Table 1.

Classification of plaque components on HR MRI

Plaque feature	Signal characteristics	Classification
Intraplaque hemorrhage (Altaf et al. 2007b, 2008)	Bright T1 signal (precontrast)	IPH present: ≥150% of T1 signal of adjacent muscle or pons
		IPH absent: T1 signal is < 150% of adjacent muscle or pons
Fibrous cap (Trivedi et al. 2004a,b)	Band of T2 high signal adjacent to lumen OR Enhancement of plaque on T1 (postcontrast)	Thick cap: the cap can be visualized and measured on T2. Thin or ruptured cap: no cap visualized with smooth or rough surface of plaque on T2 OR a clear defect or ulceration within the fibrous cap on T2 OR enhancement of plaque on T1 (postcontrast)
Lipid Core (Trivedi et al. 2004a,b; Saam et al. 2005)	Iso‐ to hyperintense on T1 (precontrast) Hypointense to isointense on T2	Area of T1 signal (precontrast) identified as lipid core is manually traced and area calculated. Lipid core % area = area of lipid core ÷ plaque area Plaque area = area of entire vessel – area of lumen Lipid Core Score: 0 = no lipid core identified 1 = lipid core area < 25% 2 = lipid core area >25%