Reduced visualization of cerebral infarction on diffusion-weighted images with short diffusion times.

Abstract

Diffusion-weighted imaging (DWI) is a useful tool for early detection of cerebral infarction. However, recent reports have demonstrated that DWI with short effective diffusion time (∆eff) can obscure visualization of infarction. We report three cases, including four acute-to-subacute infarctions, that demonstrated reduced visualization of the infarctions on DWI with shorter ∆eff. DWI was performed with different ∆eff: short and long ∆eff, using oscillating gradient spin-echo (OGSE) DWI, and intermediate ∆eff, using pulsed gradient spin-echo (PGSE) DWI. Different apparent diffusion coefficient values (due to different ∆eff) were also observed; these were considered to be the underlying causes of the under-evaluation of infarctions on DWI. The DWI with shorter ∆eff may obscure infarction. High-performance magnetic resonance imaging scanners with higher maximal gradient strength (Gmax) can perform DWI with shorter ∆eff than scanners with lower Gmax. Therefore, the appropriate ∆eff should be set for the detection of restricted diffusion.