Purpose: To use qualitative lymphangioscintigraphy (LAS) findings to differentiate leg edema caused by high and low output lymphatic failure.
Methods: LAS was performed in legs with secondary lymphedema (LE), i.e., low output failure (N = 79), and functional venous insufficiency (FVI), i.e., high output failure (N = 56), and normal legs (N = 26). Whole body images were obtained, 15, 60, and 180 min after technetium-99m injection. The rate and timing of visualization of lymphatic structures, washout out of tracer, and presence of dermal backflow were assessed.
Results: The most significant finding for differentiating LE from other conditions was not the visualization of lymphatic structures, but the washout of the tracer from the leg trunk (LE 27%, FVI 100%, normal leg 100%, P <.0001). On the other hand, the most significant finding for differentiating FVI from other legs was the visualization of inguinal lymph nodes at 15 min (LE 11%, FVI 82%, normal leg 8%, P <.0001).
Conclusions: We found that the lack of washout from the leg trunk was most suggestive of a low output status of the lymphatic system, while earlier visualization of inguinal lymph nodes was suggestive of a high output status.
Keywords: leg; lymphangioscintigraphy; lymphedema; venous insufficiency.