Durability assessment of hydrogel mountings for contrast-enhanced micro-CT

Differential performance of aqueous- and ethylic-Lugol's iodine stain to visualize anatomy in μCT-scanned vertebrates

Museum specimens are an increasingly important tool for studying global biodiversity. With the advent of diffusible iodine-based contrast-enhanced computed tomography (diceCT), researchers can now visualize an organism's internal soft tissue anatomy without the need for physical dissection or other highly destructive sampling methods. However, there are many considerations when deciding which method of staining to use for diceCT to produce the best gray-scale contrast for facilitating downstream anatomical analyses. The general lack of direct comparisons among staining methodologies can make it difficult for researchers to determine which approaches are most appropriate for their study. Here, we compare the performance of ethylic-Lugol's iodine solution with aqueous-Lugol's staining solution across several vertebrate orders to assess differential imaging outcomes. We found that ethylic-Lugol's is better for visualizing muscle attachment to bone but provides overall lower contrast between soft tissue types. Comparatively, aqueous-based Lugol's provides high-contrast imaging among soft tissue types, although bone is more difficult to discern. We conclude that the choice of staining methodology largely depends on the type of anatomical data the researcher wishes to collect, and we provide a decision-based framework for assessing which staining methodology (ethylic or aqueous) is most appropriate for desired imaging results.

Contrast-Enhanced Micro-CT Imaging of Murine Mandibles: A Multi-Method Approach for Simultaneous Hard and Soft Tissue Analysis

AIM

To develop and evaluate a novel multi-method micro-computed tomography (μCT) imaging protocol for enhanced visualization of both hard and soft tissues in murine mandibles, addressing the limitations of traditional imaging techniques in dental research.

MATERIALS AND METHODS

We employed a contrast-enhanced (CE) μCT imaging technique using Lugol's iodine as a contrast agent to visualize the intricate structures of murine mandibles. The protocol involved the combination of conventional μCT imaging as well as CE-μCT, including decalcification with EDTA, allowing for simultaneous assessment of hard and soft tissues. The method is compared with standard imaging modalities, and the ability to visualize detailed anatomical features is discussed.

RESULTS

The CE-μCT imaging technique provided superior visualization of murine mandibular structures, including dental pulp, periodontal ligaments and the surrounding soft tissues, along with conventional μCT imaging of alveolar bone and teeth. This method revealed detailed anatomical features with high specificity and contrast, surpassing traditional imaging approaches.

CONCLUSION

Our findings demonstrate the potential of CE-μCT imaging with Lugol's iodine as a powerful tool for dental research. This technique offers a comprehensive view of the murine mandible, facilitating advanced studies in tissue engineering, dental pathology and the development of dental materials.

Spatial and temporal evaluation of iodine uptake and radiodensity in meniscus tissue using contrast-enhanced micro-CT

Rationale and objective

The visualization of soft tissues, like the meniscus, through X-ray micro-computed tomography (micro-CT), requires the use of contrast agents (CAs). While other studies have investigated CA diffusion in fibrocartilagineous tissues, this work aimed to optimize iodine staining protocols for meniscal tissue that improve their visualization by micro-CT. Specific objectives included evaluating the diffusion of CAs within meniscal samples over time, assessing volume changes due to staining, and identifying the iodine ions absorbed by the tissue.

Materials and methods

Water-based and PBS-based Lugol solutions (KI3) were used to stain sheep and pig menisci for 24 days. Samples were scanned using micro-CT at different time points (0, 1, 4, 8, 12, 16, 20, and 24 days) to monitor CA diffusion and volume changes. Micro-CT provided three-dimensional (3D) visualization of iodine distribution and quantification of volume changes and radiodensity in the menisci. Additionally, UV-visible spectroscopy (UV-vis) analyses were performed to determine the uptake of iodine ions by the meniscus.

Results

Results indicated volumetric shrinkage and increased radiodensity within the first days of staining, with diffusion primarily occurring from the periphery of the meniscus. UV-visible spectroscopy identified two iodide ions in the CA solution (I- and I3 -) and revealed a preferential absorption of the triiodide ion (I3 -).

Conclusion

This study demonstrated the utility of iodine-based CAs and micro-CT technique for visualizing and investigating the spatial and temporal iodine diffusion within the meniscal tissue of sheep and pigs. The findings of this study have important implications for using iodine-based CAs in imaging analyses of the meniscus and offer potentially valuable insights into the diffusion patterns of iodine in fibrocartilagineous tissues.

Contrast-enhanced Micro-CT 3D visualization of cell distribution in hydrated human cornea

Background

The cornea, a vital component of the human eye, plays a crucial role in maintaining visual clarity. Understanding its ultrastructural organization and cell distribution is fundamental for elucidating corneal physiology and pathology. This study comprehensively examines the microarchitecture of the hydrated human cornea using contrast-enhanced micro-computed tomography (micro-CT).

Method

Fresh human corneal specimens were carefully prepared and hydrated to mimic their in vivo state. Contrast enhancement with Lugol's iodine-enabled high-resolution Micro-CT imaging. The cells' three-dimensional (3D) distribution within the cornea was reconstructed and analyzed.

Results

The micro-CT imaging revealed exquisite details of the corneal ultrastructure, including the spatial arrangement of cells throughout its depth. This novel approach allowed for the visualization of cells' density and distribution in different corneal layers. Notably, our findings highlighted variations in cell distribution between non-hydrated and hydrated corneas.

Conclusions

This study demonstrates the potential of contrast-enhanced micro-CT as a valuable tool for non-destructive, 3D visualization and quantitative analysis of cell distribution in hydrated human corneas. These insights contribute to a better understanding of corneal physiology and may have implications for research in corneal diseases and tissue engineering.