Diagnostic Accuracy of PET/CT and Contrast Enhanced CT in Patients With Suspected Infected Aortic Aneurysms

Mycotic aortic aneurysms: characteristic macroscopic findings in a case series

Infected or mycotic aortic aneurysms (MAAs) are a rare type of aneurysms. Due to the high risk of rupture, MAAs are life-threatening conditions. Early diagnosis and treatment are necessary, yet MAAs are usually found coincidentally. We report 10 patients with MAAs in whom macroscopically, similar coined-sized lesions of the inner aortic wall were seen in all cases. When a coin-sized lesion in the inner aortic wall is seen during open surgical repair of an aortic aneurysm, the surgeon should consider an infectious cause. Microbiological tissue samples should be collected, and additional targeted antibiotic therapy should be started.

Unveiling cellular and molecular aspects of ascending thoracic aortic aneurysms and dissections

Ascending thoracic aortic aneurysm (ATAA) remains a significant medical concern, with its asymptomatic nature posing diagnostic and monitoring challenges, thereby increasing the risk of aortic wall dissection and rupture. Current management of aortic repair relies on an aortic diameter threshold. However, this approach underestimates the complexity of aortic wall disease due to important knowledge gaps in understanding its underlying pathologic mechanisms.Since traditional risk factors cannot explain the initiation and progression of ATAA leading to dissection, local vascular factors such as extracellular matrix (ECM) and vascular smooth muscle cells (VSMCs) might harbor targets for early diagnosis and intervention. Derived from diverse embryonic lineages, VSMCs exhibit varied responses to genetic abnormalities that regulate their contractility. The transition of VSMCs into different phenotypes is an adaptive response to stress stimuli such as hemodynamic changes resulting from cardiovascular disease, aging, lifestyle, and genetic predisposition. Upon longer exposure to stress stimuli, VSMC phenotypic switching can instigate pathologic remodeling that contributes to the pathogenesis of ATAA.This review aims to illuminate the current understanding of cellular and molecular characteristics associated with ATAA and dissection, emphasizing the need for a more nuanced comprehension of the impaired ECM-VSMC network.

Comprehensive literature review of oral and intravenous contrast-enhanced PET/CT: a step forward?

The integration of diagnostic CT scans into PET/CT facilitates a comprehensive single examination, presenting potential advantages for patients seeking a thorough one-shot check-up. The introduction of iodinated contrast media during PET scanning raises theoretical concerns about potential interference with uptake quantification, due to the modification of tissue density on CT. Nevertheless, this impact appears generally insignificant for clinical use, compared to the intrinsic variability of standardized uptake values. On the other hand, with the growing indications of PET, especially 18F-FDG PET, contrast enhancement increases the diagnostic performances of the exam, and provides additional information. This improvement in performance achieved through contrast-enhanced PET/CT must be carefully evaluated considering the associated risks and side-effects stemming from the administration of iodinated contrast media. Within this article, we present a comprehensive literature review of contrast enhanced PET/CT, examining the potential impact of iodinated contrast media on quantification, additional side-effects and the pivotal clinically demonstrated benefits of an all-encompassing examination for patients. In conclusion, the clinical benefits of iodinated contrast media are mainly validated by the large diffusion in PET protocols. Contrary to positive oral contrast, which does not appear to offer any major advantage in patient management, intravenous iodine contrast media provides clinical benefits without significant artifact on images or quantification. However, studies on the benefit-risk balance for patients are still lacking.

Significance and current approaches to vascular graft infection

Vascular graft/endograft infection (VGEI) is a constant in cardiovascular surgery with published rates between 1 and 5%. Every graft type and anatomical location is a potential target for infectious complications. These patients are sick patients with high frailty burden. Management of VGEI entails a multidisciplinary and multimodality approach. Here we review some aspects of the problem of VGEI including prevention, diagnosis, and surgical therapy with focus on recent developments in the field.

