANM) on imaging infection in vascular grafts

Purpose

Consensus on optimal imaging procedure for vascular graft/endograft infection (VGEI) is still lacking and the choice of a diagnostic test is often based on the experience of single centres. This document provides evidence-based recommendations aiming at defining which imaging modality may be preferred in different clinical settings and post-surgical time window.

Methods

This working group includes 6 nuclear medicine physicians appointed by the European Association of Nuclear Medicine, 4 vascular surgeons, and 2 radiologists. Vascular surgeons formulated 5 clinical questions that were converted into 10 statements and addressed through a systematic analysis of available literature by using PICOs (Population/problem–Intervention/Indicator–Comparator–Outcome) strategy. Each consensus statement was scored for level of evidence and for recommendation grade, according to the Oxford Centre for Evidence-based Medicine criteria.

Results

Sixty-six articles, published from January 2000 up to December 2021, were analysed and used for evidence-based recommendations.

Conclusion

Computed tomography angiography (CTA) is the first-line imaging modality in suspected VGEI but nuclear medicine modalities are often needed to confirm or exclude the infection. Positron emission tomography/computed tomography (PET/CT) with 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) has very high negative predictive value but it should be performed preferably at least 4 months after surgery to avoid false positive results. Radiolabelled white blood cell (WBC) scintigraphy, given its high diagnostic accuracy, can be performed at any time after surgery.

Preamble

The European Association of Nuclear Medicine (EANM) is a professional no-profit medical association that facilitates communication worldwide between individuals pursuing clinical and research excellence in nuclear medicine. The EANM was founded in 1985. EANM members are physicians, technologists, and scientists specializing in the research and practice of nuclear medicine. The EANM will periodically define new guidelines for nuclear medicine practice to help advance the science of nuclear medicine and to improve the quality of service to patients throughout the world. Existing practice guidelines will be reviewed for revision or renewal, as appropriate, on their fifth anniversary or sooner, if indicated. Each practice guideline, representing a policy statement by the EANM, has undergone a thorough consensus process in which it has been subjected to extensive review. The EANM recognizes that the safe and effective use of diagnostic nuclear medicine imaging requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guideline by those entities not providing these services is not authorized. These guidelines are an educational tool designed to assist practitioners in providing appropriate care for patients. They are not inflexible rules or requirements of practice and are not intended, nor should they be used, to establish a legal standard of care. For these reasons and those set forth below, the EANM suggests caution against the use of the current consensus document in litigation in which the clinical decisions of a practitioner are called into question. The ultimate judgement regarding the propriety of any specific procedure or course of action must be made by the physician or medical physicist in the light of all the circumstances presented. Thus, there is no implication that an approach differing from the consensus document, standing alone, is below the standard of care. To the contrary, a conscientious practitioner may responsibly adopt a course of action different from that set forth in the consensus document when, in the reasonable judgement of the practitioner, such course of action is indicated by the condition of the patient, limitations of available resources, or advances in knowledge or technology subsequent to publication of the consensus document. The practice of medicine includes both the art and the science of the prevention, diagnosis, alleviation, and treatment of disease. The variety and complexity of human conditions make it impossible to always reach the most appropriate diagnosis or to predict with certainty a particular response to treatment. Therefore, it should be recognized that adherence to this consensus document will not ensure an accurate diagnosis or a successful outcome. All that should be expected is that the practitioner will follow a reasonable course of action based on current knowledge, available resources, and the needs of the patient, to deliver effective and safe medical care. The sole purpose of this consensus document is to assist practitioners in achieving this objective.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-022-05769-x.

Primary aortoenteric fistula: A case report and brief review of the literature

Aortoenteric fistula is a life-threatening emergency and is associated with high morbidity and mortality. Prompt surgical intervention before the aneurysm ruptures lowers the mortality rate to about 50%. Potential imaging mimics for aortoenteric fistula include retroperitoneal fibrosis, mycotic aortic aneurysm, and infectious aortitis. Secondary aortoenteric fistula has relative higher incidence compared to primary and is more common with open aortic repair versus endovascular stent graft repair. Ectopic gas in the aneurysm sac and extravasation of enteric contrast into the aneurysm sac is diagnostic for aortoenteric fistula. However, enteric contrast is not recommended for routine evaluation of aortoenteric because the aforementioned finding is extremely rare. More common imaging findings include bowel loop appearing adherent to aneurysm sac with associated inflammatory stranding and foci or ectopic gas within the aneurysm sac or interposed between the bowel and aneurysm sac. Here we present a case of 52-year-old male who presents with incidental primary aortoenteric fistula.

