Magnetic resonance image compilation sequence to quantitatively detect active sacroiliitis with axial...

To evaluate the diagnostic value of quantitative parameters [T1, T2, and proton density (PD) value] generated from magnetic resonance image compilation (MAGiC) sequence for active sacroiliitis in the patients with axial spondyloarthritis (ax-SpA).

A total of 90 consecutive ax-SpA patients were recruited and divided into an active group (n=48) and inactive group (n=42) based on the Spondyloarthritis Research Consortium Canada (SPARCC) score in this prospective study. In addition, 47 healthy volunteers were recruited as the control group. All participants underwent magnetic resonance (MR) scanning (including MAGiC sequence and T2 mapping sequence) to obtain the T1 value, T2 value, PD value of MAGiC sequence (MAGiC T1 value, T2 value, PD value), and the T2 value of T2 mapping sequence (T2 map T2 value). Intraclass correlation coefficients (ICC) were calculated to assess the inter‑ and intra‑observer agreement. The correlation between the MAGiC T2 value and the T2 map T2 value was analyzed using Spearman's Rho. One-way analysis of variance (ANOVA) and receiver operating characteristic (ROC) analysis were performed for all parameters.

For the active group, inactive group, and control group, the MAGiC T1 value, T2 value, PD value, and T2 map T2 value were (1,700.91±725.40, 546.58±59.49, 640.25±95.79 ms), (129.37±23.85, 117.16±20.37, 90.52±12.05 ms), (76.47±15.92, 82.69±9.51, 75.51±9.17 pu), and (96.75±16.06, 87.96±9.27, 82.03±10.17 ms), respectively. The difference of the MAGiC T1 value and the MAGiC T2 value in the three groups was statistically significant (P<0.05). The MAGiC PD value was only statistically significant between inactive and control groups (P=0.001). When comparing the ROC curves of quantitative values among the three groups, MAGiC T1 value showed higher diagnostic efficacy than MAGiC T2 value between the active and inactive groups (MAGiC T1_AUC: 0.971, MAGiC T2_AUC: 0.655, P<0.0001), and the MAGiC T2 value showed higher diagnostic efficacy than T2 map T2 value between the active group and control group, and the inactive group and control group (MAGiC T2_AUC: 0.940, T2 map T2_AUC: 0.784, P=0.0021; MAGiC T2_AUC: 0.877, T2 map T2_AUC: 0.644, P=0.0011). The consistency of measurements was excellent (ICC =0.972-0.998). The MAGiC T2 value was positively correlated with the T2 map T2 value, but with a low correlation (r=0.402; P<0.001).

A significant difference was detected between the MAGiC T1 and T2 values among the three groups, while MAGiC PD value had limited diagnostic value. MAGiC T1 value was better at differentiating the active group and inactive group than MAGiC T2 value. MAGiC T2 value was better at differentiating the active group and control group, the inactive group and control group than T2 map T2 value.