2016 Two-Year Clinical Nerve Research Grant Progress Report

October 16, 2017

Impact of Carpal Tunnel Syndrome and Diabetes on Nerve Structure

PI: Sameer B. Shah, PhD, University of California, San Diego
Co-PI: Reid A. Abrams, MD, University of California, San Diego

Drs. Shah and Abrams, along with their collaborators Dr. Jiang Du and Dr. Eric Chang, started work on their 2-year study in January 2017 and have demonstrated remarkable progress! The authors had proposed new methods for high resolution imaging of peripheral nerves. MRI approaches were proposed to complement ultrasound-based imaging strategies, to rapidly and reliably detect regional changes in nerve kinematics. As an initial test of their new imaging methods, they proposed to examine structural and mechanical changes in the context of carpal tunnel syndrome and/or diabetic neuropathy.

The authors’ specific aims were: (1) to validate new MRI-based imaging methodology by comparing control and diabetic median nerves; and (2) to compare regional changes in structural and kinematic outcomes in median nerves of individuals with CTS, diabetes, or both using MRI- and ultrasound-based imaging.

Dr. Shah reports:

“Peripheral nerves are a composite tissue consisting of neurovascular elements packaged within a well-organized and extensive extracellular matrix. Their composition, size, and anatomy render nerves a challenging medical imaging target. Evaluation of structure using conventional morphological MRI sequences is fundamentally limited by resolution and time.

With highly optimized conventional sequences focused on a very small field of view, resolution can approach 0.1 mm with 10-12-minute acquisition time, which is sufficient to resolve the perineurium of larger, more superficial nerves. In contrast to morphological imaging approaches, quantitative MRI sequences can provide structural information on a submicron to micron scale. We have developed ultrashort time to echo (UTE) imaging approaches to provide quantitative data on nerve structure. [To date with our study], we have successfully demonstrated the potential utility of several quantitative MR methods to assess differences in nerve structure and macromolecular content, including collagen. 

In particular, single component T2* analysis, bi-component T2* analysis, and magnetization transfer (MT) imaging with UTE pulse sequences are feasible for imaging peripheral nerves. [Also], we have piloted ultrasound methods to image nerve morphology in human subjects. Using the VevoMD high-frequency clinical imaging system, we can quantify fascicular geometry and kinematics during joint movement. [In the next stage of our study], we will begin applying MRI and ultrasound approaches to imaging control subjects and those with neuropathy.”

This project received funding from the American Foundation for Surgery of the Hand for a two-year $100,000 clinical research grant on the topic of nerve.