T2 Mapping of the Sacroiliac Joints at 1.5 T can Identify Patients with Spondyloarthritis

Purpose: To determine whether T2 relaxation time measurements of the sacroiliac joints (SIJs) might help identify patients with spondyloarthritis.

Methods and Materials: Twenty-one biologic-naive patients with axial spondyloarthritis (10 men, 11 women; mean age: 43 ± 12 years [range: 19–57 years]) and 21 healthy volunteers (14 men, 7 women; mean age: 34 ± 10 years [range: 28–71 years]) underwent standard unenhanced magnetic resonance imaging (MRI) of the SIJs (T1-weighed, T2-weighted, short tau inversion recovery images; 1.5-T MRI unit) including an oblique axial multislice multiecho spin-echo sequence. A senior radiologist reviewed standard MRI sequences to assess the SIJs according to the Assessment of SpondyloArthritis International Society (ASAS) criteria and SPondyloArthritis Research Consortium of Canada (SPARCC) MRI index. T2 maps obtained from multiecho sequences were used to manually draw a total of 594 regions of interests in the cartilaginous part of the SIJs by two radiologists using dedicated software. Bland-Altman method, Mann-Whitney U, Pearson’s correlation coefficient, and chi-square statistics were used.

Results: Patients and controls were not different in terms of age (p = 0.062) and sex (p = 0.350) distribution. ASAS criteria were positive for sacroiliitis in 6 of 21 patients (29%). Nine patients (43%) were HLA-B27 positive. Interobserver reproducibility of T2 relaxation time was 88% (coefficient of repeatability: 5.9; bias: 0.96; p < 0.001). The mean T2 values of patients (59.2 ± 2.9 ms; range: 54.3–66.3 ms) was significantly higher (p < 0.001) than that of healthy controls (39.6 ± 3.4 ms, range: 33.6–46.6 ms). Receiver operating characteristic curve analysis revealed that a T2 value of 50.5 ms yielded 100% sensitivity and 100% specificity to differentiate patients from controls. No association or correlation was found between T2 relaxation time measurements and SPARCC score (r = 0.032; p = 0.891), ASAS criteria (p = 0.622), HLA-B27 positivity (p = 0.917), age (r = − 0.038; p = 0.871), and sex (p = 0.197).

Conclusion: T2 relaxation time measurements of the SIJs might help identify patients with axial spondyloarthritis and negative standard MRI.

No conflict of interest has been declared by the author(s).