Image-Based Real-Time Motion Gating of 3D Cardiac Ultrasound Images

Cardiac phase determination of 3D ultrasound (US) imaging has numerous applications including intraand inter-modality registration of US volumes, and gating of live images. We have developed a novel and potentially clinically useful real-time three-dimensional (3D) cardiac motion gating technique that facilitates and supports 3D USguided procedures. 0ur proposed real-time 3D-Masked-PCA technique uses the Principal Component Analysis (PCA) statistical method in combination with other image processing operations. Unlike many previously proposed gating techniques that are either retrospective and hence cannot be applied on live data, or can only gate respiratory motion, the technique is able to extract the phase of live 3D cardiac US data. It is also robust to varying image-content; thus it does not require specific structures to be visible in the US image. We demonstrate the application of the technique for the purposes of real-time 3D cardiac gating of trans-oesophageal US used in electrophysiology (EP) and trans-catheter aortic valve implantation (TAVI) procedures. The algorithm was validated using 2 EP and 8 TAVI clinical sequences (623 frames in total), from patients who underwent left atrial ablation and aortic valve replacement, respectively. The technique successfully located all of the 69 end-systolic and end-diastolic gating points in these sequences.