Accuracy of magnetic resonance imaging in the knee

To determine the accuracy of magnetic resonance imaging (MRI) in the assessment of various knee disorders in comparison with arthroscopic findings and pathologic diagnosis.

A retrospective and comparative study.

Radiology Department, Aga Khan University Hospital, Karachi, from 01-12-1996 to 30-06-2000.

Fifty-six subjects (36 males and 20 females), included in this study, had abnormal findings on MRI, which were correlated with arthroscopic findings in 50 cases and pathological diagnosis in 6 cases. Plain X-rays were available in all cases.

The sensitivity, specificity and accuracy for MRI of the menisci and cruciate ligaments were as follows: medial meniscus pathologies 87% sensitivity, 94% specificity and 92% accuracy; lateral meniscus pathologies 92% sensitivity, 89% specificity and 90% accuracy; anterior cruciate ligament injuries 95% sensitivity, 96% specificity and 96% accuracy and posterior cruciate ligament injuries 100% sensitivity, 98% specificity and 98% accuracy. Pathological diagnosis was available in 6 cases. MR imaging suggested the diagnosis of tuberculosis and metastases as well as mapped out the extent of osteogenic sarcoma, fibromatoses and rhabdomyosarcoma.

This study confirms that MR imaging of the knee is highly sensitive, specific, and accurate.