Table 1:

Original American Heart Association (AHA) classification for atherosclerotic plaques, and modified classification adapted for CT

Type of PlaqueAHA Histologic Classification of Atherosclerotic PlaquesClassification of Atherosclerotic Plaques Adapted for CT
0No intimal thickeningNo intimal thickening
1Initial lesion; not grossly apparent plaque; foam cellsThin plaque with no calcification
2Fatty streak; lesion grossly apparent; foam cells and smooth muscle cells contain lipid droplets
3Preatheroma; foam cells contain lipid droplets and increased number of smooth muscle cells; raised fatty streakPlaque with small lipid cores and no calcification
4Atheroma; massive extracellular lipid pool (lipid core); grossly visible; infiltrated with foam cells and smooth muscle cellsPlaque with a large lipid core, covered by a fibrous cap, possible small calcifications
5aFibroatheroma; type IV with a fibrous cap
5bCalcified plaque; lesion with a lipid core or fibrotic tissue, with large calcificationsPlaque with a lipid core or fibrotic tissue, with large calcifications
5cFibrotic plaque: fibrous connective tissue, no lipid corePlaque with fibrous tissue, no lipid core, possible small calcifications
6bWide hemorrhageWide hemorrhage