Cryopreserved Arterial Allografts Versus Rifampin-Soaked Dacron for the Treatment of Infected Aortic and Iliac Aneurysms

BACKGROUND

Infected aortic and iliac artery aneurysms are challenging to treat. Cryopreserved arterial allografts (CAAs) or rifampin-soaked Dacron (RSD) are standard options for in situ reconstruction. Our aim was to compare the safety and effectiveness of CAA versus RSD for these complex pathologies.

METHODS

This is a retrospective review of infected iliac, abdominal, and thoracoabdominal aortic aneurysms treated with either CAAs or RSD between 2002 and 2022 at our institution. The diagnosis was confirmed by intraoperative, radiologic, or microbiological evidence of aortic infection. Perioperative events, 30-day and long-term mortality, reinfection, and reintervention were analyzed.

RESULTS

Thirty patients (17 CAA, 13 RSD) with a mean age of 61 and 68 years, respectively, were identified. The infected aneurysm was most commonly suprarenal or infrarenal. Culture-negative infections were present in 47% of the CAA group and 54% in the RSD group. Early major morbidity was 57% and 54% for the CAA and RSD, respectively. Thirty-day mortality was similar between groups (18% vs. 23% CAA vs. RSD, P ≥ 0.99). Median follow-up was longer in the RSD group (14.5 months vs. 13 months). Overall survival at 1 and 5 years was 80.8% and 64.8% in the CAA group and 69.2% and 57.7% in the RSD group. Reinterventions only occurred with CAA repairs and indications included graft occlusion (2), multiple pseudoaneurysms and reinfection (1), and hemorrhagic shock caused by graft rupture (1). Freedom from reintervention at 1 and 3 years was 87.5% and 79.5% (CAA group) versus 100% and 100% (RSD, P = 0.06). Freedom from reinfection at 1 year was 100% in both groups, while at 3 years it was 90.9% for the CAA group and 100% for the RSD group (P = 0.39).

CONCLUSIONS

Infected aortic and iliac aneurysms have high early morbidity and mortality. CAA and RSD had similar outcomes in our series; CAA trended toward higher reintervention rates. Both remain viable options for complex scenarios but require close surveillance.

Vascular Complications in Coxiella burnetii Infection: A Report of Two Cases

Introduction

First described in 1937, Q fever remains a relatively new disease, with much to be learned about its presentation and diagnosis. Due to its role in the development of aortic aneurysms and vascular graft infections, its implications in the vascular domain have become increasingly reported. This is a report of two cases of vascular complications associated with Coxiella burnetii infection, and the challenges in managing their unique presentations.

Reports

Case 1: A 70 year old man with a prosthetic aortobiiliac graft and past Q fever infection presented with acute sepsis. Abdominal computed tomography (CT) showed soft tissue thickening and stranding around the graft, and locules of gas within the vessel. Pelvic magnetic resonance imaging (MRI) revealed a chain of abscesses within the right gluteal region, of which aspirate grew Prevotella oris and Escherichia coli. Open explanation of the aortic graft and replacement by superficial femoral vein was performed. Tissue culture confirmed a polymicrobial infection, and PCR of the aortic wall and pre-aortic lymph node was positive for Q fever. He was treated for recrudescent Q fever infection with a good outcome and recovery. Case 2: A 73 year old man had an incidental abdominal aortic aneurysm (AAA) identified at the time of Q fever diagnosis. Following an incomplete course of doxycycline and hydroxychloroquine, the aneurysm rapidly progressed, leading to presentation with right flank pain. Fluorodeoxyglucose (FDG) positron emission tomography (PET) showed multiple foci of uptake within the aneurysm wall. Open AAA repair with a polyester graft was performed, with AAA tissue positive for Q fever on PCR. The operation was successful, with the patient continuing clearance therapy at time of writing.

Discussion

Q fever infection poses serious implications for patients with vascular grafts and AAAs, and thus, should be considered in the differential diagnosis of mycotic aortic aneurysms and in aortic graft infections.

Infectious Aortic Aneurysm in a Patient With Leriche Syndrome

ABSTRACT

Leriche syndrome is a relatively rare atherosclerotic occlusive disease characterized by total occlusion of the abdominal aorta and/or both iliac arteries. The typical clinical manifestations of Leriche syndrome include intermittent claudication, fatigue, and leg pain. We present the case of a 56-year-old man with Leriche syndrome accompanied by an infectious abdominal aortic aneurysm. 18 F-FDG PET angiography/CT and 18 F-FDG PET/CT provided important information about the thrombus and infected sites.

