Table 1. Technical characteristics and differences of intra-coronary imaging modalities.

Characteristics	Grey-scale IVUS	FD-OCT	VH-IVUS	NIRS
Frequency (MHz)	20–45	N/A	20–45	N/A
Axial resolution (um)	100–200	15–20	200	N/A
Tissue penetration (mm)	>5	1–2.5	>5	1–2
Pullback speed (mm/sec)	0.5–1	20–40	0.5–1	0.5
Frame rate (frames/sec)	10–30	100–160	10–30	N/A
Image through blood	Yes	No	Yes	Yes