MR imaging of anteromedial and posterolateral bundles of anterior cruciate ligament of knee joint

Objective To improve the visualization of anteromedial and posterolateral bundles of anterior cruciate ligament (ACL) and investigate the optimal MRI plane for the bundles at a 3.0 T MR scanner.Methods MR images of 149 knee joints were reviewed retrospectively.Display rates of AMB,PLB and their different parts (the top portion,the middle portion and the low portion) on MR different planes including axial,sagittal and coronal planes were analyzed and their differences were compared with the x2 section method.Results There was no statistical difference in the display rates of two bundles of ACL between axial plane ( 115/149,77.2％ ) and coronal plane (103/149,69.1％ ) (x2 =2.4606,P ＞0.0125 ).Statistical differences were found between axial and sagittal plane,coronal plane and sagittal plane (21/149,14.1％ ) ( x2 =119.5138,92.8695 respectively,P ＜0.0125 ).There was a statistical difference for the top portion of ACL between axial plane ( 104/149,69.8％ ) and coronal plane,sagittal (0/149,0)and coronal planes ( 7/149,4.7％ ) ( x2 =135.081,159.7526 respectively,P ＜ 0.0125 ),between sagittal and coronal planes (x2 =7.1684,P ＜ 0.0125 ).For the middle portion of ACL,there was no statistical difference between axial plane ( 108/149,72.5％ ) and coronal plane (94/149,63.1％ ) (x2 =3.0120,P ＞ 0.0125 ),while statistical differences were found between axial and sagittal plane,coronal planes and sagittal plane ( 10/149,6.7％ ) ( x2 =134.7454,104.2173 respectively,P ＜ 0.0125 ).For the low portion of ACL,there was no statistical difference between axial plane ( 103/149,69.1％ ) and coronal plane (101/149,73.8％ ) (x2 =0.8065,P ＞0.0125),while statistical differences were detected between axial and sagittal plane,coronal planes and sagittal plane ( 18/149,12.1％ ) ( x2 =100.5300,115.9132,P ＜ 0.0125 ). The different parts of ACL displayed low intensity on different MR planes and normal morphology.Conclusions ACL can be displayed on conventional MR planes at a 3.0 T MR scanner to some extent.Axial and coronal planes might be the optimal MRI planes for ACL and its two bundles. Key words: Magnetic resonance imaging;  Anterior cruciate ligament;  Knee joint