MR Metal Imaging
In the Section of Musculoskeletal Imaging at NYULMC, we are actively engaged in research dedicated to the evaluation of pathology in patients with metallic implants. For many years, imaging in patients with such implants has been limited to plain radiography and nuclear imaging with incomplete evaluation of the soft tissue structures surrounding the metallic implant. Recent advances in the design of certain implants have led, in some instances, to a unique set of complications, many of which affect predominantly the joint capsule and surrounding musculotendinous structures. MRI, though capable of exquisite delineation of osseous and soft tissue anatomy, is subject to extensive artifact and distortion in proximity to metallic implants. This can make evaluation of complications related to these implants difficult, if not impossible, in some cases.
To a degree, this artifact can be reduced by applying certain principles of physics to the standard imaging sequences already employed at most centers. At NYU, we are working to perfect these modifications, as well as collaborating with Siemens in regards to the use of a novel imaging sequence developed by their physicists called SEMAC. Utilizing a combination of these various techniques, we have arrived at what we believe to be the most comprehensive examination possible in the presence of large metallic implants. This has made it possible for our surgeons to get valuable information which can help determine the need for surgical intervention and provide pre-operative planning which can aid in the reduction of operating room time and complication rates.
We are continually working on optimization of these techniques and are actively engaged in review of early results as they correlate with findings at surgery. We hope, by this process, to improve both the quality of the imaging as well as reduce scan times and increase patient comfort.
Examples of STIR images obtained in the coronal plane without (A) and with (B) SEMAC technique applied. A dramatic reduction in the degree of metal induced artifact around the implant can be noted with the SEMAC technique.