Acute traumatic injury of the aorta: presentation, diagnosis, and treatment

Despite advances in detection and treatment, acute traumatic aortic injury (ATAI) is associated with high rates of morbidity and mortality. Both physical and hemodynamic forces have been postulated as mechanisms of aortic injury during a traumatic event. For patients who survive the initial injury, rapid detection is critical for diagnosis and procedural planning, which requires a thorough knowledge of both its clinical presentation and the available diagnostic imaging modalities. Radiography, computed tomography (CT), and magnetic resonance imaging (MRI) can each have a role in the diagnosis of ATAI. After stabilization of the patient, the management of ATAI is guided by the severity of injury. Appropriately selected patients with low grade injuries may be managed non-operatively. When treatment is required, there are both open surgical and endovascular options. In current practice, endovascular approaches with stent-graft placement are preferred due to their high clinical success and low rates of complications. Complications from endograft placement can include: endoleak, endograft collapse, infection, endograft failure, and endograft migration. Open surgical repair is now reserved for patients with unfavorable anatomy for endovascular therapies. This review provides a comprehensive overview of ATAI including its epidemiology and demographics, mechanisms of injury, clinical and radiographic diagnosis, treatment options, and post-therapeutic follow-up.

Prosthetic vascular graft infection: A systematic review and meta-analysis on diagnostic accuracy of 18FDG PET/CT

INTRODUCTION

There is a high risk of mortality and morbidity associated with Vascular Graft Infections (VGI) which requires early diagnosis. The aim of the present systematic review and meta-analysis was to evaluate the diagnostic accuracy, sensitivity and specificity of 18FDG PET/CT in diagnosing VGI.

METHODS

A systematic review was conducted according to the PRISMA guidelines through a search in Embase, PubMed, and Cochrane databases. We evaluated five parameters including specificity, sensitivity, negative and positive predictive values (NPV and PPV), and accuracy. We used STATA/MP 15.0 (StataCorp, College Station, TX) for all of our analyses.

RESULTS

Overall 10 studies including 320 patients undergone 18FDG PET/CT were included. The sensitivity, specificity, positive and negative likelihood ratios along with their 95% CI were 0.92 (95% CI 0.88-0.95), 0.76 (95% CI 0.76-0.70), 3.49 (95% CI 3.49-2.32) and 0.14 (95% CI 0.09-0.23), respectively. The diagnostic odds ratio (DOR) for diagnosis of VGI was 37.12 (95% CI 14.84-92.82). The mean cut-off value of the maximum standardized uptake value (SUVmax) for diagnosis of VGI was 5.39 while the overall mean SUVmax among patients with VGI was 8.47.

CONCLUSION

According to our results, 18FDG PET/CT is a useful diagnostic method in detecting active VGI with high diagnostic accuracy. Because of its ability to evaluate morphology and main texture using SUVmax, the 18FDG PET/CT provides an objective assessment of aspects and extent of disease activity, which results in preventing unnecessary surgery, proper treatment planning, and evaluating the effectiveness of treatment.

Gallium-67 Scan with Single Photon Emission Computed Tomography for the Evaluation and Monitoring of Infected Abdominal Aortic Aneurysms: A 10-Year Case Series

Purpose

This study aimed to evaluate the role of gallium-67 single photon emission computed tomography (SPECT) with contrast computed tomography (CT) in the evaluation and monitoring of infected abdominal aortic aneurysms (IAAA).

Methods

Materials and A retrospective cohort analysis was performed using prospectively collected data of consecutive patients with IAAA in Princess Margaret Hospital in Hong Kong between January 2010 and December 2020. The patients were identified using the Radiology Information System.

