Original American Heart Association (AHA) classification for atherosclerotic plaques, and modified classification adapted for CT
| Type of Plaque | AHA Histologic Classification of Atherosclerotic Plaques | Classification of Atherosclerotic Plaques Adapted for CT |
|---|---|---|
| 0 | No intimal thickening | No intimal thickening |
| 1 | Initial lesion; not grossly apparent plaque; foam cells | Thin plaque with no calcification |
| 2 | Fatty streak; lesion grossly apparent; foam cells and smooth muscle cells contain lipid droplets | |
| 3 | Preatheroma; foam cells contain lipid droplets and increased number of smooth muscle cells; raised fatty streak | Plaque with small lipid cores and no calcification |
| 4 | Atheroma; massive extracellular lipid pool (lipid core); grossly visible; infiltrated with foam cells and smooth muscle cells | Plaque with a large lipid core, covered by a fibrous cap, possible small calcifications |
| 5a | Fibroatheroma; type IV with a fibrous cap | |
| 5b | Calcified plaque; lesion with a lipid core or fibrotic tissue, with large calcifications | Plaque with a lipid core or fibrotic tissue, with large calcifications |
| 5c | Fibrotic plaque: fibrous connective tissue, no lipid core | Plaque with fibrous tissue, no lipid core, possible small calcifications |
| 6a | Ulcerations | Ulcerations |
| 6b | Wide hemorrhage | Wide hemorrhage |
| 6c | Thrombosis | Thrombosis |