Use of intra-articular carbon dioxide and air for MR arthrography: a feasibility study.

During animal experiments, carbon dioxide (CO(2)) and air were used as a novel contrast agent for direct magnetic resonance arthrography (MRAr). MRAr was performed after injection of CO(2) and air in the knee joints of two pigs. MR images of phantoms containing air, CO(2) and nitrogen were compared. After intra-articular injection, both present as a signal void on various sequences and permit sharp delineation of cartilage and other adjacent structures. Despite the potential for artefact generation, only a slight susceptibility artefact was seen after injection of CO(2) and air. In phantom experiments, air, CO(2) and nitrogen demonstrated identical slight regular susceptibility artefacts at the phantom margins. CO(2) MRAr can yield high contrast between cartilage, ligaments and synovium relative to the joint compartment. Therefore, this technique might be useful as an investigational method for the evaluation of cartilage surface lesions and possibly as an alternative contrast agent for clinical use.