趙啟明醫生醫務所         Dr Leo Chiu, Central Vascular Clinic 

(Non-invasive studies) Echoes from high-frequency ultrasound are analysed and processed to show the contour and reveal narrowing or blockage of the artery. The Doppler shift of ultrasound wave is also used to estimate the velocity of blood flow inside the vessel. How is duplex scan performed Water-based gel will be placed along the legs. The ultrasound probe will be placed in the gel to display a segment of the vessel. The probe is moved slowly up and down the vessels to examine the whole system. The limb may be repositioned to allow a better view of the vessels. The direction and velocity of blood flow inside any specific segment of a vessel is interrogated to assess the severity of the narrowing and direction of flow. ► Back to top