Meeting Abstract
Diffusible iodine-based contrast-enhanced computed tomography (diceCT) facilitates three-dimensional imaging of soft-tissue anatomy at high spatial resolutions, relatively rapidly, and at manageable expense. A critical preparatory step is identifying the length of time for which a specimen should stain in iodine potassium-iodide (I2KI) to (1) ensure the contrast agent fully penetrates the deepest tissues, but (2) without over-staining the sample thus reducing inter-tissue contrast differences and/or contributing to soft-tissue distortions. Finding this balance includes accounting for confounding factors such as size and iodine concentration. Here we designed a 780-sample repeated-measures analysis, using pairwise grayscale differentials to systematically document and analyze the effects of these variables. We used thick (~10 mm) sections from the bodies of adult specimens of pythons (Liasis, Antaresia) to represent standard samples of vertebrate tissues (e.g., cortical bone, spinal gray and white matter, skeletal muscle). Four size classes based on section diameter (~10, 20, 30, and 40 mm) were prepared in triplicate. Triplicates were stained with a series of exposures to I2KI (1, 3, 5, and 10% concentrations) and at specific durations (7, 14, 21, 28, and 35 days), followed by μCT scanning to measure tissue grayscale values and total depth of staining within sections. Based on staining completeness and tissue differentiation, we generally found that longer staining durations produce the best results. However, acceptable contrasts can certainly be achieved using shorter staining periods at higher concentrations. We summarize the scope of our findings into best-practices recommendations for the diceCT community.