Results

All five patients had proven IAAA on CT and/or metabolic imaging. Among them, three were further supported by positive blood culture results. Gallium-67 SPECT with contrast CT was useful in the detection of residual disease, monitoring, and detection of recurrence.

Conclusion

Gallium-67 SPECT with contrast CT is helpful for evaluating IAAA. It serves an important role in guiding management, especially during long-term follow-up.

A systematic review and meta-analysis of 18F-fluoro-d-deoxyglucose positron emission tomography interpretation methods in vascular graft and endograft infection

OBJECTIVE

Vascular graft and endograft infection (VGEI) has high morbidity and mortality rates. Diagnosis is complicated because symptoms vary and can be nonspecific. A meta-analysis identified ¹⁸F-fluoro-d-deoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG PET/CT) as the most valuable tool for diagnosis of VGEI and favorable to computed tomography as the current standard. However, the availability and varied use of several interpretation methods, without consensus on which interpretation method is best, complicate clinical use. The aim of this study was to evaluate the diagnostic performance of different interpretation methods of ¹⁸F-FDG PET/CT in diagnosis of VGEI.

METHODS

A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data sources included PubMed/MEDLINE, Embase, and Cochrane Library. A meta-analysis was conducted on the different interpretation methods for ¹⁸F-FDG PET/CT in diagnosis of VGEI, including visual FDG uptake intensity, visual FDG uptake pattern, and quantitative maximum standardized uptake (SUVmax).

RESULTS

Of 613 articles, 13 were included (10 prospective and 3 retrospective articles). The FDG uptake pattern method (I² = 26.2%) showed negligible heterogeneity, whereas the FDG uptake intensity (I² = 42.2%) and SUVmax (I² = 42.1%) methods showed moderate heterogeneity. The pooled sensitivity for FDG uptake intensity was 0.90 (95% confidence interval [CI], 0.79-0.96); for uptake pattern, 0.94 (95% CI, 0.89-0.97); and for SUVmax, 0.95 (95% CI, 0.76-0.99). The pooled specificity for FDG uptake intensity was 0.59 (95% CI, 0.38-0.78); for FDG uptake pattern, 0.81 (95% CI, 0.71-0.88); and for SUVmax, 0.77 (95% CI, 0.63-0.87). The uptake pattern interpretation method demonstrated the best positive and negative post-test probability, 82% and 10%, respectively.

CONCLUSIONS

This meta-analysis identified the FDG uptake pattern as the most accurate assessment method of ¹⁸F-FDG PET/CT for diagnosis of VGEI. The optimal SUVmax cutoff, depending on the vendor, demonstrated strong sensitivity and moderate specificity.

Genuine impact of 18F-fluorodeoxyglucose positron emission tomography with contrast-enhanced computed tomography in clinching the diagnosis and follow-up response assessment of vascular graft infections

Vascular graft infection (VGI) is a rare and severe complication after vascular surgery associated with significant morbidity and mortality, but the diagnosis is not always straightforward due to its variable and nonspecific clinical signs. Computed tomography (CT) scan is considered to be the diagnostic tool of choice for advanced VGI, but there is a high incidence of false-negative results, especially in low-grade infections. ¹⁸F-Fluorodeoxyglucose positron emission tomography with contrast-enhanced CT (¹⁸F-FDG PET-CT) imaging can serve as an effective alternative tool for assessment of suspected VGI and also provide accurate anatomic localization of the infective focus. Here, we describe three cases of VGI with various clinical presentations where the site of infection was diagnosed, confirmed, and documented with the help of ¹⁸F-FDG PET-CT imaging.

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

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.

Aortoenteric fistulas: spectrum of MDCT findings

An aortoenteric fistula is an abnormal communication between the aorta and the gastrointestinal tract wall. The high mortality associated with this rare entity means it requires early accurate diagnosis. Aortoenteric fistulas are classified as primary when they develop on a native aorta that has not undergone an intervention and as secondary when they develop after vascular repair surgery. All radiologists need to be able to recognize the direct and indirect signs that might suggest the presence of an aortoenteric fistula. This article reviews the types of aortoenteric fistulas and their clinical and pathophysiological correlation, as well as the diagnostic algorithm, illustrating the most characteristic findings on multidetector computed tomography.