Decisive diagnostic clue for infectious abdominal aortic aneurysm caused by Arthrobacter russicus in a diabetic elderly woman with renal dysfunction: A case report and literature review

Infectious aortic aneurysm (IAA) can be a rare but potentially fatal sequela of infectious inflammatory disease of the aortic wall with a high incidence of rupture. The definitive diagnosis is based on vascular imaging of the aneurysm using contrast-enhanced computed tomography (CE-CT) and identification of the causative microorganism from positive blood cultures (BCs). However, IAA remains extremely difficult to diagnose and treat in patients with prior antimicrobial treatment or with renal dysfunction. Here we describe a case of an 85-year-old woman with IAA caused by Arthrobacter russicus presenting with abdominal pain and fever that was initially diagnosed as a presumptive urinary tract infection and treated with empiric antimicrobial therapy. However, persistent abdominal pain with increased serological inflammation necessitated further evaluation. Unenhanced multimodality imaging considering the renal dysfunction revealed infectious aortitis of the infrarenal abdominal aorta, together with the initial culture results, leading to the tentative diagnosis of Klebsiella pneumoniae aortitis. Thereafter, serial monitoring with unenhanced magnetic resonance angiography (MRA) using thin-slab maximum intensity projection (TS-MIP) revealed acute aortic expansion strongly suggestive of a pseudoaneurysm that was successfully treated with early surgical repair under adequate infection control. Despite negative Gram staining and tissue culture results for the excised aortic wall, a definitive diagnosis of IAA secondary to A. russicus rather than K. pneumoniae was finally made by confirming the histologic findings consistent with IAA and the identification of A. russicus 16S rRNA on the resected aortic wall. The patient also developed a vascular graft infection during the postoperative course that required long-term systemic antimicrobial therapy. This case highlights the value of unenhanced MRA in the early detection of IAA in patients with renal dysfunction and the importance of a molecular diagnosis for identifying the causative microorganism in cases of culture- or tissue-negative IAA.

Imaging characteristics and diagnostic accuracy of FDG-PET/CT, contrast enhanced CT and combined imaging in patients with suspected mycotic or inflammatory abdominal aortic aneurysms

Purpose

To evaluate the diagnostic accuracy and specific imaging characteristics of positron emission tomography/computed tomography with 18F-fluorodeoxyglucose (PET/CT), contrast enhanced CT (CE-CT), and a combined imaging approach (CE-PET/CT) in patients with infectious/mycotic (MAA), inflammatory (IAA), and non-infected, non-inflammatory abdominal aortic aneurysm (AAA).

Materials and methods

In this single-center retrospective cohort study, all imaging data sets of 29 consecutive patients with clinically suspected MAA or IAA were anonymised with different, reshuffled identification numbers and retrospectively and independently analysed by two experienced readers, blinded to all clinical patient data. Readers determined the presence or absence and MAA, IAA and AAA and of predefined imaging characteristics (e.g. fluid collection), and measured metabolic activity and wall thickness of all aneurysms. A multidisciplinary team of specialists served as standard of reference and re-evaluated every clinical case, considering all clinical, laboratory, microbiological, histopathological and imaging results, including all follow-up examinations.

Results

Diagnostic accuracy was higher in PET/CT as compared to CE-CT in differentiating AAA from MAA and IAA: area under the receiver operating characteristic curve (AUC-ROC) 0.81 (95% confidence intervals 0.69–0.92) and 0.63 (0.52–0.74) (P = 0.027). Specific imaging characteristics were significantly associated with different types of aneurysms (P<0.05), i.e. very high metabolic activity and dorsal sparing of metabolic activity in PET/CT and wall thickening in CE-CT were indicative for IAA; fat stranding and fluid collections in CE-CT were associated with MAA; while low metabolic acitivity and absence of wall thickening in PET/CT, and less fat stranding and absence of wall thickening in CE-CT were indicative for non-infected, non-inflammatory AAA.

