Increased fluorodeoxyglucose uptake following endovascular abdominal aortic aneurysm repair: a predictor of endoleak?

Prospect of positron emission tomography for abdominal aortic aneurysm risk stratification

Abdominal aortic aneurysm (AAA) disease is characterized by an asymptomatic, permanent, focal dilatation of the abdominal aorta progressing towards rupture, which confers significant mortality. Patient management and surgical decisions rely on aortic diameter measurements via abdominal ultrasound surveillance. However, AAA rupture can occur at small diameters or may never occur at large diameters, implying that anatomical size is not necessarily a sufficient indicator. Molecular imaging may help identify high-risk patients through AAA evaluation independent of aneurysm size, and there is the question of the potential role of positron emission tomography (PET) and emerging role of novel radiotracers for AAA. Therefore, this review summarizes PET studies conducted in the last 10 years and discusses the usefulness of PET radiotracers for AAA risk stratification. The most frequently reported radiotracer was [18F]fluorodeoxyglucose, indicating inflammatory activity and reflecting the biomechanical properties of AAA. Emerging radiotracers include [18F]-labeled sodium fluoride, a calcification marker, [64Cu]DOTA-ECL1i, an indicator of chemokine receptor type 2 expression, and [18F]fluorothymidine, a marker of cell proliferation. For novel radiotracers, preliminary trials in patients are warranted before their widespread clinical implementation. AAA rupture risk is challenging to evaluate; therefore, clinicians may benefit from PET-based risk assessment to guide patient management and surgical decisions.

18F-FDG PET/CT Detected Delayed Endoleak in an Aortoiliac Endovascular Aneurysm Repair

We present a case of a type Ia endoleak detected using F-FDG PET/CT 10 years after an abdominal aortoiliac endovascular aneurysm repair in an 83-year-old man. The F-FDG PET/CT scan was performed to evaluate a solitary pulmonary nodule but, in addition, demonstrated unexpected blood pool activity outside the stent graft and within the abdominal aortic aneurysm sac, indicating an endoleak; no FDG activity should be present within the aneurysm sac after stent graft placement. A subsequent CT angiogram confirmed the endoleak. This case illustrates the value of PET/CT in unexpectedly demonstrating this serious, late complication of endovascular aneurysm repair.

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.

Aneurysm sac shrinkage after endovascular treatment of the aorta: Beyond sac pressure and endoleaks

The isolation of the aneurysm sac from systemic pressure and its consequent shrinkage are considered criteria of success after endovascular repair (EVAR). However, the process of shrinkage does not solely depend on the intrasac pressure, the predictive role of which remains ambiguous. This brief review summarizes the additional pathophysiological mechanisms that regulate the biomechanical properties of the aneurysm wall and may interfere with the process of aneurysm sac shrinkage.