Diagnostic yield of 18F-FDG PET/CT in suspected diagnosis of vascular graft infection: A prospective cohort study

BACKGROUND

Prosthetic vascular graft infection (PVGI) is a severe complication associated with high morbidity and mortality. Clinical diagnosis is complex, requiring image testing such as CT angiography or leukocyte scintigraphy, which has considerable limitations. The aim of this study was to know the diagnostic yield of PET/CT with 18F-Fluorodeoxyglucose (18F-FDG) in patients with suspected PVGI.

METHODS

We performed a prospective cohort study including 49 patients with suspected PVGI, median age of 62 ± 14 years. Three uptake patterns were defined following published recommendations: (i) focal, (ii) patched (PVGI criteria), and (iii) diffuse (no PVGI criterion).

RESULTS

Sensitivity, specificity, and positive and negative predictive values for 18F-FDG-PET/CT were 88%, 79%, 67%, and 93%, respectively. 18F-FDG-PET/CT identified 14/16 cases of PVGI showing a focal (n = 10) or patched pattern (n = 4), being true negative in 26/33 cases with either a diffuse pattern (n = 16) or without uptake (n = 10). Five of the seven false-positive cases (71%) showed a patched pattern and all coincided with the application of adhesives for PVG placement.

CONCLUSIONS

18F-FDG-PET/CT is a useful technique for the diagnosis of PVGI. A patched pattern on PET/CT in patients in whom adhesives were applied for prosthetic vascular graft placement does not indicate infection.

Multimodality imaging of an aortic graft infection

Aortic prosthetic vascular graft infections (PVGI) are rare complications of the aortic surgery, with an incidence of 0.5%-6%. Although rare, they carry mortality rates as high as 25%-88%. Improvement in diagnostic imaging modalities in the last two decades, together with early diagnosis, aortic PVGI associated mortality was reduced. These imaging methods include transesophageal echocardiography (TEE), computed tomography angiography (CTA), and 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). In this case report, we focus mainly on three imaging modalities as TEE, CTA, and 18F-FDG PET/CT and showed their role in the assessment of aortic PVGI.

Psoas abscess associated with aortic endograft infection caused by bacteremia of Listeria monocytogenes: A case report and literature review (CARE Complaint)

RATIONALE

Endograft infection following endovascular stent for aortic aneurysm is rare (0.6%-3%), but it results in high mortality rate of 25% to 88%.

PATIENT CONCERNS

A 66-year-old hypertensive man underwent an endovascular stent graft for abdominal aortic aneurysm 18 months ago. Recurrent episodes of fever, chills, and abdominal fullness occurred 6 months ago before this admission. Laboratory data showed 20 mg/dL of C-reactive protein and abdominal computed tomography (CT) revealed an aortic endoleak at an urban hospital, so 4-day course of intravenous (IV) amoxicillin/clavulanic acid was given and he was discharged after fever subsided. He was admitted to our hospital due to fever, chills, and watery diarrhea for 1 day. Abdominal CT showed left psoas abscess associated with endograft infection. Blood culture grew Listeria monocytogenes.

DIAGNOSIS

Left psoas abscess associated with endograft infection caused by bacteremia of Listeria monocytogenes.

INTERVENTIONS

IV ampicillin with 8 days of synergistic gentamicin was prescribed and it created satisfactory response. Ampicillin was continued for 30 days and then shifted to IV co-trimoxazole for 12 days.

OUTCOMES

He remained asymptomatic with a decline of CRP to 0.36 mg/dL and ESR to 39 mm/h. He was discharged on the 44th hospital day. Orally SMX/TMP was prescribed for 13.5 months.

LESSONS

Only few cases of aortic endograft infection caused by Listeria monocytogenes had been reported. In selected cases, particularly with smoldering presentations and high operative risk, endograft retention with a prolonged antimicrobial therapy seem plausible as an initial therapeutic option, complemented with percutaneous drainage or surgical debridement if necessary.

