An ultrasonic diagnostic imaging system and method acquire a sequence of image data as a bolus of contrast agent washes into and out of the liver. The image data of contrast intensity is used to compute time-intensity curves of contrast flow in the hepatic artery, the portal vein, and at one or more regions of interest in the liver. The time-intensity curve of contrast flow in the hepatic artery is scaled to the time-intensity curve of contrast flow in a region of interest to produce time-intensity curve data representing the flow of blood at the region of interest due to arterial flow. The time-intensity curve data representing the flow of blood at the region of interest due to arterial flow is subtracted from the time-intensity curve of contrast flow in the region of interest to produce time-intensity curve data representing the flow of blood at the region of interest due to venous flow.
