The Visible Lymphatic Vessels of the Lower Extremities: A Preliminary Study by Contrast Ultrasonography.

Abstract

Objectives: Lymphoscintigraphy is standard diagnostic imaging for the limbs of patients with lymphedema and also a good modality for functional assessment of lymph flow. However, this modality cannot reveal individual lymphatic vessels that are candidates for lymphaticovenous anastomosis. We report a preliminary study to detect the lymphatic vessel and to observe its flow in real time in the lower extremities of healthy volunteers with contrast-enhanced ultrasonography (ce-USG). Methods: The lymphatic vessels of the lower extremities (10 limbs) of 10 healthy volunteers were examined. They were all female, and the mean age was 42.5 years. First, indocyanine green fluorescence lymphography was performed to mark the superficial lymphatic vessels. Next, the contrast agent perflubutane (Sonazoid) was injected into the dorsum, and lymphatic vessels were detected by ce-USG. To check the optimal condition of injection, the point of it changed 1, 2, and 4 points, and the volume in total changed 0.1, 0.2, and 0.8 mL. The lymphatic flow under manual lymph drainage was investigated. Results: There is no remarkable side effect in this study. The lymphatic vessels were visible in all cases when the contrast agent injected was 0.8 mL and according to the line marked by indocyanine green fluorescence lymphography. They run superficial in the subcutaneous area from dorsum to groin continuously. Most of them were around the great saphenous vein (Fig). No perforated lymphatic vessel through the fascia was observed. In the inguinal region, some lymphatic vessels come into the lymphatic node, and the internal side of the lymphatic node was enhanced clearly. We could detect more lymphatic vessels depending on the injected points. During manual lymph drainage, they were enhanced clearly according to the rhythm of drainage. Conclusions: The study shows that ce-USG could be a useful diagnostic modality to clearly detect normal lymphatic vessels and to evaluate functional flow in real-time fashion in the normal limbs. In lymphaticovenous anastomosis treatment for lymphedema in selected patients, it is important to detect functional lymph vessels for the long-term patency and decreasing volume of diseased limb. The lymphatic flow in lymphedema patients was sometimes changed from superficial dominant to deep dominant. Further study to investigate the relation between superficial lymphatic flow and deep lymphatic flow is necessary in patients with lymphedema.