The value of the sagittal-oblique MRI technique for injuries of the anterior cruciate ligament in the knee

Abstract

BackgroundComplete rupture of the anterior cruciate ligament (ACL) does not represent a diagnostic problem for the standard magnetic resonance (MR) protocol of the knee. Lower accuracy of the standard MR protocol for partial rupture of the ACL can be improved by using additional, dedicated MR techniques. The study goal was to draw a comparison between sagittal-oblique MR technique of ACL imaging versus flexion MR technique of ACL imaging and, versus ACL imaging obtained with standard MR protocol of the knee.Patients and methodsIn this prospective study we included 149 patients who were referred to magnetic resonance imaging (MRI) examination due to knee soft tissues trauma during 12 months period. MRI signs of ACL trauma, especially detection of partial tears, number of slices per technique showing the whole ACL, duration of applied additional protocols, and reproducibility of examination were analysed.ResultsAccuracy of standard MRI protocol of the knee comparing to both additional techniques is identical in detection of a complete ACL rupture. Presentations of the partial ruptures of ACL using flexion technique and sagittal-oblique technique were more sensitive (p<0.001) than presentation using standard MR protocol. There was no statistically significant difference between MRI detection of the ruptured ACL between additional techniques (p> 0.65). Sagittal-oblique technique provides a higher number of MRI slices showing the whole course of the ACL and requires a shorter scan time compared to flexion technique (p<0.001).ConclusionsBoth additional techniques (flexion and sagittal-oblique) are just as precise as the standard MR protocol for the evaluation of a complete rupture of the ACL, so they should be used in cases of suspicion of partial rupture of the ACL. Our study showed sagittal-oblique technique was superior, because it did not depend on patient’s ability to exactly repeat the same external rotation if standard MR protocol was used or to repeat exactly the same flexion in flexion MR technique in further MR examinations. Sagittal-oblique technique does not require the patient’s knee to be repositioned, which makes this technique faster. We propose this technique in addition to the standard MR protocol for detection of partial ACL tears.

Diagnostic Value of Oblique Coronal and Oblique Sagittal Magnetic Resonance Imaging (MRI) in Diagnosis of Anterior Cruciate Ligament (ACL) Tears

“…Moreover, they found that sagittal-oblique images require a shorter scan time compared to the flexion technique due to a higher number of MRI slices that show the whole course of the ACL. [ 13 ]…”

Visualization of torn anterior cruciate ligament using 3-dimensional computed tomography

“…Recent progress in MRI techniques such as sagittaloblique technique and 3D fast spin echo may make it possible to identify the remnant ACL fibers because they can depict a partial ACL tear, 13,14 but they are not available in every institute. By standard MRI, complete ACL tears can be detected but there may be some difficulty in identifying remnant ACL 15 .…”

MRI of the Knee: What Do We Miss?

“…13). Additionally, dedicated MR protocols, including imaging the knee in a slightly flexed position or acquiring images in a sagittal oblique plane, can improve the diagnostic yield of partial tears [37,38]. When the knee is in flexion, there is improved accuracy secondary to the loss of volume averaging in the intercondylar notch.…”