Aortic reconstruction in infected aortic pathology by femoral vein "neo-aorta"

The use of autologous femoral veins for in situ reconstruction of the aortoiliac segment is an effective technique to treat native aorta or prosthetic graft infections. The indications, technical details, and outcomes of this procedure are detailed. Graft infection involving the aortic segment, while rare, remains one of the most challenging vascular surgery conditions to treat. The original technique of "neo-aortoiliac surgery" with in situ autologous vein grafts has evolved over the past 25 years and remains a worthwhile alternative for the treatment of aortic graft infections, with lower mortality rates compared with other extra-anatomic or in situ surgical options. Acceptance of this surgical option is due to low graft re-infection rates, rare graft disruption, and low long-term aneurysmal degeneration. Excision of the femoral veins is associated with acceptable rates of lower limb edema. The use of an autologous femoral vein graft can be considered the standard of care in selected patients for the management of aortic graft infections. Optimal management of patients with aortic graft infections requires consideration of all potential therapeutic options because no single modality can be used, and individualizing treatment according to the clinical condition will yield the best patient outcomes.

Ileal artery pseudoaneurysm: a rare cause of gastrointestinal bleed

Aorto-enteric fistulas are life-threatening conditions that occur commonly between the aorta and duodenum. Our case describes a fistula between the ileal artery and small bowel. To our knowledge, ileal artery fistulas are more commonly described in surgical cases, unlike our case. This case emphasizes early diagnosis of an aorto-enteric fistula causing life-threatening gastrointestinal bleeding to improve morbidity and survival.

Diagnostic Imaging in Vascular Graft Infection: A Systematic Review and Meta-Analysis

BACKGROUND

Vascular graft infection (VGI), a serious complication in vascular surgery, has a high morbidity and mortality rate. The diagnosis is complicated by non-specific symptoms and challenged by the variable accuracy of different imaging techniques. The objective of this study was to determine the diagnostic value of various imaging techniques to diagnose VGI.

METHODS

A systematic review was conducted according to the PRISMA guidelines. Data sources included PubMed/Medline, Embase, and Cochrane from January 1997 until October 2017. Observational cohort studies were included. A meta-analysis was conducted on several imaging modalities: computed tomography with or without angiography (CT(A)), ¹⁸F-fluoro-d-deoxyglucose positron emission tomography with or without low dose or contrast enhanced CT (FDG-PET(/CT)), and white blood cell scintigraphy with or without single photon emission computed tomography combined with low dose CT (WBC (SPECT/CT)).

RESULTS

Of 4259 papers, 14 articles were included, containing eight prospective and six retrospective articles. CTA (I² 7.4%), FDG-PET (I² 36.5%), and FDG-PET/CT (I² 36.6%) showed negligible to moderate heterogeneity, while WBC scintigraphy ± SPECT/CT (I² 78.6%) showed considerable heterogeneity. Pooled sensitivity for CTA was 0.67 (95% CI 0.57-0.75), in contrast to FDG-PET of 0.94 (95% CI 0.88-0.98), FDG-PET/CT of 0.95 (95% CI 0.87-0.99), WBC scintigraphy of 0.90 (95% CI 0.85-0.94), and WBC scintigraphy with SPECT/CT of 0.99 (95% CI 0.92-1.00). The pooled specificities were for CTA 0.63 (95% CI 0.48-0.76), FDG-PET 0.70 (95% CI 0.59-0.79), FDG-PET/CT 0.80 (95% CI 0.69-0.89), WBC scintigraphy 0.88 (95% CI 0.81-1.94), and WBC scintigraphy SPECT/CT 0.82 (95% CI 0.57-0.96). Pre- and post-test results showed that WBC SPECT/CT favours FDG-PET/CT, with a positive post-test probability of 96% versus 83%.

CONCLUSION

This meta-analysis suggests the diagnostic performance of WBC scintigraphy combined with SPECT/CT is the greatest in diagnosing VGI. However, it is a time consuming technique and not always available. Therefore FDG-PET/CT may be favourable as the initial imaging technique. The use of solitary CTA in diagnosing VGI seems to be obsolete.

