Anterior cruciate ligament: oblique sagittal MR imaging

Optimal visualization of the anterior cruciate ligament with magnetic resonance imaging requires oblique sagittal imaging planes. Between 10 degrees and 20 degrees of external rotation of the knee is considered ideal. While the knee may normally assume this amount of obliquity in the relaxed position, the orientation of the imaging plane is not guaranteed. Many imagers can perform oblique sagittal imaging, but the operator must set the proper degree of obliquity for the examination. A simple template was devised to facilitate this process, resulting in more consistently oriented imaging planes. The template can be reproduced by photocopying the diagram provided onto a transparency.