Quantitative Ultrasound Analysis of Surgical Sites in Cardiac Surgery using Intracardiac Echocardiography

This study investigates the feasibility of using quantitative ultrasound (qUS) with intracardiac echocardiography (ICE) to evaluate radiofrequency (RF) ablation lesions. A key challenge in ICE-guided procedures is characterizing subsurface tissue change in the presence of acoustic/electrical interference from surgical hardware. To address this, we employ an entropy-based backscatter analysis—Dynamic Differential Entropy (DDE)—which computes Shannon entropy over temporally evolving ultrafast ensembles to capture microstructural and temporal scattering changes while mitigating non-physiological noise and motion artifacts. We validate DDE using (i) simulations that emulate ablation by varying scatterer size over time and (ii) ex-vivo porcine hearts (nine lesions) imaged before, during, and after ablation. In simulation, DDE monotonically tracked the imposed scatterer-size differences, unlike conventional ultrasound B-mode. In ex-vivo data, DDE localized the ablated region and DDE-derived lesion areas qualitatively agreed with optical planimetry on sliced tissue. Preliminary results support DDE as a promising, noise-tolerant qUS marker for intraoperative monitoring of cardiac ablation, motivating head-to-head comparisons with envelope-distribution qUS methods and future in-vivo studies.