Assessment of Correlation between Intravoxel Incoherent Motion Diffusion Weighted MR Imaging and Dynamic Contrast-Enhanced MR Imaging of Sacroiliitis with Ankylosing Spondylitis

Figure 1

Intravoxel Incoherent Motion (IVIM) Diffusion Weighted MR imaging (DWI) in a 16-year-old male patient with duration of 3-year diagnosed ankylosing spondylitis (AS). On the Ds (pure molecular diffusion) map, (perfusion fraction) map, and Df (perfusion-related diffusion) map, ROIs are placed in the juxta-articular bone marrow with sacroiliitis of AS. IVIM diffusion decay curves were shown with increasing values (0, 10, 20, 30, 50, 80, 100 120, 200, 700, and 800 s/mm²) based on monoexponential model (blue line) and biexponential model (red line) (Ds: 0.04 ×10⁻³ mm²/s, : 0.12, Df: 19.97 × 10⁻³ mm²/s). The combination of their log plots of SI versus -value (the curves from top to bottom within < 200 s/mm²) IVIM DWI signal intensity decay shows a nonlinear relation for the ROI.