Analysis On False Positive And False Negative Of MRI Diagnosis In Torn Anterior Cruciate Ligament

Objective:We compared MRI diagnosis with clinical diagnosis of anterior cruciate ligament injury to explore the important value in the MRI diagnosis of anterior cruciate ligament injury.Methods:From September in 2007 to December in 2008, there are 136 cases suspected anterior cruciate ligament injury through clinical diagnosis compared with subsequent MRI and arthroscopy examination. Clinical examination includes anterior draw test, Lachman test, pivot shift test .MRI we used with 1.5T fields was Signa type,produced by GE company in the US,arthroscopies we used with 4.0 mm diameter and 30 degrees wide angle,produced by Smith & Nephew Inc and Stryker Corporation.The results of MRI examination were diagnosed by an experienced radiological doctor.The doctor with experience of thousands of arthroscopic operation in clinical operated on the patients after MRI.Then we compared these two kinds of diagnoses and analysed the differences between them.Result: In our study,136 anterior cruciate ligaments were diagnosed with the result that 86 normal anterior cruciate ligaments and 50 abnormal anterior cruciate ligaments in MRI diagnosis,To the results of arthroscopy as the standard, MRI diagnostic results:76 true-positive, 47 true-negative,10 false-positive and 3 false-negative.Analysis of 10 false-positive patients for the following reasons:(1)Degeneration of anterior cruciate ligament(2)Structure artifacts (3)Scanning direction and the anterior cruciate ligament is not the direction parallel.(4)Anterior cruciate ligament injury healed scar(5)Partial volume effects lead to a false impressionAnalysis of 3 false-negative patients for the following reasons:(1)Chronic torn anterior cruciate ligament thickness increase usually without edema, similar to the normal ACL.(2)Torn anterior cruciate ligament attached to posterior cruciate ligament, similar to the normal ACL.(3)May be due to improperly positioned, or because the average volume of cruciate insufficient, or both lead to the anterior cruciate ligament of the sagittal image have not been successful on display.Conclusion:MRI is a better means of inspection for the diagnosis of anterior cruciate ligament injury, but there is false positive and false negative. For the diagnosis of anterior cruciate ligament injury, clinical examination and MRI should be the combination and can not be over-reliance on MRI examination.