Intracoronary Imaging
There are various intracoronary imaging methods available and the imaging will help operators to visualize coronary arterial wall.
Intravascular ultrasound (IVUS)
Two types of IVUS systems are available.
- Phased Array: use multiple transducer elements permanently mounted along the circumference of the catheter tip
- Mechanical: utilizes single transducer mounted at the tip, which quickly rotates to visualize the entire vessel in cross-section
Indications of IVUS
- To determine lumen area, lesion complexity (e.g., plaque burden, calcification), and lesion length, especially in bifurcations lesions
- To access the severity of angiographically intermediate left main disease
- To analyze stent apposition, lesion coverage, and edge dissection post stent deployment
- To investigate coronary vasculopathy in transplanted hearts
Optical Coherence Tomography (OCT)
OCT technology utilizes backscattering (reflection) of light (in the 1300 nm range) wavelength to obtain cross-sectional images of coronary artery and has a 10-fold higher image resolution than IVUS). This allows imaging of the coronary artery in great detail and potentially providing unique insights into coronary artery pathophysiology.
Two Methods are Used:
- Time domain OCT — is used in first generation OCT. Due to its relatively slow data acquisition and the need for an occlusion balloon to remove the blood from vessels, its use is limited.
- Fourier domain OCT — Since 2008, a new generation of OCT systems (also called Fourier domain OCT systems) have been available for widespread clinical use. The data acquisition speed in Fourier-domain OCT is much faster than time-domain OCT system.
Indications of OCT
- Assessment of plaque morphology (e.g., plaque erosion in ACS)
- Analyze stent apposition, lesion coverage, and edge dissection
- Evaluate for adequate stent expansion, especially in cases of in-stent restenosis and stent thrombosis
Near-infrared Spectroscopy (NIRS)
- NIRS and IVUS could determine lipid core-containing plaques (LCPs) by using near-infrared region of the electromagnetic spectrum (from 780 nm to 2500 nm)
- In contrast to OCT, NIRS can image through blood, as it does not need light to be directly reflected back to the detector
- Although utility of NIRS is mainly used in clinical trial, its use in daily clinical practice remains limited