Apparent Diffusion Coefficient
Pronunciation: A-D-C
Also written as: ADC — Apparent Diffusion Coefficient
Quantitative parameter measuring water molecule diffusion restriction in diffusion-weighted imaging.
Full Definition
The Apparent Diffusion Coefficient is a quantitative measure derived from diffusion-weighted MRI that reflects the microscopic mobility of water molecules in tissue. In oncologic imaging, ADC values help characterize tissue cellularity, with lower values typically indicating higher cellular density as seen in malignant tumors. ADC mapping is particularly valuable for differentiating benign from malignant lesions, monitoring treatment response, and detecting tumor recurrence, as successful treatment often results in increased ADC values due to decreased cellular density.
Usage
Usage note: Report ADC values with appropriate units (typically × 10⁻³ mm²/s).
In Context
- "The ADC map demonstrated restricted diffusion within the enhancing lesion, consistent with malignancy." — MRI report
- "Post-treatment ADC values increased significantly, indicating successful tumor response." — Follow-up imaging