Determining the Diagnostic Value of 18F-Fluorodeoxyglucose Positron Emission/Computed Tomography in Detecting Prosthetic Aortic Graft Infection

BACKGROUND

To determine the diagnostic value of 18F-fluorodeoxyglucose positron emission/computed tomography (FDG PET/CT) in detecting prosthetic aortic graft infection (AGI).

METHODS

Twenty-one patients with prosthetic grafts for abdominal aortic aneurysms underwent FDG PET/CT scans for suspected graft infection over a 15-month period. Images were evaluated for tracer pattern and grade of FDG uptake in addition to measuring the maximal standardized uptake value (SUVmax). Two independent nuclear medicine physicians retrospectively evaluated all imaging. The images from a control group of patients with aortic grafts who underwent FDG PET/CT scans for onco-hematological indications were evaluated to establish radiological characteristics of asymptomatic grafts. Secondary parameters that are associated with graft infection such as components of the peripheral blood count were collected. Graft infection status was determined using microbiological outcomes following graft explantation or radiological drainage of perigraft collections and correlated with results of the FDG PET/CT scans to determine infective status.

RESULTS

In the control group, the pattern of FDG uptake was homogenous and diffuse. The mean SUVmax was 3.5 (±1.3). Thirteen out of 21 grafts were confirmed as infected. Tracer uptake in infected grafts displayed an intense and focal pattern, with a median grade of uptake of 4 vs. 2 on a validated 4 point grading scale. The area under the receiver operating curve for FDG PET/CT in detecting infection was 0.85 (±0.15) P = 0.01. Sensitivity was 92%, specificity 63%, and positive and negative predictive values of 80% and 83%, respectively. The SUVmax was significantly higher in infected than noninfected grafts, (10.3 ± 4.2 vs. 5.4 ± 3.4) P = 0.02. According to the receiver operating characteristic analysis, SUVmax greater than 6.3 represented the optimal cutoff between infective and noninfective outcome. Of the secondary parameters collected, grade of uptake and SUVmax were the only significant predictors of infection (odds ratio 2.5, 1.5 respectively) P = 0.05. White cell count, erythrocyte sedimentation rate, and C-reactive protein demonstrated nonsignificant odds ratios of 1.4, 0.9, and 1.0, respectively.

CONCLUSIONS

FDG PET/CT is a valuable diagnostic test for identifying AGI. Infected grafts display significantly greater FDG uptake in a distinctive intense focal perigraft pattern and distribution. SUVmax greater than 6.3 is a good cutoff to determine infective status.

Complex treatment of vascular prostheses infections

Infections after vascular reconstructions are very rare; however, when they occur, they are associated with a high risk of morbidity. In order to obtain the best results possible, the treatment needs to be initiated as early as possible, from the very first signs of infection, and it needs to be carried out in centers specializing in vascular surgery. The aim of the present study was to assess the incidence of infections in a single university center.This retrospective analysis over a 2-year period is based on the medical reports of hospitalized patients who were diagnosed with infection following revascularization.From 2013 to 2014, a number of 151 open reconstructive surgical procedures were performed. 15 patients suffered from infection (10%) of the vascular reconstruction. Of these patients, 40% have had an aorto-bifemoral bypass, 53%-a femoro-popliteal bypass, and 7% (n = 1)-an axillo-femoral bypass. According to the Samson classification, the patients were categorized as follows: group 2: 6 cases, group 3: 2 cases, group 4: 4 cases, and group 5: 3 cases. The most frequent bacteria found were methicillin-resistant Staphylococcus aureus (MRSA) (n = 6, 40%), followed by S aureus (n = 5, 33%). The treatment options were: application of antibiotics alone without any invasive treatment in 3 patients, local irrigation and debridement in 6 patients, complete explantation of the prosthesis with a new extra-anatomic bypass in 6 cases, and partial excision of the prosthesis, which was replaced and covered with muscle flap, in 3 cases. The amputation rate in our study was 18%, which corresponds to the rates published in the literature.The treatment of infections in vascular surgery needs to be complex and adapted to each individual patient, because infections being in a permanent dynamic state. The treatment needs to be performed in specialized centers that have large experience in vascular surgery, in order for the patient to have the best chances of survival and protection from amputation.

