Table V.

Advantages and disadvantages of several methods for evaluating vulnerable plaques (14-15).

Modality	Advantages	Disadvantages
CAG	The method of CAG is simple, it requires a short time, has fewer complications and high diagnostic value. To a certain extent, the smoothness and stenosis of the lumen may be observed	The effect of foreshortening leads to underestimation of the length of the stenosis of the lesion and there are large errors in the measurement of the vascular structure at the bifurcation and the eccentric plaque, and it is impossible to clearly determine whether the plaque is a vulnerable plaque
Angioscopy	The surface of the thrombus and plaque may be directly observed and the fibrous cap rupture and thrombosis may be detected. At the same time, the color of the plaque may be observed (white indicates mostly a stable plaque and yellow mostly a vulnerable plaque)	The size of the device is large. It may only be used to observe limited blood vessels and is not able to observe the inside of the plaque and the blood vessel wall. In addition, the blood flow requires to be blocked, which may cause remote ischemia
IVUS	It is able to clearly distinguish the structure of each layer of the blood vessel wall, determine the diameter of the lumen, plaque volume, load and vascular remodeling, and may distinguish the properties of plaque such as lipid core, calcification and fibrous tissue	IVUS may only display image information of plaque subcomponents and not able to provide any quantitative detection. Only the calcified surface structure may be observed and the display effect is not optimal
	With strong penetrating power, it may provide overall and comprehensive imaging information for plaque assessment	The thickness of the fiber cap cannot be accurately determined and the detection of thrombus is not sufficiently sensitive
OCT	It has a high resolution, may accurately evaluate the microstructure close to the lumen, particularly in the unstable components of plaque, such as the thickness of the fiber cap, macrophage infiltration, lipid plaque size or plaque rupture. The fibrous cap thickness measurement is in good agreement with histology	The penetration ability is weak (1-2 mm) and its penetration depth is far less than that of IVUS (8-10 mm). OCT is not able to provide an accurate analysis of the full picture of the lesion. The lesion area covered by the thrombus may not be used for an accurate assessment

OCT, optical coherence tomography; CAG, coronary angiography; IVUS, intravascular ultrasound.