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E2345. Early Detection of Aorto-femoral Graft Late Occlusion: Can 18-F NaF PET-CT Be an Efficacious Modality?
Authors
  1. Khoan Thai; Hartford Hospital
Objective:
To systematically evaluate data on 18-F NaF PET-CT as a monitoring modality for early detection of progressive atherosclerosis, a principle cause of late occlusion in aorto-femoral grafts.

Materials and Methods:
MEDLINE and EMBASE were systematically searched up to June 2020. Included studies were published in the English language with reported data on 18-F NaF PET-CT as a method to detect active progressive atherosclerosis. Case reports, experimental and animal studies were excluded. Extracted data included demographics, risk factors and localization of 18-F NaF radiotracer on atheromatous calcification. Where possible, data were pooled and analyzed.

Results:
The pooled data from three studies examined 2,778 calcified atheromas and 394 sites with 18-F NaF tracer uptake. Colocalization of abnormal radiotracer uptake with calcified atheromas occurred at 336 sites 85.3% of the abnormal radiotracer uptake sites 12.1% of calcified atheromas. Two studies stratified the different types of atheromas: Positive correlations between radiotracer uptake and mild/medium calcification (p <0. 01). One study demonstrated highest coronary 18F-NaF uptake in the culprit plaques of myocardial infarction patients (p <0.0001) and plaque ruptures with associated histological evidence of active calcification and necrosis. One study specifically showed correlation with the calcium scores <1000 (p = 0. 001) but not for scores >1000.

Conclusion:
18-F NaF PET-CT is an efficacious monitoring modality of active progressive atherosclerosis, a mechanism causing late occlusion in aorto-femoral grafts. This modality has the ability to identify pathologically high-risk nascent microcalcification and provide highly relevant information about the state of calcified plaque before structural calcification is detectable by standard CT techniques. Once detected early, prompt therapies can be instituted to prevent late occlusion in high-risk patients with aorto-femoral grafts. In a prospective study on 3623 aortofemoral bypass procedures, approximately 2% of the grafts failed due to late occlusions causing 12% attributable mortality rate (Bredahl 2015). Unlike other complications, late occlusions can be treated if detected early. However, current diagnostic methods cannot detect until at late stage. Once detected at their late stage, the grafts are doomed to fail. Thus, a diagnostic method to detect early manifestation of late occlusion will be extremely beneficial in preventing this complication.