Perigraft air mimicking infection on CT angiography following open abdominal aortic aneurysm repair

Aortic graft infection is a feared complication after open abdominal aortic aneurysm repair secondary to its high mortality. Perigraft air is a common finding after open aortic aneurysm repair; however, it is also associated with aortic graft infection. Delineating between graft infection and common postoperative finding is a challenge. This is further complicated by use of hemostatic agents such as Gelfoam, which is also documented to cause perigraft air. Correct diagnosis has crucial implications in management of potential aortic graft infection, which is a vascular emergency. We report a case of perigraft air in a patient status after open aortic aneurysm repair with associated clinical manifestations of infection in whom conservative management and surveillance was selected for treatment. We then discuss the timeline of perigraft air, potential causation, importance of history, and physical examination, and finally, we discuss how specific findings on computed tomography imaging for infection in other areas may be useful in aortic graft infection.

Complications of endovascular aneurysm repair of the thoracic and abdominal aorta: evaluation and management

In recent decades, endovascular aneurysm repair or endovascular aortic repair (EVAR) has become an acceptable alternative to open surgery for the treatment of thoracic and abdominal aortic aneurysms and other aortic pathologies such as the acute aortic syndromes (e.g., penetrating aortic ulcer, intramural hematoma, dissection). Available data suggest that endovascular repair is associated with lower perioperative 30-day all-cause mortality as well as a significant reduction in perioperative morbidity when compared to open surgery. Additionally, EVAR leads to decreased blood loss, eliminates the need for cross-clamping the aorta and has shorter recovery periods than traditional surgery. It is currently the preferred mode of treatment of thoracic and abdominal aortic aneurysms in a subset of patients who meet certain anatomic criteria conducive to endovascular repair. The main disadvantage of EVAR procedures is the high rate of post-procedural complications that often require secondary re-intervention. As a result, most authorities recommend lifelong imaging surveillance following repair. Available surveillance modalities include conventional radiography, computed tomography, magnetic resonance angiography, ultrasonography, nuclear imaging and conventional angiography, with computed tomography currently considered to be the gold standard for surveillance by most experts. Following endovascular abdominal aortic aneurysm (AAA) repair, the rate of complications is estimated to range between 16% and 30%. The complication rate is higher following thoracic EVAR (TEVAR) and is estimated to be as high as 38%. Common complications include both those related to the endograft device and systemic complications. Device-related complications include endoleaks, endograft migration or collapse, kinking and/or stenosis of an endograft limb and graft infection. Post-procedural systemic complications include end-organ ischemia, cerebrovascular and cardiovascular events and post-implantation syndrome. Secondary re-interventions are required in approximately 19% to 24% of cases following endovascular abdominal and thoracic aortic aneurysm repair respectively. Typically, most secondary reinterventions involve the use of percutaneous techniques such as placement of cuff extension devices, additional endograft components or stents, enhancement of endograft fixation, treatment of certain endoleaks using various embolization techniques and embolic agents and thrombolysis of occluded endograft components. Less commonly, surgical conversion and/or open surgical modification are required. In this article, we provide an overview of the most common complications that may occur following endovascular repair of thoracic and AAAs. We also summarize the current surveillance recommendations for detecting and evaluating these complications and discuss various current secondary re-intervention approaches that may typically be employed for treatment.

The "3M" Approach to Cardiovascular Infections: Multimodality, Multitracers, and Multidisciplinary

