Non-invasive Evaluation Of Pathological Microstructure And Biomechanical Properties Of Vocal Folds In Vocal Fold Paralysis And Cricoarytenoid Joint Dislocation By Diffusion Tensor Imaging

Vocal vibration of vocal fold is very important to the communication of daily life.The occurrence of voice disorders will disturb the vocal fold vibration and affect people’s daily life quality.Because of the particularity of vocal fold structure and function,we need to deeply understand the microstructure and biomechanical characteristics of normal vocal fold tissue.At the same time,during the formation of vocal fold disorders,the change of vocal fold vibration is also related to the change of microstructure of vocal fold which affects the biomechanical characteristics of vocal fold.However,there is no effective method to evaluate the microstructure and biomechanical characteristics of vocal fold.Therefore,it is of great significance to study the correlation between the microstructure and the biomechanical properties of vocal fold and the changes under the pathological state,and the objective and quantitative measurement of the biomechanical properties of human vocal fold.We will explain this problem in the following three parts.In the first study,the vocal fold stretching model of excised canine larynx was constructed,combined with diffusion tensor imaging(DTI)technique,the results show that with the increase of stretching gradient,the diffusion tensor parameter FA increased and Tensor Trace decreased in vocal fold muscle fiber.This study explored the changes of FA and Tensor Trace in the microstructure of vocal fold under different stretching conditions.It also laid a foundation for DTI to objectively and quantitatively evaluate the micro pathological structure and biomechanical properties of vocal folds.In the second study,the pathological model of RLN injury was constructed.Combined with pathological feature extraction technology,in vitro dog laryngeal phonation experiment and DTI technology,the results showed that ① after RLN injury,the vocal fold tissue atrophy,the cross-sectional area of vocal fold muscle decreased,and the muscle content decreased;② The difference of acoustic parameters such as jitter,shimmer and mucosal wave parameters such as amplitude,phase were larger than that of the control group;③ the diffusion characteristics of water molecules in vocal fold tissue changed,FA in vocal fold muscle layer increased,and Tensor Trace decreased.The results indicate that the changes of microstructure and biomechanical properties of vocal fold after RLN injury and their effects on vocal fold vibration.DTI is an effective method to detect the microstructure and biomechanical properties of vocal fold.In the third study,a beagle dog model of vocal fold paralysis and cricoarytenoid joint dislocation was constructed.Combined with pathological feature extraction technology and DTI technology,the results showed that ① the cross-sectional area and muscle content of vocal fold muscle fibers in the vocal fold paralysis group were smaller than those in the cricoarytenoid joint dislocation group;②compared with the cricoarytenoid joint dislocation group,the FA in the vocal fold paralysis group was larger,and Tensor Trace is smaller.The results indicate that there are significant differences in the microstructure and biomechanical properties of vocal fold in the pathological state of vocal fold paralysis and cricoarytenoid joint dislocation,and DTI can be used as an effective method to distinguish the differences in the microstructure and biomechanical properties of vocal fold between vocal fold paralysis and cricoarytenoid joint dislocation.Through these studies,we have a further understanding of the mechanism that the microstructure and biomechanical properties of vocal fold affect the vocal fold vibration function.At the same time,DTI is applied to the study of pathological microstructure and biomechanical properties of vocal folds for the first time in this paper,and a new non-invasive objective quantitative evaluation method is proposed to explore the microstructure and biomechanical properties of vocal folds.It is very important to understand the microstructure of vocal fold and how the microstructure affects the biomechanical properties of vocal fold,so as to affect the vocal fold vibration.All of these are helpful to better understand the mechanism of the occurrence and development of voice disorders,and to make more accurate diagnosis of voice disorders and more appropriate treatment for voice disorders.