Final answer:
The statement regarding graft entrapment is false; there should normally be detectable blood flow in a Doppler ultrasonic image, regardless of the knee being bent or straight. Graft entrapment would not eliminate color flow or Doppler signal when the knee is bent under normal circumstances.
Step-by-step explanation:
The statement "With Graft Entrapment, normal flow is obtained when the knee is straight. When the knee is bent no color flow and no Doppler signal is detected" is false. Graft entrapment is a condition where the expected blood flow pattern is disrupted due to the graft being compressed. Normally, the Doppler ultrasonic imaging would show continuous blood flow regardless of the knee's position. The color Doppler image referenced, using colors to show velocity (with the highest velocities in red and the lowest in blue), would still reveal some amount of flow even in compromised conditions.
In the case of a partiually occluded artery, as shown in the Doppler-shifted ultrasonic images, the blood flows quicker through a constriction to maintain flow. Disruption in color and Doppler signals with knee flexion suggests the graft is being pinched or obstructed, which is abnormal and typically signifies an issue like entrapment or kinking of the graft, but does not mean that no color flow or Doppler signal would normally be detected when the knee is bent.