The Value of the T2-Weighted Multipoint Dixon Sequence in MRI of Sacroiliac Joints for the Diagnosis of Active and Chronic Sacroiliitis.

OBJECTIVE: The objective of this study was to determine the value of the T2-weighted multipoint Dixon technique as a single sequence in MRI of the sacroiliac joints for the diagnosis of active and chronic sacroiliitis.

SUBJECTS AND METHODS: The T2-weighted multipoint Dixon sequence with water-only, in-phase, opposed-phase, and fat-only images was added to a routine MRI protocol, which included T1-weighted, fat-saturated T2-weighted, and contrast-enhanced fat-saturated T1-weighted sequences, for imaging 73 patients. Images obtained as part of the routine protocol were reviewed first by two radiologists. Then, the T2-weighted multipoint Dixon images were reviewed separately. Signs of active inflammation detected on fat-saturated T2-weighted and contrast-enhanced fat-saturated T1-weighted images were compared with the water-only images. Signs of chronic sacroiliitis detected on T1-weighted images were compared with the fat-only, in-phase, and opposed-phase images. Contrast-to-noise ratios (CNRs) of all lesions were statistically analyzed. ANOVA and posthoc Tukey tests were used to compare CNR data.

RESULTS: The mean CNR of 34 lesions with bone marrow edema or osteitis was greater on the water-only images (CNR, 176) than on the fat-saturated T2-weighted images (CNR, 82) and the contrast-enhanced fat-saturated T1-weighted images (CNR, 56), and this difference in mean CNRs was statistically significant (p < 0.01). There were also statistically significant differences in CNRs between sequences (p < 0.01). The highest mean CNR for subchondral sclerosis in 23 lesions was noted on in-phase images, and the highest mean CNR for periarticular fat deposition in 29 lesions was noted on opposed-phase images. Qualitative analyses also revealed that T2-weighted multipoint Dixon images were superior in showing signs of both active and chronic sacroiliitis.

CONCLUSION: The T2-weighted multipoint Dixon sequence is superior to conventional MRI sequences in depicting diagnostic signs of active and chronic sacroiliitis and therefore may be used as a single sequence.