Mayo Clinic Researchers Develop New Imaging Technique for Assessing Wrist Joint Instability
With funding from the Mayo Clinic Center for Translational Science Activities (CTSA) through a Novel Methodology Development Award, a group of Mayo investigators has developed an innovative imaging methodology to detect subtle joint instabilities. The study, a collaborative effort between the Departments of Radiology and Orthopedics at Mayo Clinic, sought to employ a novel imaging technique — 4-dimensional computed tomography (4-D CT), with time as the fourth dimension — to dynamically capture bony motion.
Based on data from this study, the investigative team recently received a favorable score on their National Institutes of Health (NIH) R21 grant application titled "Quantitative Assessment of Dynamic Joint Instabilities Using 4-D CT Imaging." They expect funding to be received in summer 2010. The R21 grant mechanism is designed to encourage new, exploratory and developmental research projects.
Clinical importance
At present, clinicians diagnose abnormal joint motion using subjective techniques that have high false-positive rates. In fact, dynamic instabilities can cause patients severe pain while continuing to go undetected on routine radiographic examinations.
With a dynamic joint instability that goes undiagnosed, a patient will experience progressive degenerative disease that eventually results in functional disabilities or osteoarthritis. But if caught early, the condition can be treated before it evolves into something more serious.
Study method and results
"We used cadaveric wrist joints to evaluate two separate dynamic 4-D CT imaging methods — a retrospectively gated scan technique and a non-gated sequential scan technique — and assessed them both for image quality and radiation dose," says Cynthia McCollough, Ph.D., director of the Mayo Clinic CT Clinical Innovation Center and principal investigator of the study.
With the retrospectively gated technique, the team learned that acceptable image quality could only be obtained when periodicity of joint motion was maintained. Non-periodic motion led to banding artifacts; since patients may have difficult keeping perfect periodic motion, they found that application of the retrospectively gated technique is limited.
On the other hand, the non-gated sequential technique did not require periodicity of wrist motion, and generated high spatial and high temporal resolution images of the joint. As the team was also able to keep the radiation dose from this technique very low, this second method was the preferred one of the two in the study — with the caveat that the scanner only allows for imaging of small joints, such as the wrist and carpometacarpal joint.
"Our results demonstrate that high spatial resolution and high temporal resolution images can be obtained for qualitative and quantitative kinematic analysis and diagnosis of pathology," says Dr. McCollough.
Next steps
Dr. McCollough and colleagues are presenting their findings at The First International Meeting on Image Formation in X-Ray Computed Tomography on June 6-9. They are also finalizing a protocol that will move their research into human trials; the team hopes to enroll participants by this summer.
"This methodology holds tremendous potential in assisting clinicians treating patients with wrist pain caused by abnormal motion of the wrist bones. The wrist is composed of multiple irregularly shaped bones, which means imaging with conventional technology is of limited usefulness," says Richard Berger, M.D., Ph.D., a Mayo Clinic orthopedic surgeon and study co-investigator.
Dr. McCollough adds, "This study really shows that relatively small amounts of funding can go a long way toward improving clinical practice. Funding from the Mayo Clinic CTSA is what made this study possible, and we're excited to test our findings in clinical studies."
The Mayo Clinic research team also included Kai-Nan An, Ph.D.; Shuai Leng, Ph.D.; Naveen Murthy, M.D.; and Kristin Zhao.
About the CTSA and the Novel Methodology Development Award
The largest research-related center at Mayo Clinic, the CTSA supports the "infrastructure" that enables Mayo investigators to perform cutting-edge clinical research. In 2006, Mayo Clinic became one of the first 12 institutions in the nation to receive a Clinical and Translational Science Award from the National Institutes of Health (NIH). This five-year, $72.5 million grant seeks to speed the translation of research results into therapies, tools and patient care practices that improve community health.
The development of novel clinical and translational methodologies is a key part of the CTSA's charge. To encourage such research, the Mayo Clinic CTSA established the competitive Novel Methodology Development Award. This award provides funding of up to $50,000 for one year to facilitate development of state-of-the-art tools and innovative modifications of existing methods for translational research and to make them rapidly available to clinical investigators.
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