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Optical Coherence Tomography (OCT) and Intravascular Ultrasound (IVUS)
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What is Optical Coherence Tomography (OCT) and Intravascular Ultrasound (IVUS)?

Optical Coherence Tomography (OCT) and Intravascular Ultrasound (IVUS) are specialised imaging techniques that help cardiologists see inside the coronary arteries with much greater detail than standard angiography. These technologies are often used during angioplasty procedures when doctors need a clearer understanding of the artery’s condition before, during, or after treatment.
OCT uses light waves to produce highly detailed images of the inner layers of the blood vessel. Because of its exceptional image resolution, it can help identify plaque characteristics, small tears in the artery wall, blood clots, and the extent of stent expansion after placement.
IVUS, on the other hand, uses ultrasound waves to create cross-sectional images from inside the artery. It allows cardiologists to assess the overall size of the vessel, measure the extent of plaque build-up, and evaluate calcium deposits that may affect treatment decisions.
During the procedure, a thin imaging catheter is guided through the blood vessels to the coronary arteries. The images obtained provide valuable information that helps the cardiologist choose the most appropriate treatment approach and ensure that stents are positioned and expanded correctly.
These advanced imaging tools are particularly useful in patients with complex coronary artery disease, heavily calcified arteries, left main coronary artery disease, or cases where conventional angiography does not provide sufficient information. By offering a more accurate view of the arteries, OCT and IVUS help improve treatment precision and support better long-term outcomes

Types of Optical Coherence Tomography (OCT) and Intravascular Ultrasound (IVUS):

Both OCT and IVUS have evolved significantly over the years, with newer technologies providing faster image acquisition and greater diagnostic accuracy. Depending on the clinical requirement, cardiologists may use different forms of these imaging techniques to better understand the condition of the coronary arteries and guide treatment decisions.

Types of Optical Coherence Tomography (OCT)

• Time-Domain OCT (TD-OCT): Time-Domain OCT was one of the earliest forms of OCT used in cardiology. It generated detailed images of blood vessels by measuring the delay of reflected light. While it played an important role in the development of intravascular imaging, its use has become limited with the introduction of more advanced systems.
• Frequency-Domain OCT (FD-OCT): Frequency-Domain OCT, also known as Optical Frequency Domain Imaging (OFDI), is the technology most commonly used today. It captures high-resolution images much more quickly than earlier systems, allowing cardiologists to assess plaque characteristics, vessel structure, and stent placement efficiently during coronary interventions.

Types of Intravascular Ultrasound (IVUS)

• Mechanical IVUS: Mechanical IVUS uses a small rotating ultrasound transducer positioned at the catheter tip. As the device rotates, it creates detailed cross-sectional images of the artery, helping physicians evaluate vessel dimensions and the extent of plaque build-up.
  Solid-State IVUS:
  In this system, multiple ultrasound sensors are built into the catheter rather than relying on a rotating component. This design enables rapid, reliable image acquisition while providing valuable information about the vessel wall and lesion characteristics.
• Virtual Histology IVUS (VH-IVUS): Virtual Histology IVUS is an advanced imaging technique that analyses ultrasound data to provide insights into the composition of arterial plaque. It can help distinguish between different plaque types, including fibrous tissue, fatty deposits, and calcified areas, which may influence treatment planning.
• Integrated Backscatter IVUS (IB-IVUS): Integrated Backscatter IVUS uses specialised software to analyse reflected ultrasound signals and provide additional information about plaque structure. This can assist cardiologists in understanding the nature of coronary blockages and selecting the most appropriate intervention strategy.

The choice of imaging technique depends on the patient’s condition and the information needed during the procedure. OCT is often selected when detailed visualisation of the inner vessel surface or stent placement is required, whereas IVUS is particularly useful for assessing larger vessels, deeper arterial structures, and heavily calcified lesions. Together, these technologies help improve the accuracy of coronary interventions and support better clinical outcomes.