A CT arthrogram may be used in place of an MRI scan, for example when a patient cannot undergo an MRI because they have a pacemaker, cochlear implant or brain aneurysm clip.
The procedure involves an injection of dye (contrast) into the knee in order to provide the soft definition and contrast to reliably diagnose the common disorders affecting the knee. In this case, note the dye extending across the knee (image 1), consistent with an absent anterior cruciate ligament (ACL) and thus the diagnosis of an ACL tear.
The posterior cruciate ligament (PCL) is intact (image 2).
The ACL tear is associated with a vertical tear through the medial meniscus, which is highlighted by the contrast dye (image 3) as well as a Baker’s cyst (image 4) which has formed from increased fluid in the joint.
Note a normal appearing lateral meniscus, which demonstrates a triangular appearance (image 5).
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