Doppler ultrasound

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Resistive Index
Normal Doppler

Nonresistive Vessels - high diastolic component for organs that need constant perfusion, internal carotid, hepatic and renal arteries.

Resistive Vessels - litttle to reversed flow in diastole for organs that do not need constant perfusion, external carotid, iliac and brachial arteries.

Resistive Index - compares peak systole to minimum diastole (see diagram).

Transplant Liver

Hepatic artery stenosis - parvus trades waveform or velocity > 200 cm/s

Portal vein stenosis - narrowing < 2.5 cm or velocity > 150 cm/s at anastomoses

Hepatic vein stenosis - flattening of the normal triphasic waveform