[Computer tomographic densitometry of human blood. The effect of absorption by parenchymatous organs and effusions (author's transl)].

In vitro measurements of human blood with varying haemoglobin and plasma concentrations have shown a linear relationship between haemoglobin concentrations and attenuation values. A change of haemoglobin content of 1 g/100 ml. blood produced and equivalent density change of 1.5 HU. Attenuation of normal blood is between 55 to 75 HU, that of plasma about 33 HU. Transudates with a protein concentration of less than 5 g/100 ml. show an attenuation value of less than 26 HU. It is therefore possible to indicate the presence of effusions by computer tomography. The effect of the composition of the blood on the attenuation produced by parenchymatous organs is discussed. It is concluded that attenuation values of organs is not seriously affected by even severe haematological changes.