Label-free volumetric imaging of porcine kidney tissue over extended areas using dynamic MHz-OCT.

Dynamic optical coherence tomography (dOCT) enables high-resolution, label-free 3D tissue imaging with functional contrast, offering a potential advancement in kidney transplant viability assessment. Currently, no widely accepted non-invasive method provides an objective evaluation of transplant viability, as conventional imaging lacks the resolution to assess microvascular integrity and cellular dynamics. However, the clinical use of available dOCT systems is limited by prolonged imaging times that hinder clear visualization of tissue dynamics. To address these challenges, this paper presents a swept-source 3.2 MHz-OCT system for dynamic, high-speed, extended-area imaging. The system integrates an optimized inter-volume scan protocol and a micrometer-precision linear robot, enabling extended‑scale tissue imaging over an area of about 2.6 × 2.6 mm. Using freshly excised porcine kidney tissue, we demonstrate recent advancements and challenges in MHz-dOCT for kidney imaging. Identified anatomical features are thoroughly examined, compared across resolutions, and validated through histology to assess the system's clinical potential.