An in-depth comparison of vascular inflammation on ultrasound, FDG-PET/CT and MRI in patients with suspected giant cell arteritis

Abstract

Background

Giant cell arteritis (GCA) is a difficult to diagnose large vessel vasculitis. CDUS, FDG-PET/CT and MRI are increasingly used for GCA diagnosis. This study aims to assess vascular wall lesions in GCA suspected patients, directly comparing CDUS, FDG-PET/CT and MRI with each other.

Methods

In a nested-case control study, consecutive GCA suspected patients were included. Scans were retrospectively assessed by two experts per imaging modality. Inter- and intraobserver agreement using Cohen’s or Fleiss Kappa were calculated to assess agreement between experts, a few duplicated scans and between imaging modalities. Sensitivity and specificity of the imaging modalities for overall diagnostic performance and for individual arteries were calculated.

Results

In total, 42 patients were included. Overall diagnostic performance of imaging modalities was comparable. Sensitivity and specificity were highest in the temporal artery for CDUS (76% and 93%; Kappa > 0.7) and MRI (60% and 100%; Kappa > 0.7), and in the vertebral (61% and 100%; Kappa 0.56) and maxillary artery (52% and 100%; Kappa 0.75) for FDG-PET/CT. Agreement between all modalities for a positive temporal artery was 0.76, but only 0.28 between CDUS and FDG-PET/CT. Agreement for the axillary artery was 0.7 between CDUS and FDG-PET/CT.

Conclusion

The temporal artery can be assessed by CDUS and MRI with good sensitivity and high specificity, and the axillary artery by CDUS and FDG-PET/CT with high agreement between the two modalities. In addition, the vertebral and maxillary artery can be assessed by FDG-PET/CT with good sensitivity and specificity, however the vertebral artery had moderate interobserver agreement.