Session: 06-11-03: Biotechnology and General Applications

Paper Number: 140971

140971 - Quantifying the Fascicular Changes in Recovered Achilles Tendon Patients Using Diffusion Mri and Tractography 

Regardless of the way of treatment, persistent deficits in calf muscles in recovered patients from Achilles Tendon Rupture (ATR) exist long-term post-injury. There are studies on calf muscle highlighting reduced cross-sectional area and volume of the Gastrocnemius and Soleus muscle, and the increases of fat infiltration. However, limited attention has been given to fascicular changes and alternation. Diffuse tensor imaging (DTI) is a valuable technique that can be used to understand tissue properties such as mean diffusivity (MD) and fractional anisotropy (FA). In the current study, we used DTI-derived indices (MD, FA, and eigen values - λ₁, λ₂, and λ₃) and fiber tractography to better understand the Soleus muscle after recovery from ATR. We recruited five participants who had recovered from ATR in one leg (2 females and 3 males, with an average age of 45.6 ± 16.5 years, weight of 85.6 ± 17.6 kg, and height of 174.8 ± 3.4 cm). Anatomical (T1) and DTI images of the soleus muscle near the Achilles tendon were acquired using a a 15-channel knee coil on 3T MRI (Siemens Prima Fit). Subsequently, DTI images were corrected for potential eddy current distortions and motion artifacts using DSI Studio.  A region of interest (ROI) surrounding the lower end of the soleus muscle was separated using ROIEditor in DTIStudio. Using MRtrix, we extrcated various DTI indices to probe the diffusion integrity in the muscles. Here we focused on the MD and FA in soleus. These parameters were used to compare the results of injured legs and healthy ones. In the second part of this study, we performed fiber tractography and the tractography-derived parameters were computed for all the subjects within the lower region part of the soleus muscle. Our findings showed varying degrees of fat infiltration and atrophy in the soleus muscle. The mean values of parameters of (FA, MD, and eigenvalues) across participants did not show consistent trends when the subsections of the soleus muscle were excluded. However, we observed higher standard deviations of measured parameters within the ROI in the injured legs compared to the healthy legs across all subjects. Further statistical analysis, (for example, two-sample t-test: 0.085 for λ₁ and 0.049 for λ₂) underscored that the average standard deviation over the ROI for all participants is a robust indicator of the differences between healthy and injured leg. When contrasted with their healthy counterparts, it effectively demonstrates the inhomogeneity of fascicles in injured legs. Additionally, in 4 out of 5 participants, smaller tracts were observed in the injured leg compared to the healthy one, as evidenced by the fiber length distribution of the tracts.

Presenting Author: Shabnam Rahimnezhad The Pennsylvania State University

Presenting Author Biography: Shabnam Rahimnezhad is pursuing a doctoral degree in the Department of Mechanical Engineering under the guidance of Dr. Daniel Cortes. Her research focuses on biomedical projects, particularly in the areas of rehabilitation and imaging. Prior to her doctoral studies, she obtained both bachelor's and master's degrees from the Iran School of Automotive Engineering. Her interest in understanding injury mechanisms led her to delve deeper into biomechanics, prompting her to pursue a second master's degree in Biomedical Engineering from Wayne State University. Following her academic pursuits, she gained experience through a year-long stint at Henry Ford Hospital and Xenith football helmet. She earned her third master's degree in Mechanical Engineering.

Authors:

Shabnam Rahimnezhad The Pennsylvania State University
Tanzil Arefin The Pennsylvania State University
Xiaoxiao Bai The Pennsylvania State University
Thomas Neuberger The Pennsylvania State university
Daniel Cortes The Pennsylvania State University