Fig. 1. Number of PCI cases and its growth rate in China in the past decade (the data was plotted according to the annual report from CCIF2011 to CCIF2019). (a) Number of PCI cases in China in the past decade; (b) growth rate of PCI cases in China in the past decade

Fig. 2. Structural diagrams of three generations of OCT systems. (a) Time domain OCT; (b) spectral domain OCT; (c) swept source OCT

Fig. 3. Number of publications about OCT applied to fields of ophthalmology, cardiology, dermatology, and gastroenterology in 1991—2019 (the data was obtained from annual PubMed publications)

Fig. 4. Number of publications about OCT endoscopic imaging applied to fields of cardiovascular, esophagus, respiratory tract, and gastrointestinal tract in 1995—2019 (the data was obtained from annual PubMed publications)

Fig. 5. Schematics of OCT scanning probe design for different endoscopes^[30]. (a) Side-viewing endoscopic OCT scanning probe; (b) forward-viewing endoscopic OCT scanning probe; (c) proximal scanning fiber rotating probe; (d) distal-scanning endoscope with micromotor

Fig. 6. Schematic of the first single mode fiber based endoscopic catheter^[26]. (a) Optical rotatory connector; (b) distal end of catheter

Fig. 7. Commercial OCT imaging catheter

Fig. 8. Representative commercial intravascular OCT products of different types

Fig. 9. OCT images of normal coronary vessels and representative plaque and coronary microstructures

Fig. 10. Representative OCT images for stent evaluation. (a) Stent malapposition; (b) in-stent restenosis; (c) stent thrombosis