Parametric ultrasound imaging using the cumulative extrema of the log-normal scale parameter can accurately detect high intensity focused ultrasound-induced thermal lesions (ROC AUC 0.89) and action potential amplitude reduction.
Does parametric ultrasound imaging detect thermal lesions and action potential changes during HIFU ablation in perfused canine cardiac wedge preparations?
Parametric ultrasound imaging using cumulative extrema of the log-normal parameter σ can accurately detect thermal lesions and action potential amplitude reductions during HIFU ablation in a canine wedge model.
Effect estimate: ROC AUC 0.89
Intra-procedural imaging is important for guiding cardiac arrhythmia ablation. It is difficult to obtain intra-procedural correlation of thermal lesion formation with action potential (AP) changes in the transmural plane during ablation. This study tested parametric ultrasound imaging for transmural imaging of lesion and AP changes in high intensity focused ultrasound (HIFU) ablation using coronary perfused canine ventricular wedge preparations (n = 13). The preparations were paced from epi/endocardial surfaces and subjected to HIFU application (3.5 MHz, 11 Hz pulse-repetition-frequency, 70% duty cycle, duration 4 s, 3500 W/cm(2)), during which simultaneous optical mapping (1 kframes/s) using di-4-ANEPPS and ultrasound imaging (30 MHz) of the same transmural surface of the wedge were performed. Spatiotemporally correlated AP measurements and ultrasound imaging allowed quantification of the reduction of AP amplitude (APA), shortening of AP duration at 50% repolarization, AP triangulation, decrease of optical AP rise, and change of conduction velocity along tissue depth direction within and surrounding HIFU lesions. The threshold of irreversible change in APA correlating to lesions was determined to be 43 ± 1% with a receiver operating characteristic (ROC) area under curve (AUC) of 0.96 ± 0.01 (n = 13). Ultrasound imaging parameters such as integrated backscatter, Rayleigh (α) and log-normal (σ) parameters, cumulative extrema of σ were tested, with the cumulative extrema of σ performing the best in detecting lesion (ROC AUC 0.89 ± 0.01, n = 13) and change of APA (ROC AUC 0.79 ± 0.03, n = 13). In conclusion, characteristic tissue and AP changes in HIFU ablation were identified and spatiotemporally correlated using optical mapping and ultrasound imaging. Parametric ultrasound imaging using cumulative extrema of σ can detect HIFU lesion and APA reduction.
Wu et al. (2013) studied Cardiac arrhythmia ablation (animal model) (n=13). High intensity focused ultrasound (HIFU) ablation vs. Pre-ablation baseline / non-lesion tissue was evaluated on Detection of HIFU lesion using cumulative extrema of log-normal parameter (Δσ)max (ROC AUC 0.89). Parametric ultrasound imaging using the cumulative extrema of the log-normal scale parameter can accurately detect high intensity focused ultrasound-induced thermal lesions (ROC AUC 0.89) and action potential amplitude reduction.