Comparison of 2D Thin Section Dixon, 3D Isotropic SPACE, and 2D T2-Weighted Sequences in Ankle MRI

Abstract

Purpose: This study aimed to conduct a comparison between 2D thin section intermediate- weighted Dixon turbo spin echo (TSE), 3D intermediate-weighted SPACE (sampling perfection with application-optimized contrasts using flip angle evolutions) TSE, and 2D fat-suppressed T2-weighted TSE in terms of their image quality and diagnostic performance for ankle ligament evaluation. Materials and Methods: Thirty-eight ankle MRI studies were retrospectively analyzed. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the multiplanar reformation images of the sequences were obtained. For each sequence, the subjective image quality and the diagnostic performance for ankle ligament tear were analyzed. Results: The Dixon demonstrated the highest CNR both between ligament and fluid and between ligament and bone marrow. The 3D SPACE showed the highest SNR of the ligament. Regarding subjective image quality, it was significantly higher in the T2-weighted image than it was in the SPACE (p < 0.05), while there was no significant difference between the Dixon and the SPACE. The Dixon showed the highest sensitivity for anterior talofibular ligament (ATFL) tear (80.0%; 95% confidence interval [CI], 64.4–92.3) and deep deltoid ligament (DL) tear (86.4%; 95% CI, 65.1–97.1), and it showed the highest specificity for ATFL tear (70.2%; 95% CI, 59.3–79.7). The interobserver agreement was moderate to good (intraclass correlation coefficient [ICC], 0.50–0.93) in most cases except for the SNR of deep DL (ICC of 0.35–0.62). Conclusion: For ankle ligament evaluation, the 2D thin section Dixon provides adequate image quality with high SNR and CNR and the highest sensitivity for detecting tears.