The Pulsatility Index (PI) is a key metric in vascular ultrasound, quantifying the degree of pulsatility in blood flow. It’s calculated as the peak systolic velocity minus the end diastolic velocity, divided by the mean velocity. A higher PI indicates more pulsatile flow, often seen in arteries with less resistance downstream, while a lower PI suggests reduced pulsatility, which can be indicative of increased distal resistance or stenosis.
This measurement is crucial for diagnosing various vascular conditions, including peripheral artery disease, renal artery stenosis, and assessing fetal well-being in obstetric ultrasound. Sonographers and clinicians utilize the pulsatility index to evaluate circulatory health, guide treatment decisions, and monitor patient response to interventions, making it an indispensable tool in medical ultrasound diagnostics.