Feature Of The Week 6/30/13: Ultrafast Intravascular Optical Coherence Tomography Imaging
The fastest commercial intravascular optical coherence tomography (OCT) systems acquire 160 frames/second with 500 lines/frame, and the pullback speed is limited to 40 mm∕s. In this situation, the images are under sampled in the pullback direction: Only 12% of the lumen is sampled because the sampling interval of 250 μm is much larger than the transverse resolution, which is approximately 30 μm. In clinical situations, the cardiac motion also affects the OCT acquisition. The pullback procedure for the whole artery takes several seconds. The cardiac motion during acquisition will cause inaccuracy in frame spacing and possibly frame order, due to motion of the catheter along the vessel. This can affect the fidelity of the longitudinal rendering and 3D visualization of the data. We propose to solve these issues by further increasing the speed of intravascular OCT.
We demonstrate intravascular OCT imaging with frame rate up to 3.2 kHz (192,000 rpm scanning). This was achieved by using a custom-built catheter in which the circumferential scanning was actuated by a 1.0 mm diameter synchronous motor. The OCT system, with an imaging depth of 3.7 mm (in air), is based on a Fourier domain mode locked laser operating at an A-line rate of 1.6 MHz. The diameter of the catheter is 1.1 mm at the tip. Ex vivo images of human coronary artery (78.4 mm length) were acquired at a pullback speed of 100 mm/s. True 3D volumetric imaging of the entire artery, with dense and isotropic sampling in all dimensions, was performed in <1 second acquisition time.
The ultrafast intravascular OCT scanner we demonstrate in this study allows the acquisition of a fully sampled 3D data set of a coronary artery in less than a second. The shorter procedure will eliminate cardiac motion artifacts and further reduce the amount of flush media needed for imaging. It also significantly improves the longitudinal rendering of the pullback, a display mode that is widely used in clinical practice.
For more information see recent Article. Courtesy of Gijs van Soest from Erasmus Medical Center and Robert Huber from Ludwig Maximilians Universität München.