Magnetic resonance imaging of anterior cruciate ligament tears: evaluation of standard orthogonal and tailored paracoronal images.

PURPOSE: To evaluate the three standard orthogonal imaging planes and a paracoronal imaging plane for anterior cruciate ligament (ACL) tears.

MATERIAL AND METHODS: Ninety patients (91 knees; 29 F and 61 M) aged between 15 and 84 years (mean 36.9 +/- 16.4 years) underwent magnetic resonance imaging (MRI) of the knee prior to arthroscopy. At surgery, 32 knees had an intact ACL, 4 a partial tear, and 55 a complete ACL tear. In all patients, axial, sagittal, coronal, and paracoronal T2-weighted turbo-SE images were acquired. The ACL was classified as intact, partially, or completely torn. Partial and complete tears were combined for statistical evaluation.

RESULTS: Partial ACL tears (four cases) were not correctly diagnosed at MRI except in one knee by one observer on coronal images. Sensitivity in detecting ACL tears was 95%/63% (reader1/reader2) in the axial, 93%/95% in the sagittal, 93%/86% in the coronal, and 100%/93% in the paracoronal plane. Specificity was 75%/81% in the axial, 72%/81% in the sagittal, 78%/94% in the coronal, and 78%/88% in the paracoronal plane.

CONCLUSION: ACL tears can be diagnosed accurately with each of the standard orthogonal planes. Based on reader confidence and interobserver agreement paracoronal images may be useful in equivocal cases.