Optimizing Doppler and color flow US: Application to hepatic sonography

In the imaging of patients with chronic liver disease or portal hypertension or who have undergone liver transplantation or surgery, accurate evaluation of the hepatic vasculature is usually necessary. Because Doppler ultrasonography (US) is capable of accurately characterizing the nature of flow within the major hepatic arteries and the portal and hepatic veins, it is widely used for imaging the liver vasculature. An informed choice of transducer and scanning techniques is important in the evaluation of the liver vasculature. In addition, there are a variety of operator-dependent technical parameters (eg, baseline, frame rate, wall filters, gain, velocity range, angle correction, gate size and position) that must be optimized when performing Doppler US of the liver. Changes in these parameters independently influence both the color and spectral components of the Doppler US examination; therefore, the parameters should be optimized separately for each patient. Failure to appropriately adjust these parameters may result in artifacts or misinterpretation of the study, which will frequently affect patient treatment. In contrast, knowledge of these operator-dependent parameters will permit optimization of the study and improve the overall utility of liver Doppler US.