The importance of the subfascial lymphatics in the diagnosis of lower limb edema: investigations with semiquantitative lymphoscintigraphy.

A new method of semiquantitative lymphoscintigraphy for the evaluation of lower limb edema is characterized by (1) the evaluation of both the epifascial and subfascial system in order to assess type and stage of the edema, (2) the use of high-resolution digital whole-body imaging to facilitate the calculation of functional parameters, and (3) the use of active, standardized ergometry for reproducibility. The appearance time of 99mTc-labeled human albumin nanocolloid in inguinal lymph nodes after injection and the percent uptake of colloid into lymph nodes at 40 and 120 min after injection served as functional parameters. Patients with edema of the lower limb were compared with normal subjects. In patients with primary lymphedema the two lymphatic compartments are functionally compromised. Early and advanced stages of postthrombotic syndromes can be distinguished by characteristic lymphoscintigraphic patterns in epifascial and subfascial lymphatic compartments. These results indicate that only the separate evaluation of both the epifascial and subfascial compartments allows an accurate functional assessment of the lymphatics in lower limb edema.