Up around the bend: progress and promise of intravascular imaging in neurointerventional surgery

Endovascular treatment in peripheral and coronary circulations has been greatly advanced with the aid of intravascular imaging such as optical coherence tomography (OCT) and intravascular ultrasound (IVUS).1 2 Studies have shown that these technologies have a clinical impact, such as reducing in-hospital adverse events and improving long-term survival following coronary artery stenting.3 For the intracranial circulation, however, translation and routine use of such intravascular imaging has lagged, owing to the unique tortuosity of the neurovasculature. Specifically, complexities around both miniaturization of the imaging probe with appropriate flexibility and a solution for distal rotational control (eg, replacement of the torque cable that experiences high friction within the catheter construct in tortuous vessels) are difficult to overcome. Major technological advancements in neurovascular devices have, on the other hand, been realized in recent years, such as the ability to braid wires on the scale of tens of microns (intrasaccular devices, flow diverters, etc); laser cutting of micron-sized features in nitinol devices; biomimetic surface modifications to reduce thrombogenicity of implants; and complex, multicomposite, large-bore catheters that can go further into the brain vasculature than ever imagined. Some of these developments have far exceeded the resolution of, or induce significant artifacts for, standard imaging modalities. The ability to directly image neurovascular implants with micron-size features, and the vascular response to these implants, is presently not available for the imaging of the intracranial circulation. Coming up around the bend, however, is the miniaturization of catheter-based imaging technologies capable of overcoming these obstacles. Already for some time, research into the neurovascular applications of intravascular imaging has been performed in cadavers4 5 and animal models6–10 to show the potential impact that it could have in neurointerventional surgery. As is now …