Label-free wide-field holographic imaging of porcine, sheep, and rabbit esophageal tissue samples subjected to laser-induced thermal damage

Assessing histological changes caused by laser-induced thermal damage in the esophagus is crucial for evaluating endoscopic photothermal therapies. Conventional staining-based methods are often time-consuming, destructive, and subject to processing variability. Digital holographic microscopy (DHM), however, offers a label-free, quantitative approach by simultaneously recovering amplitude and phase information. This allows measurement of optical path length variations related to tissue morphology, refractive index, and thickness changes without the need for external contrast agents. We present a wide-field, off-axis DHM framework for the comprehensive assessment of photothermal coagulation in ex vivo esophageal tissue sections from rabbit, sheep, and porcine models. Through automated surface scanning for numerical reconstruction and stitching, we generated large-area maps that display amplitude, phase, and fused holographic data. The quantitative phase images identified localized changes in optical path length that corresponded to areas of coagulation and thermally affected tissue layers. These findings showed a strong correlation with conventional hematoxylin and eosin (H&E) stained histology, while maintaining the integrity of the native, unstained tissue. These results demonstrate the potential of DHM as a rapid, stain-free virtual histology tool for monitoring laser-induced thermal esophageal therapies and enhancing gastroenterological diagnostics.