In vivo comparison of delayed gadolinium-enhanced MRI of cartilage and delayed quantitative CT arthrography in imaging of articular cartilage

SummaryObjectiveTo compare delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) and delayed quantitative computed tomography (CT) arthrography (dQCTA) to each other, and their association to arthroscopy. Additionally, the relationship between dGEMRIC with intravenous (dGEMRICIV) and intra-articular contrast agent administration (dGEMRICIA) was determined.DesignEleven patients with knee pain were scanned at 3 T MRI and 64-slice CT before arthroscopy. dQCTA was performed at 5 and 45 min after intra-articular injection of ioxaglate. Both dGEMRICIV and dGEMRICIA were performed at 90 min after gadopentetate injection. dGEMRIC indices and change in relaxation rates (ΔR1) were separately calculated for dGEMRICIV and dGEMRICIA. dGEMRIC and dQCTA parameters were calculated for predetermined sites at the knee joint that were International Cartilage Repair Society (ICRS) graded in arthroscopy.ResultsdQCTA normalized with the contrast agent concentration in synovial fluid (SF) and dGEMRICIV correlated significantly, whereas dGEMRICIA correlated with the normalized dQCTA only when dGEMRICIA was also normalized with the contrast agent concentration in SF. Correlation was strongest between normalized dQCTA at 45 min and ΔR1,IV (rs = 0.72 [95% CI 0.56–0.83], n = 49, P < 0.01) and ΔR1,IA normalized with ΔR1 in SF (rs = 0.70 [0.53–0.82], n = 52, P < 0.01). Neither dGEMRIC nor dQCTA correlated with arthroscopic grading. dGEMRICIV and non-normalized dGEMRICIA were not related while ΔR1,IV correlated with normalized ΔR1,IA (rs = 0.52 [0.28–0.70], n = 50, P < 0.01).ConclusionsThis study suggests that dQCTA is in best agreement with dGEMRICIV at 45 min after CT contrast agent injection. dQCTA and dGEMRIC were not related to arthroscopy, probably because the remaining cartilage is analysed in dGEMRIC and dQCTA, whereas in arthroscopy the absence of cartilage defines the grading. The findings indicate the importance to take into account the contrast agent concentration in SF in dQCTA and dGEMRICIA.