Aristeidis H. Katsanos, MD
Optical coherence tomography (OCT) uses low-coherence interferometry to produce two-dimensional images of optical scattering with promising clinical and research applications in the evaluation of vasculature in different regions and settings. Despite an imaging depth of only a few millimeters, OCT can produce significantly higher resolution images than ultrasound due to the inherent properties of light waves to provide higher quality transverse imaging compared to sonic waves.
OCT angiography has permitted the noninvasive evaluation of retinal vascular abnormalities with an unprecedented level of detail, on the micron level, which enables the evaluation of vascular pathologies in individual vessel wall layers. Extensive research applications on intravascular OCT imaging has also been performed in coronary arteries, focusing on vessel lumen geometry assessment, disease severity evaluation and treatment guidance of coronary artery stenting. OCT has recently been extensively used for the evaluation of extracranial vascular pathologies, including atherosclerosis, stent placement and dissection, reporting excellent interobserver and intraobserver agreement in the diagnoses of carotid artery thrombus, neovascularization, ulceration, and lipid pool.
In intracranial circulation, OCT is known to provide accurate and reproducible assessment of all vessel wall layers and origins of the perforating arteries, and thus could provide an additional invaluable imaging method for the diagnosis and management of patients with complex intracranial vascular pathology. Numerous publications have focused on the potential role of OCT in the risk stratification of intracranial aneurysm rupture, providing invaluable information on aneurysm vessel wall thickness and histopathologic characteristics. Moreover, high-resolution OCT imaging of the vessel wall structural composition may provide additional prognostic criteria for cerebral aneurysm management and post-embolization aneurysm healing, with the assessment of vascular changes that are not visible in conventional angiography.
Since endovascular treatment has become the standard of care for patients with acute ischemic stroke due to large vessel occlusion, the application of OCT could provide additional information in the evaluation of residual stenosis, plaque or thrombosis after mechanical thrombectomy. Focusing on stroke research, future studies should evaluate further the benefits and potential risks associated with the application of OCT in different clinical settings, while additional research is needed for the optimization of catheters that can be safely and easily navigated through the torturous anatomy of the distal cerebral vasculature.