Effect of concentration and staining duration of iodine contrast applied to study the masticatory muscle of Wistar rats in micro‐CT images

Abstract

The challenge to study the anatomy of the muscular system is to replace destructive methods such as macroscopic dissection with non‐destructive methods involving magnetic resonance imaging and computed microtomography (micro‐CT). The aim of this study was to evaluate the effect of concentration and staining duration of iodine contrast applied to study the masticatory muscle of Wistar rats in micro‐CT images. Fifteen male Wistar rats (Rattus norvegicus albinus), 2 months old (200–250g) from CEMIB‐UNICAMP were used. After euthanasia, the animals were randomly assigned to the experiments in 3 groups of 5 rats each, with the iodine contrast solutions of 3%, 5% and 10%. Each group was subdivided into 3 subgroups according to the staining duration: 7 days, 15 days and 30 days. The pieces were scanned on a 1174 Skyscan microtomograph (Bruker, Belgium) with a voltage of 50 Kv and amperage of 800 μA at the Piracicaba Dental School‐UNICAMP. The scanning of the pieces was done with a pixel dimension equal to 31 μm. After scanning, the images were exported to the software NRecon Reconstruction (Bruker, Belgium) in which they were reconstructed three‐dimensionally in axial sections presenting the x‐ray attenuation coefficients with values relative to the muscle structure reinforced by contrast. The reconstructed images were exported to the software Materialise MIMICS v18 (Materialise, Belgium) to evaluate the anatomical characteristics as well as the density of masticatory muscles. The muscles observed were: Temporal, Masseter (superficial part), Masseter (deep part), External pterygoid, Internal pterygoid and Zigomaticomandibular. These parameters were evaluated in each piece to compare the effects of different contrast concentration and staining duration. The 5% concentration showed better characterization of muscle groups, regardless of the period. At 5%, the 30‐day period showed better definition of muscle fibers. The 3% concentration presented only muscle mass and its contours, but there was no definition in the image that could differentiate each muscle. In the group with a concentration of 10%, contrast enhancement was observed only on the muscular surfaces. Thus, the solution concentration was the most effective parameter to stain the muscle fibers. The preparation and application protocol of iodine‐based contrast solution was most effective at 5% concentration with 30 days action.Support or Funding InformationNational Council for Scientific and Technological Development (PIBIC/CNPq).