Lymphedema Test To confirm a diagnosis of lymphedema, your physician may order tests, including one or more of the following: • Lymphoscintigraphy, which uses a low-dose injected radioactive substance to trace the flow of lymph fluid through your lymphatic vessels • Magnetic resonance imaging (MRI), which uses radiowaves and magnetic fields to detect patterns in your internal tissues that are characteristic of lymphedema • Computed tomography (CT) scanning, which creates images of your internal tissues from a series of cross-sectional x-ray • Duplex ultrasound, which uses high-frequency sound waves and Doppler technology to show vessels and real-time blood flow on a screen to rule out a blood clot in your leg • Lymphangiography, which uses contrast (dye) directly injected into the lymphatic vessels, is now used less frequently Source: http://www.vascularweb.org/_CONTRIBUTION_PAGES/Patient_Information/Nor thPoint/Lymphedema.html