[Radiopaque hemithorax, with special reference to scintigraphic methods]

Radioopaque hemithorax is frequently observed. The various situations in which it may occur are examined aetiopathologically, along with the general and specifically radiological methods used for its investigation. Particular attention is given to the employment of radio-isotopes for this purpose and the methods involved. Results obtained with perfusion are noteworthy, and even more so those achieved with positive tracers such as 67Ga citrate and 57Co Blm, especially in the differential diagnosis of pleural effusion and mesothelioma through what is described as the "paradox effect".