Concentration-dependent specimen shrinkage in iodine-enhanced microCT

Area of Science:

• Biomedical Imaging
• Microscopy Techniques
• Histology

Background:

• Iodine potassium iodide (I2 KI) is used as a contrast agent for micro-computed tomography (micro-CT) of soft tissues.
• High-resolution soft tissue imaging with micro-CT is valuable for morphological studies.
• Previous studies indicated potential specimen shrinkage with I2 KI staining.

Purpose of the Study:

• To quantify macroscopic volume changes in mouse tissues fixed with common agents and stained with I2 KI.
• To compare shrinkage caused by I2 KI with that from standard fixatives (formalin, ethanol, glutaraldehyde).
• To determine the effect of I2 KI concentration on tissue shrinkage.

Main Methods:

• Mouse skeletal muscle, cardiac muscle, and cerebellum were immersed in 10% phosphate-buffered formal saline, 70% ethanol, or 3% glutaraldehyde.
• Tissues were also immersed in I2 KI solutions at concentrations of 2%, 6%, 10%, and 20%.
• Macroscopic volume changes were quantified after 14 days of incubation.

Main Results:

• I2 KI staining caused significantly greater tissue volume changes than formalin fixation alone.
• Tissue shrinkage was highly dependent on I2 KI concentration.
• A severe shrinkage of 70% was observed with 20% I2 KI after 14 days.

Conclusions:

• Iodine potassium iodide staining leads to substantial specimen shrinkage, potentially impacting morphological analysis in micro-CT.
• The degree of shrinkage is directly related to I2 KI concentration.
• To minimize artifacts, it is crucial to use the lowest I2 KI concentration that provides adequate contrast for soft tissue visualization.