Which MRI sequence is most sensitive for diffuse axonal injury?

Which MRI sequence is most sensitive for diffuse axonal injury?

• A. T1 weighted
• B. FLAIR
• C. Diffusion weighted imaging
• D. Susceptibility-weighted imaging

Answer: (D)

Diffuse axonal injury is driven by shearing forces that leave tiny hemorrhages in white matter. These microhemorrhages are often too small for standard MRI sequences to show, but susceptibility-weighted imaging is specifically designed to pick up small blood products by exploiting magnetic susceptibility differences. Because SWI is highly sensitive to hemosiderin and deoxyhemoglobin, it detects more microbleeds at gray–white matter junctions, the corpus callosum, and brainstem where DAI lesions concentrate, making it the most sensitive sequence for identifying DAI. Other sequences like T1, FLAIR, and diffusion-weighted imaging may reveal other injury aspects but are less reliable for these microhemorrhages; DWI can show diffusion abnormalities but not as consistently microhemorrhages. Thus SWI best reveals DAI.

Diffuse axonal injury is driven by shearing forces that leave tiny hemorrhages in white matter. These microhemorrhages are often too small for standard MRI sequences to show, but susceptibility-weighted imaging is specifically designed to pick up small blood products by exploiting magnetic susceptibility differences. Because SWI is highly sensitive to hemosiderin and deoxyhemoglobin, it detects more microbleeds at gray–white matter junctions, the corpus callosum, and brainstem where DAI lesions concentrate, making it the most sensitive sequence for identifying DAI. Other sequences like T1, FLAIR, and diffusion-weighted imaging may reveal other injury aspects but are less reliable for these microhemorrhages; DWI can show diffusion abnormalities but not as consistently microhemorrhages. Thus SWI best reveals DAI.