Magnetic resonance images of the knee were made for 1014 patients, and
the diagnosis was subsequently confirmed arthroscopically. The accuracy of
the diagnoses from the imaging was 89 per cent for the medial meniscus, 88
per cent for the lateral meniscus, 93 per cent for the anterior cruciate
ligament, and 99 per cent for the posterior cruciate ligament. The magnetic
resonance examinations were done at several centers, and the results varied
substantially among centers. The accuracy ranged from 64 to 95 per cent for
the medial meniscus, from 83 to 94 per cent for the lateral meniscus, and
from 78 to 97 per cent for the anterior cruciate ligament. The results from
different magnetic-resonance units were also compared, and the findings
suggested increased accuracy for the units that had a stronger magnetic
field. Of the menisci for which the magnetic resonance signal was reported
to be Grade II (a linear intrameniscal signal not extending to the superior
or inferior meniscal surface), 17 per cent were found to be torn at
arthroscopy.