Arterial resistivity index

Arterial resistivity index
Arterial resistivity index (right) from retinal laser Doppler imaging (left).
Purpose	measure of pulsatile blood flow

The arterial resistivity index (also called as Resistance index, abbreviated as RI), developed by Léandre Pourcelot [1], is a measure of pulsatile blood flow that reflects the resistance to blood flow caused by microvascular bed distal to the site of measurement. It is primarily used in ultrasound imaging to evaluate arteries and solid organ damage.