Cardiovascular infections are associated with high morbidity and mortality. Early diagnosis is crucial for adequate patient management, as early treatment improves the prognosis. The diagnosis cannot be made on the basis of a single symptom, sign, or diagnostic test. Rather, the diagnosis requires a multidisciplinary discussion in addition to the integration of clinical signs, microbiology data, and imaging data. The application of multimodality imaging, including molecular imaging techniques, has improved the sensitivity to detect infections involving heart valves and vessels and implanted cardiovascular devices while also allowing for early detection of septic emboli and metastatic infections before these become clinically apparent. In this review, we describe data supporting the use of a Multimodality, Multitracer, and Multidisciplinary approach (the 3M approach) to cardiovascular infections. In particular, the role of white blood cell SPECT/CT and [¹⁸F]FDG PET/CT in most prevalent and clinically relevant cardiovascular infections will be discussed. In addition, the needs of advanced hybrid equipment, dedicated imaging acquisition protocols, specific expertise for image reading, and interpretation in this field are discussed, emphasizing the need for a specific reference framework within a Cardiovascular Multidisciplinary Team Approach to select the best test or combination of tests for each specific clinical situation.

A Strange "Collection" after Surgery for an Aneurysm of the Popliteal Artery

The popliteal fossa is the site of several diseases that may be similar in the clinical setting but very different in etiology, treatment, and prognosis. The contemporary presentation of more than one of these conditions is a rare though potentially fatal combination that may lead to a delay in the diagnosis and therapeutic approach. In this report, we describe the case of a patient who presented at our Vascular Department for persistent pain and severe swelling of the right popliteal fossa 8 months after the surgical treatment of a symptomatic popliteal aneurysm by mean of a Dacron prosthetic graft. With the suspect of the graft infection, as defined by angio-computer tomography and fluorodeoxyglucose positron emission tomography, the patient underwent graft removal and revascularization with a biologic conduit. Subsequent surgical revisions for unjustified recurrent hematic collections were necessary without any significative clinical improvement. The histologic analysis of the removed tissue was consistent with a high-grade sarcoma, and the patient underwent above-the-knee amputation of the right limb.

Graft Infection Masquerading as Rheumatologic Disease: a Rare Case of Aortobifemoral Graft Infection Presenting as Hypertrophic Osteoarthropathy

BACKGROUND

Prosthetic vascular graft procedures are a common treatment modality for peripheral vascular disease. A relatively common complication is graft infection, occurring at a rate of 0.5-5%. When they occur, graft infections are associated with significant morbidity and mortality. Vascular graft infections also represent a diagnostic and therapeutic challenge for the physician METHODS: Here, we report a case where the rare finding of secondary hypertrophic osteoarthropathy was an important indication of underlying aortic graft infection that was initially misdiagnosed. A review of the literature revealed 34 cases of vascular graft infection associated with hypertrophic osteoarthropathy.

RESULTS

The mean interval from surgery to time of infection was approximately 5 years. Mortality was 35%. When combined with hypertrophic osteoarthropathy, vascular graft infection was complicated by an aortoenteric fistula in 53% of the cases.

CONCLUSION

The complexity of this case highlights the challenges physicians face in order to diagnose and treat this condition.

Cross-sectional imaging of aortic infections

Aortic infections are uncommon clinical entities, but are associated with high rates of morbidity and mortality. In this review, we focus on the cross-sectional imaging appearance of aortic infections, including aortic valve endocarditis, pyogenic aortitis, mycotic aneurysm and aortic graft infections, with an emphasis on CT, MRI and PET/CT appearance. Teaching Points • Aortic infections are associated with high morbidity and mortality. • CT, MRI and FDG PET/CT play complementary roles in aortic infection imaging. • Radiologists should be vigilant for aortic infection manifestations to ensure timely diagnosis.

Diagnosis of Abdominal Aortic Prosthesis Infection With FDG-PET/CT

A 79-year-old man was referred with recurrent periods of fever and chills. Six years earlier an aortic bifurcation graft had been implanted. Blood examination showed elevated infection parameters. A regular computed tomographic (CT) scan in the previous hospital showed no signs of graft infection. When blood cultures revealed multiple enteric bacteria, a 2-deoxy-2-[F18]fluoro- d-glucose-positron emission tomographic/CT (FDG- PET/CT) scan was performed that demonstrated ring-shaped pathological uptake at the proximal anastomosis. The patient was operated on and an infected graft was found, with a 1-cm defect in the distal part of the duodenum. Bacterial cultures of the explanted graft were positive. The patient recovered well from surgery and is on a regimen of prolonged antibiotic and antimycotic treatment.