Evaluation of Diffusional Characteristics and Microstructure in Unilateral Vocal Fold Paralysis Using Diffusion...

Area of Science:

• Otolaryngology
• Neurology
• Radiology

Background:

• Recurrent laryngeal nerve (RLN) injury can lead to vocal fold paralysis and muscle atrophy.
• Accurate assessment of vocal fold microstructure is crucial for understanding and managing these changes.
• Current methods may be invasive or lack detailed microstructural information.

Purpose of the Study:

• To determine the value of diffusion tensor imaging (DTI) in assessing vocal fold tissue microstructure following RLN injury.
• To correlate DTI findings with histological changes in vocal fold muscle and lamina propria.
• To establish DTI as a viable tool for evaluating RLN-induced vocal fold atrophy.

Main Methods:

• Unilateral RLN injury was induced in four canines; two served as controls.
• After four months, larynges were imaged using a 9.4T MRI scanner.
• Vocal folds were histologically analyzed for cross-sectional area and muscle fiber density, with correlation to DTI parameters.

Main Results:

• In the muscle layer, fractional anisotropy (FA) was higher and Tensor Trace lower in the RLN injury group compared to controls (P < .05).
• In the lamina propria, FA was lower (P > .05) and Tensor Trace lower (P < .05) in the injury group.
• RLN injury group showed significantly smaller muscle fiber cross-sectional area and lower fiber density (P < .05).
• Significant correlations were found between FA/Tensor Trace and muscle fiber cross-sectional area (P < .05).

Conclusions:

• DTI is an effective method for assessing microstructural changes in atrophic vocal fold muscle tissue after RLN injury.
• DTI parameters correlate with histological evidence of muscle atrophy.
• This imaging technique offers valuable insights into vocal fold tissue alterations post-nerve injury.