Wei Li, Martin Lazarus, Jason Koh, Ewa Gliwa and Pottumarthi V Prasad
Purpose: To assess the feasibility of performing intra-articular dGEMRIC in patients scheduled for MR arthrography of the hip joint, specifically to evaluate whether using fixed amount of contrast agent and applying additional medications to joint cavity influence the dGEMRIC index.
Materials and methods: Thirty-nine patients with hip pain, who had standard MR imaging of hip joint and longitudinal relaxation time (T1) mapping data following intra-articular administration of gadopentetate (Gd-DTPA2-) on either a 1.5T or 3.0T scanner, were reviewed. The T1s of articular cartilage and synovial fluid were analyzed with two-tailed t-test and regression analysis based on the presence or absence of morphological cartilage damage. A phantom study to mimic the synovial fluid changes during arthrography procedure was performed.
Results: T1 measured in damaged cartilage was significantly lower compared to global T1 value of cartilage in the same joint at both 1.5T (p<0.05) and 3.0T scanners (p<0.01). However, the T1 of articular cartilage and synovial fluid showed large inter-subject variation. Moderate correlations in T1 were observed between global cartilage and synovial fluid at both 1.5T (R=0.53, p<0.03) and 3T (R=0.45, p<0.05). The phantom study suggested an apparent direct influence of iohexol on T1 measurements.
Conclusion: ia-dGEMRIC may be useful to differentiate cartilage T1s within a joint based on health status. However, inter-subject comparison is limited because of the large variability in cartilage T1 between subjects. This limitation may be related to using of a fixed amount of contrast agent without normalization and applying additional medications to the joint cavity.