Factorial analysis of dynamic lymphoscintigraphy in lower limb lymphoedema

The purpose of this work is to assess the contribution of factor analysis to the interpretation of dynamic lymphoscintigraphy. Twenty six adult patients with a lower limb lymphoedema and five control patients were studied. The technique involved a 3 mCi lymphovectoscint* 99Tcm-labelled ammonium sulphur colloid, bilateral pedal subcutaneous injection. Recording consisted of 40 consecutive 1-min frames of both legs followed by static pictures of each leg and pelvis at 40 min and 4 h after injection. The analysis of static pictures allowed a classification of patients into three groups: enhanced pattern, hypoplasia and dermic reflux. To evaluate better the different kinetic components of the sequential pictures, a factorial analysis (FA) software package was used. FA processing enabled the extraction from the dynamic series of different dynamic components, factorial curves and their associated factorial images which represent the anatomic structures with the same temporal behaviour. In each pattern the results of dynamic recording and of three FA factors were compared. FA provides an analytical temporal and spatial description of the dynamic sequence by extracting the different kinetic components; it yields a better differentiation of vessel and interstitium activity. It also provides some clues towards the understanding of oedema physiopathology and is of potential interest for the management of lymphoedema.