Conclusion

Specific imaging characteristics of PET/CT and CE-CT may be helpful in differentiating between MAA, IAA, and non-infected, non-inflammatory AAA.

Clinical and microbiological characteristics and challenges in diagnosing infected aneurysm: a retrospective observational study from a single center in Japan

Background

It is challenging to diagnose infected aneurysm in the early phase. This study aimed to describe the clinical and microbiological characteristics of infected aneurysm, and to elucidate the difficulties in diagnosing the disease.

Methods

Forty-one cases of infected aneurysm were diagnosed in Nagasaki University Hospital from 2005 to 2019. Information on clinical and microbiological characteristics, radiological findings, duration of onset, and type of initial computed tomography (CT) imaging conditions were collected. Factors related to diagnostic delay were analyzed by Fisher’s exact test for categorical variables or by the Wilcoxon rank-sum test for continuous variables.

Results

Pathogens were identified in 34 of 41 cases; the pathogens were Gram-positive cocci in 16 cases, Gram-negative rods in 13 cases, and others in five cases. Clinical characteristics did not differ in accordance with the identified bacteria. At the time of admission, 16 patients were given different initial diagnoses, of which acute pyelonephritis (n = 5) was the most frequent. Compared with the 22 patients with an accurate initial diagnosis, the 19 initially misdiagnosed patients were more likely to have been examined by plain CT. The sensitivities of plain CT and contrast-enhanced CT were 38.1% and 80.0%, respectively.

Conclusions

In cases of infected aneurysm, diagnostic delay is attributed to non-specific symptoms and the low sensitivity of plain CT. Clinical characteristics of infected aneurysm mimic various diseases. Contrast-enhanced CT should be considered if infected aneurysm is suspected.

Patient-tailored approach for diagnostics and treatment of mycotic abdominal aortic aneurysm

OBJECTIVE

The existing literature on mycotic aortic aneurysm is scarce and focuses on treatment. This study evaluates the clinical characteristics, diagnostics, treatment and outcome of patients with a mycotic abdominal aortic aneurysm treated in a tertiary referral center.

METHODS

A retrospective cohort study was conducted including all patients with a proven mycotic abdominal aortic aneurysm admitted between May 2010 and July 2020. Primary outcome was mortality and secondary outcome included complications such as vascular graft/endograft infection.

RESULTS

Twenty-four patients with a mycotic abdominal aortic aneurysm were included. Patients had a mean age of 68 ± 9 years and 20 (83%) were male. Thirteen patients (57%) had positive preoperative blood cultures. Streptococcus pneumoniae was most frequently isolated by blood culturing, pus, and vascular or perivascular tissue cultures (17%). In 19 (83%) patients the mycotic abdominal aortic aneurysm was located infrarenally, in three (13%) patients suprarenally, and in one (4%) patient juxtarenally. Median follow-up was 20 (7-42) months. In eight patients (33%) vascular graft and or endograft infection was diagnosed after surgical repair. Ten (42%) patients died during the follow-up period. The main causes of death were vascular graft/endograft infection-related (n=4) and rupture of the mycotic abdominal aortic aneurysm (n=3). No patient characteristics could be identified as predictive for mortality.

CONCLUSION

This study shows a large variation in presentation, diagnostic approaches, and surgical and antibiotic treatment of mycotic abdominal aortic aneurysm. The detailed information about the diagnostic approaches to this rare disease and its antibiotic/other treatment contributes to existing knowledge of mycotic abdominal aortic aneurysm. Because of the individual variation patients should be discussed in a multidisciplinary team with a vascular surgeon, infectious disease specialist, and clinical microbiologist.

