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Thursday, March 11, 2004

Knee MRI studies can lead to unjustified surgeries

By Nancy Fehr

There can be a significant discrepancy between diagnosis based on magnetic resonance imaging (MRI) and surgical finding, according to researchers presenting Scientific Paper 11 on Wednesday. In their retrospective study, the authors compared the reliability of knee MRIs under conditions of various levels of expertise in a multi-institutional analysis and reviewed the factors affecting the accuracy of the results and the interpretations of knee MRI studies.

They found that 37 percent of the operations supported by significant MRI pathology were unjustified.

MRI of the knee is commonly performed for diagnosing disorders in and around the knee, because the high soft-tissue resolution allows precise imaging of intra-articular structures such as ligaments, cartilage and menisci. MRI of the knee is reported to have a greater than 90 percent accuracy rate in detecting intra-articular pathology when it is performed in specialized medical centers and interpreted by specialists in musculoskeletal MRI radiology.

Researchers analyzed all knee MRI reports between 1997 and 1998 of soldiers who subsequently underwent primary arthroscopic surgery of the knee within six months.

MRI results were compared to surgical findings of four structures:

Of the 633 MRIs of the knee and 1185 arthroscopies that were performed in 14 institutions during the study period, 139 paired MRI-arthroscopic reports fulfilled the study's inclusion criteria. When compared to surgical findings, the MRI pathology results showed a false positive rate of:

The respective accuracy rates were 52 percent, 82 percent, 80 percent and 77 percent.

"To be of real value, MRI for the examination of injured knees should follow specific knee MRI protocols and be performed, supervised and interpreted by experienced specialized musculoskeletal radiologists," said lead author Peleg Ben-Galim, MD, of Modiin, Israel.

We found that medical insurers usually prefered contracts with 'cheaper' imaging facilities and did not have any quality control assurance regarding accuracy of MRI. Orthopaedic surgeons must be made aware of the vast differences that may occur in the accuracy of MRI and the reliability of its interpretation. With the ongoing evolution of more sophisticated MRI modalities and subtraction images, it is imperative that orthopaedic surgeons establish a qualitative feedback relationship with musucloskeletal radiologists so that quality control may be assured. The medical insurers should be informed of the high costs of being penny-wise," he added.

In addition to Dr. Ben-Galim, study authors included Ely Steinberg, MD, Nahman Ash, MD, Hagai Amir, MD, and Ron Arbel, MD, all of Tel Aviv, Israel.

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Last modified 20/February/2004