Prediction of human spleen size by computer analysis of splenic scintigrams

A method of assessing spleen size from splenic scintigraphs obtained using autologous heat damaged "Tc m labelled red cells is described. The method depends on a "computed volume" estimate. The method has a correlation coefficient of 0-989 with the exsanguinated weight of the spleen after splenectomy and has been shown to have an accuracy superior to methods previously described. The involvement of the spleen in human disease is poorly understood and descriptions of changes in the spleen are usually based on those found in morbid anatomical or surgical specimens. Dynamic changes in specific functions such as red-cell destruction can be observed but probably reflect red-cell abnormalities rather than changes in the spleen. In many disease states there is a need to be able to monitor changes, especially in spleen size, in relation to the course of the disease. Changes in spleen size in animals have been reported in association with immunological phenomena (Congdon and Makinodan, 1961; Old et al., 1961; Simonsen, 1961). Accurate monitoring of spleen size in man would allow observations of dynamic changes in relation to an immunological stimulus or in diseases which may have an immunological component. Clinical examination can monitor changes in truly massive splenomegaly but in general, spleens have to be larger than 750 g before half of them are palpated (Fischer and Leon, 1969). To detect lesser degrees of splenic enlargement an alternative method is required. Unfortunately, invariably many methods do not demonstrate the spleen. Radiography is successful in only 17 per cent of abdominal films (Rosenbaum, Leiber and Pellegrino, 1964) and although gas insufflation into the gastrointestinal tract or peritoneum can improve on this, invariably the spleen is not demonstrated (Zelman, 1958; Rosch, 1965). Radiographs taken at specific times during intravenous pyelography or coeliac arteriography (which is not without risk) can demonstrate the spleen so that its size can be assessed (Blendis, Williams and Kreel, 1969). However, Blendis made no comment as to the certainty with which the spleen could be demonstrated and the size was calculated from a single two-dimensional image of the organ.