Radiology, Vol 196, 617-621, Copyright © 1995 by Radiological Society of North America
Error patterns in the MR imaging evaluation of menisci of the knee
WW Justice and SF Quinn
Department of Radiology, Oregon Health Sciences University, Portland, USA.
PURPOSE: To categorize errors in interpretation of magnetic resonance (MR)
images of the knee and explain the discrepancy between MR imaging and
diagnostic arthroscopic findings. MATERIALS AND METHODS: Five hundred
sixty-one patients underwent arthroscopy and MR imaging of the knee.
Prospective and retrospective readings were used to categorize tear type
and location. Sixty-six patients had 68 discrepancies between MR imaging
and arthroscopic findings. RESULTS: Prospective interpretation of MR images
of the lateral meniscus had a sensitivity of 82%, specificity of 98%, and
accuracy of 93%. For images of the medial meniscus, sensitivity was 96%;
specificity, 91%; and accuracy, 95%. The number of diagnostic errors at
retrospective analysis was 76% (n = 52) of the number at prospective
analysis. CONCLUSION: MR imaging is accurate in evaluation for meniscal
tears. Most errors in interpretation that occur at prospective evaluation
also occur at retrospective evaluation. Some false-positive errors may be
related to incomplete arthroscopic evaluation of the meniscus and confusion
between what represents fraying and what represents a tear.