MDCT Imaging of Non-Traumatic Thoracic Aortic Emergencies and Its Impact on Diagnosis and Management—A Reappraisal

Non-traumatic thoracic aorta emergencies are associated with significant morbidity and mortality. Diseases of the intimomedial layers (aortic dissection and variants) have been grouped under the common term of acute aortic syndrome because they are life-threatening conditions clinically indistinguishable on presentation. Patients with aortic dissection may present with a wide variety of symptoms secondary to the pattern of dissection and end organ malperfusion. Other conditions may be seen in patients with acute symptoms, including ruptured and unstable thoracic aortic aneurysm, iatrogenic or infective pseudoaneurysms, aortic fistula, acute aortic thrombus/occlusive disease, and vasculitis. Imaging plays a pivotal role in the patient’s management and care. In the emergency room, chest X-ray is the initial imaging test offering a screening evaluation for alternative common differential diagnoses and a preliminary assessment of the mediastinal dimensions. State-of-the-art multidetector computed tomography angiography (CTA) provides a widely available, rapid, replicable, noninvasive diagnostic imaging with sensitivity approaching 100%. It is an impressive tool in decision-making process with a deep impact on treatment including endovascular or open surgical or conservative treatment. Radiologists must be familiar with the spectrum of these entities to help triage patients appropriately and efficiently. Understanding the imaging findings and proper measurement techniques allow the radiologist to suggest the most appropriate next management step.

AAA Revisited: A Comprehensive Review of Risk Factors, Management, and Hallmarks of Pathogenesis

Despite declining incidence and mortality rates in many countries, the abdominal aortic aneurysm (AAA) continues to represent a life-threatening cardiovascular condition with an overall prevalence of about 2-3% in the industrialized world. While the risk of AAA development is considerably higher for men of advanced age with a history of smoking, screening programs serve to detect the often asymptomatic condition and prevent aortic rupture with an associated death rate of up to 80%. This review summarizes the current knowledge on identified risk factors, the multifactorial process of pathogenesis, as well as the latest advances in medical treatment and surgical repair to provide a perspective for AAA management.

Primary infectious aortic aneurysm: a case series and review of the literature

Abstract Infectious aneurysms, formerly known as mycotic aneurysms, are rare, most often involve the aorta in young patients, and have a greater tendency to rupture than aneurysms of other etiologies. The most characteristic shape is saccular and the most common etiologic agents are Staphylococcus sp. and Salmonella sp. There is scant and imprecise information in the literature about correct nomenclature, diagnosis, and treatment. The authors present three cases in which diagnostic and therapeutic procedures were documented. In addition to reporting this case series, the authors also present a review of the subject, outlining pertinent diagnostic and therapeutic strategies.

Aneurisma infeccioso primário da aorta: série de casos e revisão da literatura

Infectious aneurysms, formerly known as mycotic aneurysms, are rare, most often involve the aorta in young patients, and have a greater tendency to rupture than aneurysms of other etiologies. The most characteristic shape is saccular and the most common etiologic agents are Staphylococcus sp. and Salmonella sp. There is scant and imprecise information in the literature about correct nomenclature, diagnosis, and treatment. The authors present three cases in which diagnostic and therapeutic procedures were documented. In addition to reporting this case series, the authors also present a review of the subject, outlining pertinent diagnostic and therapeutic strategies.

Hyperinflammatory environment drives dysfunctional myeloid cell effector response to bacterial challenge in COVID-19

