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

PET-Based Imaging with 18F-FDG and 18F-NaF to Assess Inflammation and Microcalcification in Atherosclerosis and Other Vascular and Thrombotic Disorders

Positron emission tomography (PET) imaging with ¹⁸F-fluorodeoxyglucose (FDG) represents a method of detecting and characterizing arterial wall inflammation, with potential applications in the early assessment of vascular disorders such as atherosclerosis. By portraying early-stage molecular changes, FDG-PET findings have previously been shown to correlate with atherosclerosis progression. In addition, recent studies have suggested that microcalcification revealed by ¹⁸F-sodium fluoride (NaF) may be more sensitive at detecting atherogenic changes compared to FDG-PET. In this review, we summarize the roles of FDG and NaF in the assessment of atherosclerosis and discuss the role of global assessment in quantification of the vascular disease burden. Furthermore, we will review the emerging applications of FDG-PET in various vascular disorders, including pulmonary embolism, as well as inflammatory and infectious vascular diseases.

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.

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.

Aortoenteric fistula secondary to an Inflammatory Abdominal Aortic Aneurysm

Primary aortoenteric fistulas are rare, with the annual incidence of such fistulas estimated to be 0.007 per million. The most common predisposing conditions for primary aortoenteric fistulas are atherosclerotic abdominal aortic aneurysms or penetrating atherosclerotic ulcers. We illustrate a rare case of an inflammatory aortic aneurysm causing a primary aortic fistula, with a direct fistulous jet from the aorta to the bowel with resultant catastrophic bleeding. In contrast to atherosclerotic aneurysms, most inflammatory aneurysms are symptomatic and show dense perianeurysmal fibrosis and periaortic wall thickening. A direct jet of contrast extravasation from the aorta into a bowel loop, while rarely seen, remains the most specific sign of a primary aorta-enteric fistula. A comprehensive literature review of the clinical presentation, imaging features, and differential diagnosis of a primary aortoenteric fistula are also discussed.