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SAT0340 Distinct Distribution Patterns of Large Vessel Vasculitis Assessed with 18f-FDG PET/CT: A Cluster and Principal Component Analysis Study
  1. A. Soriano1,2,
  2. G. Pazzola2,
  3. L. Boiardi2,
  4. F. Muratore2,
  5. P. Macchioni2,
  6. R. Aldigeri3,
  7. M. Casali4,
  8. A. Versari4,
  9. C. Salvarani2,5
  1. 1Campus Bio-Medico University, Rome
  2. 2Department of Internal Medicine, Rheumatology Unit, Arcispedale Santa Maria Nuova - IRCCS, Reggio Emilia
  3. 3Department of Clinical and Experimental Medicine, University of Parma, Parma
  4. 4Nuclear Medicine Unit, Arcispedale Santa Maria Nuova - IRCCS, Reggio Emilia
  5. 5Modena and Reggio Emilia University, Modena, Italy


Background The interpretation of data from 18F-FDG PET/CT studies on large vessel vasculitis (LVV) is difficult due to the scarcity of studies and to the heterogeneity of LVV populations examined. In the absence of gold standard parameters for the assessment of LVV arterial inflammation, there is a great need to develop analytical methodologies useful to properly exploit the information derived from such studies. Principal component analysis (PCA) and cluster analysis (CA) have not yet been applied to explore the LVV distribution patterns, assessed by 18F-FDG PET/CT.

Objectives The aim of our study was to investigate whether PCA and CA are useful methods in identifying distinct distribution patterns of LVV, according to the specific diagnostic entity examined (giant cell arteritis, GCA; Takayasu's arteritis, TAK).

Methods A total of 130 18F-FDG PET/CT studies have been retrospectively examined by a nuclear physician blinded to clinical data. Maximum standardized uptake values (SUVmax) in 14 vascular districts including aortic segments (ascending aorta, thoracic aorta, aortic arch, discending thoracic aorta and abdominal aorta) and the main tributaries (carotid, subclavian, axillary, iliac and femoral arteries) have been measured and transformed into Z-scores. Identification of distribution patterns of vascular involvement has been performed using PCA and agglomerative hierarchical CA (SPSS Statistics, version 22nd).

Results Three groups of vascular districts with similar trends in terms of standardized SUVmax have been identified: epiaortic arteries; aortic arch and ascending aorta; descending and abdominal aorta, with iliac and femoral arteries. A component including the entire aortic district was identified in TAK group, but not in GCA group.

Conclusions PCA and CA approach revealed a subtle skewing in terms of distribution patterns of arterial involvement between TAK and GCA, assessed by 18F-FDG PET/CT SUVmax values. The influence of atherosclerosis and immunosenescence on the different trends in the aorta districts of TAK and GCA needs to be further elucidated.

  1. Grayson PC, et al. Distribution of arterial lesions in Takayasu's arteritis and giant cell arteritis. Ann Rheum Dis 2012;71:1329–1334.

  2. Arnaud L, et al. Cluster analysis of arterial involvement in Takayasu arteritis reveals symmetric extension of the lesions in paired arterial beds. Arthritis Rheum 2011;63:1136–40.

Disclosure of Interest None declared

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