Image-Based Frame Gating of IVUS Pullbacks: A Surrogate for ECG
Intravascular ultrasound (IVUS) is a catheter-based modality which is used to produce high-resolution, cross-sectional images of the interior of blood vessels. By capturing 2-D IVUS images continually while translating the catheter, a volumetric image of a vessel may be digitally reconstructed. To improve the quality of these volumes, electrocardiogram (ECG)-based frame gating is often applied to alleviate motion artifacts caused by the beating heart. However, there are several issues surrounding the use of ECG signals which make their use for this purpose potentially suboptimal. We introduce a method which gates pullback sequences by examining the imaging data alone, without requiring synchronous ECG, and guarantees that frames will be collected at those points in time when the heart is maximally motionless (i.e., regardless of the fraction of cardiac phase associated with those points). We compare the results of our method and of ECG on pullbacks captured in vivo in swine.