Table 1. Features of intravascular imaging modalities.

Features	Grayscale IVUS	VH-IVUS	OCT	NIRS	Angioscopy
Axial resolution	150 ìm	200 ìm	10-20 ìm	N/A	<150 ìm
Studies regarding the prediction of cardiovascular events	Echolucent plaque is at risk for ACS (75) Higher plaque burden is associated with MACE (76)	Minimal lumen area of <4 mm2, plaque burden >70% and VH-derived TCFA predicts ACS (77) VH-derived TCFA predicts MACE (78)	No available evidence exists	Lipid core burden index (LCBI) >43.0 is at risk of MACE (79)	Yellow plaques predict ACS (70) Number of yellow plaques predicts ACS (80) In-stent yellow plaque is at risk of MACE (81)
Advantages	Precise tomographic measurement of lumen area, plaque size and distribution	Ability to differentiate plaque composition	Excellent axial resolution Ability to assess fibrous cap thickness and macrophage filtration	High sensitivity and specificity in the detection of lipid rich plaque	Direct visualization of plaque color and morphology of coronary surface
Disadvantages	Limited axial resolution Inaccuracy in the assessment of plaque composition	Limited axial resolution Inability in the assessment of plaque composition behind calcium	Low tissue penetration Need of contrast medium flush for image acquisition	Lack of prospective data	Need of continuous injection of saline during image acquisition Limited ability to penetrate beyond the coronary surface

IVUS, intravascular ultrasound; VH-IVUS, virtual histology intravascular ultrasound; OCT, optical coherence tomography; NIRS, near infrared spectroscopy; ACS, acute coronary syndrome; MACE, major cardiovascular events.