Comparison between Autofluorescence and Reflectance-Based Hyperspectral Imaging for Visualization of Atrial Ablation Lesions

Abstract

Rationale: Atrial fibrillation (AF) is the most common cardiac arrhythmia. A primary cause of AF is abnormal electrical activity stemming from ectopic foci located near muscle sleeves of the pulmonary veins. One of the most common and effective ways to treat AF is radiofrequency ablation (RFA) to electrically isolate the pulmonary veins from the left atrium or to directly eliminate ectopic foci. Because endocardial surface of left atrium is covered by thick interwoven layers of collagen and elastin, sites of RF ablation are hard to see.Hypothesis: We hypothesized that RFA-induced muscle damage in the left atrium can be visualized by implementing two different modalities of Hyperspectral Imaging (HSI) technology. HSI captures the entire spectrum for each pixel in an image. Post-acquisition analysis is used to reveal the main spectral components present in the sample to spatially separate regions in the image based on their spectra.Methods: Ablations were performed on a freshly excised porcine left atrial tissue. Images were acquired between 420-720 nm at a spatial resolution of 1392x1040 pixels, using a commercial HSI system (Nuance FX, PerkinElmer) fitted with a low magnification lens. UV LED (365nm) was used to illuminate samples for autofluorescence HSI datasets, while white light source was used for reflectance-based HSI experiments. Nonlinear unmixing was used to reveal the main spectral components and identify lesions sites.Results: Both HSI modalities greatly enhanced RF lesion visualization. The side by side comparison included: i) signal-to-noise ratio of the lesion component intensity profiles, ii) the optimum acquisition ranges and iii) the minimum number of wavelengths needed to differentiate between ablated and unablated tissue.Conclusion: The data provide technical basis for developing HSI catheter aiding real-time RFA lesion visualization during surgical ablation of AF.