Iodine staining outperforms phosphotungstic acid in high-resolution micro-CT scanning of post-natal mice cardiac structures.

Abstract

Purpose: Micro-computed tomography (micro-CT) scan provides high-resolution three-dimensional images of mineralized tissues in small animal models. Contrast enhancement is essential to visualize non-mineralized tissues with micro-CT scan. We attempted to compare the two most common contrast agents to stain and image mouse cardiac structures. Approach: Ex-vivo micro-CT scan images of the mouse hearts were obtained following staining by potassium iodide or phosphotungstic acid (PTA). PTA-stained samples were imaged after various durations following staining (14days, 25days, 187days, and 780days), whereas iodine-stained samples were imaged after 72hours. We compared median staining intensity between PTA and iodine at 0.1-mm intervals from the edge using the Mann Whitney test with correction for multiple comparisons. Results: Sixty post-natal mice hearts were stained with either PTA or iodine and imaged using micro-CT scan. Iodine proved to be faster and more uniform in complete enhancement of cardiac tissue in as short as 72h, whereas PTA required a significantly longer time period to penetrate mouse cardiac structure ( ). Median staining intensity with iodine was strongly higher than that with PTA from 0.1- to 1.5-mm distance from the epicardial edge (2-tailed value or lower throughout). Conclusions: Iodine-stained soft tissue imaging by micro-CT scan provides a non-destructive, efficient, and accurate visualization tool for anatomical analysis of animal heart models of human cardiovascular conditions. Iodine is more efficient compared to PTA to achieve complete murine myocardial staining in a significantly shorter time period.