Characterization of catheter motion in intracardiac echocardiography (ICE) elastography imaging
Momentum created by a high intensity acoustic wave emitted in intracardiac echocardiography (ICE) Acoustic Radiation Force Impulse (ARFI) imaging sequences is absorbed by the backing material of the catheter causing a kickback motion. This study was designed to characterize this motion. An elastography phantom was imaged with an 8Fr Soundstar™ ICE catheter and a 10Fr, 128 element ICE catheter with various fulcrum lengths and mechanical steering angles to assess the kickback motion. The fulcrum lengths (FLs) varied from 30 mm to 50 mm and showed irregularities in the motion in FLs over 40 mm in the 8Fr SoundStar™, but not in the 10Fr, 128 element ICE catheter. The mechanical steering, over the range tested in the 8Fr SoundStar™, did not have a statistically significant effect on the kickback motion. The motion was on the same order of magnitude of the induced displacements in both catheters. The kickback motion induces a bias of 0.5 to 3 μm to the ARFI images that is not consistent over the ARFI imaging ensemble. The current motion filtering techniques that are used to remove bulk cardiac or respiratory motion from the induced ARFI displacements are not sufficient for removing the kickback motion. In some cases, the motion filter increases the present bias. For both catheters, failure to properly account for this effect could degrade ICE ARFI image quality. New motion filtering techniques are necessary to reduce the kickback motion effect on induced displacements during ICE ARFI imaging.
