Specific features to differentiate Giant cell arteritis aortitis from aortic atheroma using FDG-PET/CT

Area of Science:

• Nuclear Medicine
• Vascular Imaging
• Inflammatory Diseases

Background:

• ¹⁸F-fluorodeoxyglucose (FDG)-uptake in the aorta can be difficult to differentiate between aortitis and atheroma.
• This diagnostic challenge is particularly problematic for giant-cell arteritis (GCA) in elderly patients.

Purpose of the Study:

• To compare FDG uptake characteristics in GCA aortitis versus aortic atheroma using FDG-PET/CT.
• To identify distinguishing features of FDG uptake between these two aortic conditions.

Main Methods:

• Compared FDG aortic uptake in 29 GCA aortitis patients and 66 aortic atheroma patients.
• Utilized visual grading (grade 3 uptake) and semi-quantitative analyses (SUV_max, ∆SUV, TBRs) of FDG uptake.
• Analyzed FDG uptake across 5 aortic segments and peripheral arteries.

Main Results:

• Grade 3 FDG uptake was observed in 79.3% of GCA aortitis patients, but none with atheroma (p < 0.0001).
• FDG uptake in all 5 aortic segments (72.4%) and supra-aortic trunk (82.8%) was significantly higher in GCA aortitis.
• All semi-quantitative metrics (SUV_max, ∆SUV, TBRs) were significantly elevated in the GCA aortitis group, with ∆SUV showing the largest difference.

Conclusions:

• Specific FDG-PET/CT findings, including grade 3 aortic wall uptake, involvement of all 5 aortic segments, and peripheral artery uptake, can distinguish GCA aortitis from aortic atheroma.
• FDG-PET/CT offers valuable imaging biomarkers for differentiating these conditions, aiding in clinical diagnosis.
• Delta SUV (∆SUV) emerged as a key metric for differentiating GCA aortitis from aortic atheroma.