Inter-reader agreement of 18F-FDG PET/CT for the quantification of carotid artery plaque inflammation

Kjersti Johnsrud; Therese Seierstad; David Russell; Mona-Elisabeth Revheim

doi:10.1177/2048004020980941

Inter-reader agreement of ¹⁸F-FDG PET/CT for the quantification of carotid artery plaque inflammation

JRSM Cardiovasc Dis. 2020 Dec 15:9:2048004020980941. doi: 10.1177/2048004020980941. eCollection 2020 Jan-Dec.

Authors

Kjersti Johnsrud^{1

2}, Therese Seierstad³, David Russell^{2

4}, Mona-Elisabeth Revheim^{1

2}

Affiliations

¹ Department of Nuclear Medicine, Division of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway.
² Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
³ Department for Research and Development, Division of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway.
⁴ Department of Neurology, Oslo University Hospital, Oslo, Norway.

Abstract

Introduction: A significant proportion of ischemic strokes are caused by emboli from unstable atherosclerotic carotid artery plaques. Inflammation is a key feature of plaque instability. Positron emission tomography/computed tomography (PET/CT) with 2-deoxy-2-(¹⁸F)-fluoro-D-glucose (¹⁸F-FDG) is a promising technique to quantify plaque inflammation, but a consensus on the methodology has not been established. High inter-reader agreement is essential if ¹⁸F-FDG PET/CT is to be used as a clinical tool for the assessment of unstable plaques and stroke risk.

Methods: We assessed the inter-reader variability of different methods for quantification of ¹⁸F-FDG uptake in 43 patients with carotid artery stenosis ≥70%. Two independent readers delineated the plaque and collected maximum standardized uptake value (SUV_max) from all axial PET slices containing the atherosclerotic plaque.

Results: Uptake values with and without background correction were calculated and intraclass correlation coefficients were highest for uncorrected uptake values (0.97-0.98) followed by those background corrected by subtraction (0.89-0.94) and lowest for those background corrected by division (0.74-0.79).

Conclusion: Quantification methods without background correction have the highest inter-reader agreement for ¹⁸F-FDG PET of carotid artery plaque inflammation. The use of the single highest uptake value (max SUV_max) from the plaque will facilitate the method's clinical utility in stroke prevention.

Keywords: 18F-FDG PET/CT; cardiology; carotid stenosis; imaging of the brain and arteries; primary and secondary stroke prevention; quantification method; stroke.