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Hepatic arterial resistive index

Last revised by Dr Jeremy Jones on 20 Sep 2021

The resistive index (RI) is the most common Doppler parameter used for hepatic arterial evaluation. The usual range in normal, as well as post-transplant individuals, is between 0.55 and 0.8.

It is measured by:

Resistive index (RI) = (peak systolic velocity - end-diastolic velocity)/peak systolic velocity

Hepatic arterial resistive index is most often assessed during the evaluation of a liver transplant.  In this setting, a low RI is usually more specific for disease than a high RI (the opposite situation from a renal transplant) 5.

Low RI: more specific for disease in a liver transplant, a low RI may result from:

High RI: less specific for disease in a liver transplant, a high RI may result from:

  • microvascular compression or disease
    • chronic hepatocellular disease
    • transplant rejection
    • hepatic venous congestion
      • chronic congestive hepatopathy
    • nonocclusive hepatic artery hypoperfusion syndrome 8
  • physiologic
    • postprandial state
    • advanced patient age
    • may transiently elevate within 72 hours after transplant 

A high RI can be classified into four types 4:

  • type I: RI >0.80 with continuous blood flow in the diastolic phase
  • type II: RI = 1, complete absence of the diastolic signal and preserved systolic velocity
  • type III: absence of diastolic signal and diminished systolic velocity
  • type IV: undetectable Doppler flow

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