Radioisotope Scanning of the Liver and Spleen in Dextrocardia and in Situs Inversus with Levocardia.

KNOWLEDGE of the position of the abdominal organs is important in cardiac diagnosis. Thus a mirror-image dextrocardia is usually observed in a patient with complete situs inversus; this condition more frequently occurs in an otherwise normal individual than in one with a malformed heart. By contrast, when dextrocardia occurs without situs inversus, malformation of the heart is the rule. When the heart occupies its normal position but situs inversus of the viscera is present, the heart is almost always seriously malformed. Partial situs inversus is now known to be relatively common in patients with dextrocardia and severe multiple intracardiac defects and is occasionally seen in patients with levocardia. The term "visceral heterotaxy"1 has been used to denote partial situs inversus with a midline cecum or a symmetrical liver and is common in association with asplenia.2 Asplenia, although rare, is usually associated with severe cardiac malformations. Accurate localization of the liver may be difficult, especially if its lobulation is unusual or its contour symmetrical. Although the spleen when present uniformly lies on the same side as the stomach, the diagnosis of asplenia is uncertain. An ancillary method for the demonstration of the position of the liver and spleen appeared desirable. Radioisotope scanning of the liver was first described by Friedell et al.3 The basic principle of this method is the visualization of the