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.