Contribution to FDG-PET/CT diagnostics and post-operative monitoring of patients with mycotic aneurysm of the thoracic aorta

Eccentric saccular aneurysm formation of the infrarenal aorta from an arterial wall tear

Eccentric saccular aneurysms result from a focal weakness of the arterial wall that may be due to a focal tear or a partial disruption of the arterial wall. Saccular morphology itself is often used as a factor for immediate intervention, because the risk of rupture is higher than that of the common fusiform aneurysms. We present a case of a 72-year-old female patient with a huge saccular aneurysm of the infrarenal aorta. In this case report, we discuss the algorithm that can be used for the differential diagnosis of any saccular shape aneurysm and that the main parameter that needs to be clarified before the endovascular treatment of any saccular aneurysm is the presence or absence of infection of the arterial wall.

Vascular findings on FDG PET/CT

Since its introduction into clinical practice, 2-deoxy-2-[18F]flu-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) has become firmly established in the field of oncological imaging, with a growing body of evidence demonstrating its use in infectious and inflammatory vascular pathologies. This pictorial review illustrates the utility of FDG PET/CT as a diagnostic tool in the investigation of vascular disease and highlights some of the more common incidental vascular findings that PET reporters may encounter on standard oncology FDG PET/CTs, including atherosclerosis, large vessel vasculitis, complications of vascular grafts, infectious aortitis and acute aortic syndromes.

Long-term outcome of endovascular aortic repair for mycotic abdominal aortic aneurysm

BACKGROUND

This study aimed to evaluate the feasibility and efficacy of endovascular treatment for mycotic abdominal aortic aneurysm (AAA) with long-term follow-up time period.

METHODS

Patients with mycotic AAA treated with endovascular aortic repair between January 2009 and December 2017 were included in this study. The preoperative and long-term outcomes during follow-up were reviewed and analysed.

RESULTS

Sixteen patients (12 males and four females with a mean age of 57.6 ± 14.1 years) were included in this study. The technical success rate was 100%. There were no preoperative mortalities, and one instance of deep venous thrombosis during hospitalization was recorded. The median follow-up time period was 41.2 (interquartile range 24.8-69.7) months, and the late mortality rate was 12.5%. Three (18.8%) patients presented with reinfection during follow-up. One patient presented with abdominal abscess and recurrent juxtarenal aortic aneurysm at 40 months post-operatively, and he received hybrid surgery and abdominal debridement and drainage. One patient developed staphylococcal bloodstream sepsis at 3 months post-operatively and the other patient developed Salmonella bloodstream sepsis at 9 months post-operatively. Pathogenic bacteria were consistent with the previous results. They both recovered after 2 months of intravenous antibiotic treatment. At present, all three patients are still alive without endograft infection and receiving outpatient follow-up. The aneurysm diameter decreased by more than 5 mm among five patients and remained stable in 10 patients at 1 year post-operatively.

CONCLUSION

Endovascular aortic repair is a feasible and effective method of treating mycotic AAA with an acceptable reinfection rate from our single-centre experience.

Metabolic Imaging as a Novel Strategy in Evaluation of Mycotic Abdominal Aortic Aneurysm: A Case Report and Brief Clinical Review

Abdominal aortic aneurysm (AAA) is an uncommon entity with high mortality. Etiologically, they are classified as inflammatory and infective (mycotic), the latter being less common. Clinical presentation, laboratory investigations, and treatment for these may considerably overlap. However, choice of management and the need for surgical intervention depends on factors such as size and progression of aneurysm, persistent symptoms, and presence or absence of distant pathology. Although computed tomography (CT) is the gold standard for AAA, in selected cases, especially in infected AAA, fluorodeoxyglucose positron emission tomography-CT can provide valuable information.

Vascular graft infections and role of PET/CT in patients with persistent bacteraemia

Prosthetic vascular graft infection although a rare complication of vascular reconstruction surgery; has been associated with significant morbidity and mortality. The author presents two patients with prosthetic aortic graft presenting as fever and methicillin sensitive Staphylococcus aureus bacteraemia without any other localising sign of infection. Both patients had a history of postoperative wound infection after their graft placement. Patients remained persistently bacteraemic on appropriate antimicrobial therapy making the clinician suspicious of a vascular graft infection. A [18 F] fluoro-2-deoxy-d glucose positron emission tomography associated to CT scan was used to identify the prosthetic vascular graft infection and since both patients were high-risk surgical candidates, a conservative medical approach was used. They were treated with 6 weeks of nafcillin and rifampin, followed by long-term doxycycline for suppression. This highlights the importance of considering vascular graft infection in patients with recurrent and persistent bacteraemia despite adequate therapy.

FDG Uptake Pattern on PET/CT Imaging in Non-Infectious Graft of a Patient with Operated Abdominal Aortic Aneurysm

Positron emission tomography using fluorodeoxyglucose is a well known diagnostic tool for routine assessment of the patients with carcinoma. Fluorodeoxyglucose uptake, as a marker of glucose metabolism, is increased in malignant conditions as well as infectious and inflammatory processes. In this case report, findings of postoperative changes in the graft on FDG PET/CT were presented in a patient on follow-up for operated renal cell carcinoma and aortic aneurysm graft surgery. The importance of the FDG uptake pattern has been pointed out for differential diagnosis of infectious and non-infectious conditions.

CONFLICT OF INTEREST

None declared.

PET/CT imaging in infectious conditions

New aggressive pathogens are responsible for the increasing incidence and difficult management of infections. Modern epidemics such as diabetes are frequently complicated by severe infections with subsequent high morbidity. Diagnosis (essentially early detection of infection) and also management decision making pose clinical challenges. Many resources are invested in developing precise, noninvasive diagnostic tests and efficient therapies for infectious processes. Nuclear medicine procedures are part of the evaluation armamentarium of patients with suspected or confirmed infection. Their strength relies on the fact that they are noninvasive tests that provide both functional as well as metabolic information early in the course of disease. Their limitations relate to the need for specific radiotracers and the rather low resolution of images. These limitations have been largely overcome by the hybrid PET/CT and SPECT/CT technology. PET/CT, primarily using FDG, is redefining the diagnostic work up and is currently leading to changes in the management of patients with suspected or known infections. The main indications for FDG PET/CT in infection, as well as updated literature results, are presented in the following review.