CT of swollen legs.

The use of a single axial slice through the mid calf in the differential diagnosis of a swollen leg is described. This is a very simple quick non-invasive investigation. Venous obstruction results in an increase in the cross sectional area of the muscle compartment. The subcutaneous fat layer is normally homogeneous; in obesity or lipoedema it is increased but remains homogeneous. In lymphoedema fluid collects in the interstitial spaces which become very prominent on CT images. In chronic lymphoedema a honeycomb pattern is seen as a result of increase in the interstitial tissue due to fibrosis. Popliteal cyst extensions result in fluid collections between muscle planes. Haematomas have higher attenuation, and are intramuscular. The findings in 64 patients and 10 controls are presented and the literature is reviewed.