restricted diffusion
Impaired water molecule movement appearing bright on DWI and dark on ADC maps, indicating cellular injury.
Full Definition
Restricted diffusion refers to the impaired movement of water molecules within tissue, appearing as hyperintense signal on diffusion-weighted imaging (DWI) with corresponding hypointense signal on apparent diffusion coefficient (ADC) maps. This finding typically indicates cytotoxic edema from cellular injury, most commonly seen in acute ischemic stroke within the first few hours. Other causes include seizures, hypoglycemia, cellular tumors, abscess formation, and certain types of encephalitis. The degree and pattern of restriction can provide important diagnostic and prognostic information. Unlike T2 shine-through artifact, true restricted diffusion shows low ADC values.
Usage
Usage note: Always correlate DWI hyperintensity with ADC values to confirm true restriction.
In Context
- "Acute restricted diffusion was identified in the left MCA territory consistent with stroke." — Emergency DWI report
- "The lesion showed restricted diffusion with low ADC values suggesting high cellularity." — Brain tumor evaluation