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Original research
Greater aortic inflammation and calcification in abdominal aortic aneurysmal disease than atherosclerosis: a prospective matched cohort study
  1. Nikhil V Joshi1,
  2. Maysoon Elkhawad2,
  3. Rachael O Forsythe1,
  4. Olivia M B McBride1,
  5. Nikil K Rajani2,
  6. Jason M Tarkin2,
  7. Mohammed M Chowdhury3,
  8. Emma Donoghue1,
  9. Jennifer M J Robson1,
  10. Jonathan Boyle3,
  11. Tim D Fryer4,
  12. Yuan Huang2,
  13. Zhongzhao Teng2,
  14. Marc R Dweck1,
  15. Ahmed A Tawakol5,
  16. Jonathan H Gillard4,
  17. Patrick A Coughlin3,
  18. Ian B Wilkinson6,
  19. David E Newby1 and
  20. James H F Rudd2
  1. 1Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
  2. 2Division of Cardiovascular Medicine, University of Cambridge, Cambridge, UK
  3. 3Department of Vascular Surgery, University of Cambridge, Cambridge, United Kingdom
  4. 4Wolfson Brain Imaging Centre, University of Cambridge, Cambridge, United Kingdom
  5. 5Harvard University, Cambridge, Massachusetts, USA
  6. 6Department of Medicine, University of Cambridge, Cambridge, United Kingdom
  1. Correspondence to Dr James H F Rudd; jhfr2{at}cam.ac.uk

Abstract

Objective Using combined positron emission tomography and CT (PET-CT), we measured aortic inflammation and calcification in patients with abdominal aortic aneurysms (AAA), and compared them with matched controls with atherosclerosis.

Methods We prospectively recruited 63 patients (mean age 76.1±6.8 years) with asymptomatic aneurysm disease (mean size 4.33±0.73 cm) and 19 age-and-sex-matched patients with confirmed atherosclerosis but no aneurysm. Inflammation and calcification were assessed using combined 18F-FDG PET-CT and quantified using tissue-to-background ratios (TBRs) and Agatston scores.

Results In patients with AAA, 18F-FDG uptake was higher within the aneurysm than in other regions of the aorta (mean TBRmax2.23±0.46 vs 2.12±0.46, p=0.02). Compared with atherosclerotic control subjects, both aneurysmal and non-aneurysmal aortae showed higher 18F-FDG accumulation (total aorta mean TBRmax2.16±0.51 vs 1.70±0.22, p=0.001; AAA mean TBRmax2.23±0.45 vs 1.68±0.21, p<0.0001). Aneurysms containing intraluminal thrombus demonstrated lower 18F-FDG uptake within their walls than those without (mean TBRmax2.14±0.43 vs 2.43±0.45, p=0.018), with thrombus itself showing low tracer uptake (mean TBRmax thrombus 1.30±0.48 vs aneurysm wall 2.23±0.46, p<0.0001). Calcification in the aneurysmal segment was higher than both non-aneurysmal segments in patients with aneurysm (Agatston 4918 (2901–8008) vs 1017 (139–2226), p<0.0001) and equivalent regions in control patients (442 (304-920) vs 166 (80-374) Agatston units per cm, p=0.0042).

Conclusions The entire aorta is more inflamed in patients with aneurysm than in those with atherosclerosis, perhaps suggesting a generalised inflammatory aortopathy in patients with aneurysm. Calcification was prominent within the aneurysmal sac, with the remainder of the aorta being relatively spared. The presence of intraluminal thrombus, itself metabolically relatively inert, was associated with lower levels of inflammation in the adjacent aneurysmal wall.

  • AAA
  • PET-CT
  • aneurysms
  • atherosclerosis
https://creativecommons.org/licenses/by/4.0/

This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See: https://creativecommons.org/licenses/by/4.0/.

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Footnotes

  • Twitter @nvjoshi00, @@jhfrudd

  • NVJ and ME contributed equally.

  • Contributors All authors contributed to the study.

  • Funding Funding was provided by the British Heart Foundation, The Evelyn Trust and the Academy of Medical Sciences. JHFR is supported by the NIHR Cambridge Biomedical Research Centre, HEFCE, the British Heart Foundation, the Wellcome Trust and the EPSRC Cambridge Mathematics In Healthcare Centre.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval The study was performed in accordance with the protocol approved by the local research ethics committee and the Declaration of Helsinki.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Study data are available on reasonable request, subject to ethics board approval.

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