How do areas affected by a subacute stroke appear on DWI and ADC maps?

In the context of imaging in subacute stroke, diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps provide vital information regarding the status of the affected brain tissue. In the subacute phase, which typically spans from approximately 3 days to around one week post-stroke, areas of the brain that have been affected by ischemia typically manifest as bright regions on DWI due to restricted diffusion of water molecules in the affected tissue, indicative of cytotoxic edema resulting from cellular injury.

On ADC maps corresponding to this stage, the affected areas appear moderately bright. This can be attributed to the diffusion of water being somewhat impaired but not to the extent seen in hyperacute strokes. The natural evolution of the stroke process leads to changes in tissue properties, where the ADC values might start to recover slightly compared to the hyperacute phase. Therefore, describing the appearance of these regions as bright on DWI and moderately bright on ADC effectively captures the typical character of a subacute stroke.

This understanding is critical for radiologists and medical practitioners interpreting MRI scans, as it assists in correlating imaging findings with clinical symptoms and timing of the stroke, which is essential for appropriate management and intervention strategies.