Which of the following describes the role of duplex imaging after vascular grafts for surveillance?

• A. Duplex imaging is not used for graft surveillance.
• B. Duplex can assess flow velocity and patency to monitor grafts.
• C. Duplex replaces CT angiography for all endoleak types.
• D. Duplex cannot detect changes in flow.

Answer: (B)

Duplex imaging monitors vascular grafts by measuring blood flow velocity and evaluating the flow patterns through the graft and at the anastomoses. By tracking these velocities and waveforms over time, you can detect developing stenosis or occlusion, confirming whether the graft remains patent. This noninvasive, repeatable test provides real-time hemodynamic information, making it ideal for serial surveillance after graft placement. It can also raise suspicion for abnormal flow such as endoleaks after endovascular repairs, but it does not replace CT angiography for all endoleak types, since some scenarios require cross-sectional imaging for complete characterization.