Expert review document part 2: methodology, terminology and clinical applications of optical coherence tomography for the assessment of interventional procedures

This document is complementary to an Expert Review Document on Optical Coherence Tomography (OCT) for the study of coronary arteries and atherosclerosis.1 The goal of this companion manuscript is to provide a practical guide framework for the appropriate use and reporting of the novel frequency domain (FD) OCT imaging to guide interventional procedures, with a particular interest on the comparison with intravascular ultrasound (IVUS).1–4 In the OCT Expert Review Document on Atherosclerosis, a comprehensive description of the physical principles for OCT imaging and time domain (TD) catheters (St Jude Medical, Westford, MA, USA) was provided.1 The main advantage of FD-OCT is that the technology enables rapid imaging of the coronary artery, using a non-occlusive acquisition modality. The FD-OCT catheter (DragonflyTM; St Jude Medical) employs a single-mode optical fibre, enclosed in a hollow metal torque wire that rotates at a speed of 100 r.p.s. It is compatible with a conventional 0.014″ angioplasty guide wire, inserted into a short monorail lumen at the tip. The frequency domain optical coherence tomography lateral resolution is improved in comparison with TD-OCT, while the axial resolution did not change. These features, together with reduced motion artefacts and an increased maximum field of view up to 11 mm, have significantly improved both the quality and ease of use of OCT in the catheterization laboratory.3,4 However, the imaging depth of the FD-OCT is still limited to 0.5–2.0 mm.5 The main obstacle to the adoption of TD-OCT imaging in clinical practice is that OCT cannot image through a blood field, and therefore requires clearing or flushing of blood from the lumen.1 The 6 Fr compatible DragonflyTM FD-OCT catheter is so far the only one in the market, as two other systems from Volcano and Terumo, which …