An information-based comparison of diffusion attenuation models in normal and inflamed bone marrow

Area of Science:

• Radiology
• Medical Imaging
• Biophysics

Background:

• Diffusion-weighted imaging (DWI) is used to characterize bone marrow edema in inflammatory diseases.
• Understanding diffusion signal behavior is crucial for optimizing DWI protocols.
• The best model for describing diffusion attenuation in bone marrow edema is currently unknown.

Purpose of the Study:

• To determine which of three diffusion attenuation models best describes signals from normal and inflamed bone marrow.
• To compare monoexponential, intravoxel incoherent motion (IVIM), and kurtosis models.
• To identify the optimal model for robust and clinically useful DWI in immune-mediated inflammatory diseases.

Main Methods:

• Diffusion-weighted imaging of sacroiliac joints was performed on 11 patients with active spondyloarthritis and 17 controls.
• B-values ranged from 0 to 600 s/mm².
• Monoexponential, IVIM, and kurtosis models were fitted to signals from bone marrow edema and normal marrow regions.

Main Results:

• The IVIM model provided the best signal description across normal and inflamed bone marrow (0-600 s/mm²).
• IVIM excelled in normal marrow, capturing fast diffusion components.
• In bone marrow edema, IVIM and kurtosis effects diminished, approaching monoexponential behavior.

Conclusions:

• The IVIM model is superior for characterizing bone marrow diffusion signals in spondyloarthritis.
• Increased Dtissue within the IVIM framework may explain the near-monoexponential behavior in edematous bone.
• Findings support IVIM model's utility for optimizing DWI protocols in inflammatory bone marrow conditions.