COVID-19 displays diverse disease severities and symptoms including acute systemic inflammation and hypercytokinemia, with subsequent dysregulation of immune cells. Bacterial superinfections in COVID-19 can further complicate the disease course and are associated with increased mortality. However, there is limited understanding of how SARS-CoV-2 pathogenesis and hypercytokinemia impede the innate immune function against bacterial superinfections. We assessed the influence of COVID-19 plasma hypercytokinemia on the functional responses of myeloid immune cells upon bacterial challenges from acute-phase COVID-19 patients and their corresponding recovery-phase. We show that a severe hypercytokinemia status in COVID-19 patients correlates with the development of bacterial superinfections. Neutrophils and monocytes derived from COVID-19 patients in their acute-phase showed an impaired intracellular microbicidal capacity upon bacterial challenges. The impaired microbicidal capacity was reflected by abrogated MPO and reduced NETs production in neutrophils along with reduced ROS production in both neutrophils and monocytes. Moreover, we observed a distinct pattern of cell surface receptor expression on both neutrophils and monocytes, in line with suppressed autocrine and paracrine cytokine signaling. This phenotype was characterized by a high expression of CD66b, CXCR4 and low expression of CXCR1, CXCR2 and CD15 in neutrophils and low expression of HLA-DR, CD86 and high expression of CD163 and CD11b in monocytes. Furthermore, the impaired antibacterial effector function was mediated by synergistic effect of the cytokines TNF-α, IFN-γ and IL-4. COVID-19 patients receiving dexamethasone showed a significant reduction of overall inflammatory markers in the plasma as well as exhibited an enhanced immune response towards bacterial challenge ex vivo. Finally, broad anti-inflammatory treatment was associated with a reduction in CRP, IL-6 levels as well as length of ICU stay and ventilation-days in critically ill COVID-19 patients. Our data provides insights into the transient functional dysregulation of myeloid immune cells against subsequent bacterial infections in COVID-19 patients and describe a beneficial role for the use of dexamethasone in these patients.

Impact of PET/CT among patients with suspected mycotic aortic aneurysms

Purpose

To determine the impact of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) on clinical management in patients with suspected mycotic aortic aneurysms (MAA).

Materials and methods

For this observational cohort study 101 PET/CT were acquired in 50 patients, thereof 50 for the initial diagnosis/baseline scan, 51 for follow-up. Impact on patient management was defined in three categories: PET/CT results were “confirmed” (by clinical follow-up), “suspected” (conclusive, not confirmed), or “misleading” (proven wrong by follow-up). For clinical follow-up patient data were recorded at the time of imaging, and at the latest recorded clinical visit. It included patient demographics, clinical information, laboratory data, results of microbiology and other diagnostic procedures, information about treatment, and patient’s general health condition.

Results

In four patients (8%) no clinical follow-up was feasible, the other 46 patients were clinically followed for a median of 898 days (IQR 320–4105). The combined evaluation of all 101 PET/CT demonstrated an impact on patient management in 78,5% of cases (48,5% confirmed, 30% suspected). Results of 21,5% of the PET/CT examinations were misleading. Respective values at baseline and at follow-up were: impact on patient management in 82% and 74,5% (70% and 27.5% confirmed, and 12% and 47% suspected), misleading cases in 18% and 25.5%.

Conclusion

In MAA, PET/CT has a high impact on patient management, which is more pronounced with baseline than with follow-up examinations. However, PET/CT results may be misleading in a smaller proportion of cases.

Impact of unknown incidental findings in PET/CT examinations of patients with proven or suspected vascular graft or endograft infections

Vascular graft or endograft Infections (VGEI) are rare but severe complications of vascular reconstructive surgery, and associated with significant mortality and morbidity risk. Positron emission tomography/computed tomography with ¹⁸F-fluorodeoxyglucose (PET/CT) has been shown to have a high diagnostic accuracy in the detection of VGEI. In this single-center prospective cohort study, we assessed the rate and the impact on patient management of relevant unknown incidental findings in PET/CT of patients with proven or suspected VGEI, and clinical follow-up of all patients was performed. Our study results show a comparably high rate of relevant unknown incidental findings (181 in 502 examinations), with documented direct impact on patient management in 80 of 181 (44%) of all findings. PET/CT scan- and patient-based evaluation revealed impact on patient management in 76 of 502 (17%) of all PET/CT scans, and in 59 of 162 (36%) of all patients, respectively. Furthermore, PET/CT correctly identified the final diagnosis in 20 of 36 (56%) patients without VGEI. In conclusion, in proven and suspected VGEI, PET/CT detects a high rate of relevant unknown incidental findings with high impact on patient management.

