Radionuclide lymphoscintigraphy in limb edemas

Indirect radionuclide lymphoscintigraphy is a safe, non-invasive and physiological method for the assessment of the limb lymphatic system. Colloids as antimony or rhenium sulphide labeled with 99m technetium have been widely used for morphological studies. Quantitative studies involving a continuous count rate monitoring of the injection sites followed by a computer analysis of dynamic image sequences have been a new promising step for an objective measurement of the peripheral lymphatic function. The injection site is always bilateral on the first web space of either the hand or the foot using a small volume (<0.2 mL) of the radiocolloid. This method has been validated on 30 young healthy volunteers and normal values established from a group of 125 upper and 141 lower limbs (normal subjects). The normal results showed a slight but continuous decrease in lymphatic function depending on the age of the subject. In pathological situations, we observed dysfunction of the lymphatic system in pure lymphoedemas or so-called lympho-venous edemas as demonstrated on the 1,182 upper and 2,463 lower limbs tested. The radionuclide lymphoscintigraphy may be helpful in cases of unilateral swollen limbs demonstrating a lymphatic dysfunction on a clinically normal contralateral limb at the first stage of a distal edema which appears within a few weeks or days, in a transient edema phase when normal status and oedema alternate. The lymphoscintigraphy gives objective and reproducible parameters necessary to assess the lymphatic variation under therapy (decongestive physiotherapy, surgery, drugs) and may be useful in the selection of new lympho-tonic treatments. This method is only reflecting the lymphatic function and is unable to appreciate the total lymphatic flow of the limb. Its results only reflect what happens at the injection site and it may be necessary to add a second test using a proximal injection in order to assess the occurrence of lymph nodes not visualized by the general method. (authors)