Magnetic resonance venography of the lower limb.

Prior to surgery or endovascular therapy for the lower extremity varicose veins or deep venous thrombosis (DVT), ultrasonography provides useful information. But it depends on the operator's technique, each image is limited to a small field of view and interpretation may be subjective. On the other hand, magnetic resonance (MR) imaging is now available with several postprocessing techniques using workstations to demonstrate the gross and objective morphology of these lesions less invasively than the conventional ascending venography. As non-contrast MR venography, fat suppressed three-dimensional (3D) coronal balanced turbo field echo (bTFE) is mainly applied in the semisupine position. The varicose veins on the muscle fascia are easily recognized on volume rendering and the perforating veins can be identified on maximum intensity projection (MIP) and axial multiplanar reconstructions. Gadolinium-enhanced fluid attenuated inversion recovery-bTFE is added when coexisting joint effusion or edema masks the veins. For DVT, direct thrombus imaging (DTI) using fat suppressed 3D coronal inversion recovery-prepared blood suppressed gradient echo sequence is applied. However, the signal intensity of DVT depends on the clot's age on DTI and is sometimes confusing on bTFE. After gadolinium administration, blood shows higher signal intensity than clots regardless of the age and DVT can be easily depicted as filling defects on the axial reformations and summarized on the soap bubble-MIP.