PROJECT SUMMARY/ABSTRACT
Rotator cuff tears are a common source of pain and disability in the upper extremity, occurring up to 50-80% in
an elderly population. Surgical treatment is normally considered for patients who fail in non-operative
management, have an acute tear, or are unable to participate in their normal daily activities despite a course of
physical therapy. However, failure of tendon healing after rotator cuff surgery is a common complication. Multiple
studies have demonstrated that preoperative tear size, patient age, and muscle quality are critical factors to
determine surgical outcomes, but there is a need for improved non-invasive evaluation methods to assess
tendon and muscle quality to determine optimal treatment strategy.
The goals of this research project are to develop quantitative MRI methods for evaluating tendon and muscle
quality, to assess the sensitivity of developed MRI methods to degeneration in comparison to histological
analysis, and to evaluate tendon and muscle quality changes due to surgery. First, quantitative ultrashort echo-
time methods will be developed to evaluate the rotator cuff tendons, which consist of highly-ordered collagen
fiber structures resulting in a short T2 relaxation time. The quantified parameters will be compared between
controls and patients having full-thickness rotator cuff tears, and MR quantification will be compared with semi-
quantitative histologic grades of tendon samples acquired during surgery for the patient group. Second, muscle
quantitative imaging techniques will be developed for two different purposes, to evaluate fibrosis and fat fractions
simultaneously and to discriminate fat tissue as either beige or white fat. Muscle fibrosis has not been quantified
much due to its short T2* relaxation time, but UTE multi-echo images will allow the quantification of muscle
fibrosis as well. A potential of the presence of beige fat in the rotator cuff muscles after tendon tears has been
shown, which is important because beige fat can promote muscle regeneration and healing. We will also develop
accurate fat quantification technique to define beige fat. Third, a longitudinal study will be performed with patients
having full-thickness rotator cuff tears before and after surgery using developed tendon and muscle evaluation
techniques, and tendon and muscle quality changes due to surgery will be evaluated. Statistical analysis to
determine important imaging metrics that affect clinical functional outcomes will be performed, too. This proposed
approach includes comprehensive biomarkers of structural, micro-structural, and biochemical changes, and aims
for fully quantitative imaging for more precise assessments.
The proposed research and training plans are designed for the candidate to gain further knowledge in
musculoskeletal biology and statistics, and expertise in clinical research design and methodologies while
extending her MRI technical skills. The K01 grant award will help the candidate to be an independent imaging
scientist in the musculoskeletal field.