MR Technology Addresses Growing Need for Imaging Soft Tissue around Metal Implants

An innovative magnetic resonance imaging (MRI) technique has been designed to tackle the growing clinical need to more effectively image soft tissue and bone in patients with MR-conditional-labeled implants, such as joint replacements and other instrumentation.

According to a recent study conducted at the Hospital for Special Surgery and published May 24, 2013, in the Journal of Bone & Joint Surgery, MR imaging can detect inflammation of the synovitis in patients with metal-on-metal hip implants long before symptoms present, allowing for a more conclusive diagnosis and effective planning for follow-up care.

At a recently held event at the Hospital for Special Surgery (New York, NY, USA), GE Healthcare (Chalfont St. Giles, UK) introduced the Mavric SL system. “Even in asymptomatic patients, the Mavric SL technology can recognize an issue that needs to be monitored, providing valuable clinical information for an issue that can have significant human and economic costs, particularly when diagnosis is delayed,” stated a GE spokesperson.

There are more than 1 million hip or knee replacement (arthroplasty) procedures performed yearly in the United States, and more than 250,000 procedures are performed in Europe per year. The need for arthroplasty revision procedures (a second surgery to correct the failure of an artificial joint) is increasing substantially due to the increased frequency of joint replacements and the younger ages at which they are being performed. It is predicted that by 2030, the number of revision procedures will increase by 137% for hips and 601% for knees from 2005.

Patients with complications from joint replacement surgeries may present with pain and/or altered gait mechanics, or may have no symptoms at all. Before the availability of Mavric SL, achieving quality diagnostic MR images of the anatomy near implants was often not possible due to image distortion caused by metal used in implanted devices. Mavric SL reduces image distortion in the regions near MR Conditional metal implants, enabling physicians to see tissue surrounding an implant to help them with diagnosis and defining a course of treatment. In some cases, Mavric SL can reduce the need for biopsy or exploratory surgery.

“The addition of Mavric SL to a standardized MR protocol is instrumental in providing accurate, reproducible diagnosis of adverse tissue reactions around implants,” said Dr. Hollis Potter, chief of MR Imaging at Hospital for Special Surgery, and a lead member of the development team. “Even in asymptomatic patients, the Mavric SL technology can recognize an issue that needs to be monitored, providing valuable clinical information for an issue that can have significant human and economic costs, particularly when diagnosis is delayed.”

According to data published by Hospital for Special Surgery, patients may be experiencing tissue damage from metal-on-metal hip implants before pain symptoms appear. MR imaging was able to detect inflammation in both symptomatic and asymptomatic patients, helping to identify those patients who may need revision surgery before the surrounding tissue sustains further damage that makes revision more difficult. The study findings also emphasized that typically used markers for tissue damage are insufficient in their ability to accurately identify those patients who may require revision surgery.

“The development of the Mavric protocol has given us a window into the local tissue response to implants and a better understanding of the underlying cause of patients’ pain and poor function,” said Mathias P. Bostrom, MD, attending orthopedic surgeon, Hospital for Special Surgery. “It is well established that there is more morbidity associated with revision in the setting of severe tissue loss, and MAVRIC SL positions clinicians to provide an early and accurate diagnosis.”

Mavric SL was developed as an innovative solution to a major clinical problem, developed as a result of a collaborative effort between GE, Hospital for Special Surgery, and Stanford University (Stanford, CA, USA). It is one of the latest products in GE’s MR range designed to increase access to MR imaging for patients with metallic implants, all while maximizing patient care and reducing costs on the patient and healthcare system as a whole.

Mavric SL is a combination of an acquisition technique and postprocessing software designed for use on GE 1.5T and 3.0T MR systems. The technology is suitable for use on all patients with passive MR-conditional orthopedic implants that are scanned according to the conditions of safe use for the specific MR-conditional implant being scanned. Moreover, Mavric SL is suitable for use on patients without implants that are cleared for MR exams. Mavric SL helps reduce artifacts caused by presence of metal in both in-plane and through-plane dimensions compared to conventional MR imaging techniques. Therefore, the system allows visualizing more tissue in the neighborhood of MR-conditional implanted metal instrumentation. When interpreted by a trained physician, images generated by Mavric SL provide data that can be useful in determining a diagnosis. It is radiation-free, noninvasive, and needle-free because it requires no contrast media injection. Mavric SL received Food and Drug Administration (FDA) 501(k) clearance in December 2012 and is available in most markets.

Related Links:
Hospital for Special Surgery
GE Healthcare