Factorial analysis in radionuclide lymphography: assessment of the effects of sequential pneumatic compression

The effects of intermittent pneumatic compression (IPC) in 12 patients with lower or upper limb lymphedema were studied using a computer-based technique (factorial analysis) of dynamic lymphoscintigraphy. After subcutaneous injection of radiocolloid into the first interdigital web space of the arm or leg, scintigraphic recordings consisted of 40 consecutive one-minute frames of both lower extremities or an edematous upper extremity. Pneumatic compression by Euroduc (6 patients) or by Lymphapress (6 patients) was applied during the final 20 minutes of the recording. A three factors factorial analysis (FA) was performed successively for each extremity. FA allowed "uncontaminated" curves to be displayed distinct from neighboring structures and corresponded to dynamic tracer activity in the interstitium, at the injection site, and within lymphatic vessels. Based on the results of lymphatic vascular factorial analysis, a beneficial effect of IPC was detected in 18 of 22 limbs examined. FA processing suggested that IPC facilitated radiocolloid transport in the proximal portion of the limb and also propelled tracer from the injection site toward the lymphatics. The effect of IPC was evident as soon as external compression therapy began and was similar with either mechanical unit. Residual tracer activity in peripheral lymphatics 20 minutes after application of IPC was higher in the edematous as compared with the normal limbs. FA processing is a new and potentially valuable method to evaluate the effects of external pneumatic compression in the management of peripheral lymphedema.