Imaging features of mycotic aortic aneurysms

Infectious aortitis (IA) is a rare and life-threatening cardiovascular disease. Early diagnosis and timely intervention are crucial for reducing mortality associated with mycotic aortic aneurysms (MAAs); however, early diagnosis is challenging due to the nonspecific symptoms. Some cases are diagnosed at an advanced stage or after developing complications, such as rupture or aortic fistula. Current state-of-the-art imaging modalities-including computed tomography (CT), magnetic resonance imaging (MRI), and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT-can detect infected aneurysms in clinically suspicious cases. MAA features on imaging include lobulated pseudoaneurysm, indistinct irregular arterial wall, perianeurysmal gas, perianeurysmal edema, perianeurysmal soft tissue mass, aneurysmal thrombosis, and high metabolic activity with increased uptake of FDG. Enlarged lymph nodes are often found adjacent to the aneurysm, while iliopsoas abscess (IPA), spondylitis, and aortic fistulas are commonly associated complications. After surgery or endovascular repair, radiological features-including ectopic gas, peri-graft fluid, thickening of adjacent bowel, pseudoaneurysm formed at the graft anastomosis, and increased uptake of FDG-may indicate an infection of aortic graft. This article provides an overview of the clinical and imaging features of MAAs. Thus, familiarity with the imaging appearances of MAAs may assist radiologists in the diagnosis and facilitation of timely treatment.

PET/CT in therapy control of infective native aortic aneurysms

Infective native aortic aneurysms (INAA) are aneurysms arising from infection of the aortic wall. Treatment is demanding with 5-year survival rates between 53 and 55%. The aim of our study was to evaluate the usefulness of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) in the long-term monitoring of patients with proven INAA. Fifty-three PET/CT were performed in 15 patients with INAA in this single-center retrospective cohort study and retrospective analysis of prospectively collected Vascular Graft Cohort Study (VASGRA) data. Median metabolic activity (as measured by maximum standardized uptake value, SUVmax) of the aneurysms at the initial PET/CT was high (6.8 (IQR 5.7–21.8)), and lower at the last PET/CT prior to the end of antimicrobial therapy (3.9 (IQR 2.7–6.8); n = 11) as well as in the first PET/CT after the end of the treatment (3.9 (IQR 3.0–4.4);n = 6). Compared to the course of C-reactive protein alone, PET/CT provided different (> 20% difference in trend) or altering (opposed trend) information on the course of disease in at least 14 comparisons (56%) in 11 patients (73%). The one-year and five-year freedom from all-cause lethality was 92% (95% confidence interval 57%-99%). As compared to the course of C-reactive protein, PET/CT provides different and occasionally altering information in therapy control of INAA.

The value of 18F-FDG-PET-CT in the management of infective native aortic aneurysms

OBJECTIVE

The objective of this systematic literature review was to explore the value of positron emission tomography combined with low-dose computed tomography (18F-FDG-PET-CT) in the diagnostics of infective native aortic aneurysm (INAA).

METHODS

A systematic literature review was performed using the search terms mycotic- and infected aortic aneurysms in Medline and Sciencedirect databases, published between 1 January 2000 and 1 January 2020. Using the PRISMA statement, articles were scrutinized according to a predefined protocol including: timing of 18F-FDG-PET-CT examination, the maximum standardized uptake value (SUVmax), additional findings on examination, and findings on repeated scanning of 18F-FDG-PET-CT.

RESULTS

Four studies were included in the analysis, comprising a total of 11 patients. Two studies were single case reports, and two were small case series, all were graded to be of low quality with high risk of bias. All patients were examined with a preoperative 18F-FDG-PET-CT, and 10 (91%) had increased 18F-FDG uptakes. The median SUVmax value was 6.53, range 4.46-9.23. The mean duration of antibiotic therapy prior to 18F-FDG-PET-CT was not known. Two patients were examined with repeated 18F-FDG-PET-CT examinations after treatment, where a decrease in SUVmax values could be demonstrated after successful treatment.

CONCLUSION

The literature on 18F-FDF-PET/CT for diagnosing infective native aortic aneurysms is scarce. However, there might be a role for 18F-FDF-PET/CT in the management of the disease, in particular for patients with clinical suspicion of INAA without convincing findings on CT. SUVmax values ranging from 4.5 to 6.5 could be guiding and suggestive of metabolic activity in agreement of INAA. However, further conclusions on its usefulness, robustness and specific SUVmax values are premature, and a definitive cut-off value is probably not attainable.