Figure 2: Doppler ultrasound. (a) Graft of the patient shows the absence of blood flow at the level of the renal cortex, arcuate arteries, interlobular arteries, and arterial anastomosis. (b) Duplex mode shows an arterial biphasic waveform with delayed acceleration, decreased systolic peak, and increased flow in diastole, which is a suggestive pattern of ischemia.