diffusion restriction
Reduced water molecule movement appearing as high signal on DWI with corresponding low ADC values.
Full Definition
Diffusion restriction refers to the reduced random motion of water molecules in tissue, typically due to cytotoxic edema, high cellularity, or viscous fluid. On diffusion-weighted imaging, restricted diffusion appears as hyperintense signal that persists on high b-value images and corresponds to reduced apparent diffusion coefficient (ADC) values. This finding is characteristic of acute stroke, abscess contents, tumors with high cellularity, and certain inflammatory conditions. True diffusion restriction must be confirmed by correlating DWI hyperintensity with low ADC values to exclude T2 shine-through effects.
Usage
Usage note: Must correlate DWI hyperintensity with low ADC values for confirmation.
In Context
- "Acute diffusion restriction in the left insular cortex was consistent with recent ischemic stroke." — emergency stroke protocol
- "The rim of diffusion restriction around the lesion suggested an active inflammatory process." — brain abscess evaluation