CT-Scanning

Plain radiographs may show calcification in the abdomen and even in the bowel, but it is more clearly seen on CT scanning. Although ultrasonography will provide most of the information which can be obtained from CT, there is a characteristic appearance on a CT scan. There will be low-density, rapidly enhancing periportal areas, uniformly distributed throughout the liver. During a contrast examination, the low-density zones usually become hyperdense, but some will be isodense with the liver. In transverse section these low-density periportal areas are rounded, but in longitudinal section the pattern follows the portal vein and can be linear and occasionally branching. This is best seen in the central area of the liver because towards the periphery the veins are too small to be clearly demonstrated. It has been suggested that the rapid enhancement is due to the multiple small periductal vascular collaterals. It is also possible that there is increased hepatic artery circulation, particularly around small or medium obstructed portal veins, and this contributes to the enhancement. It has been described as angiomatous but this is perhaps somewhat misleading. As the fibrosis progresses, there is scarring and the periportal zones become less vascular. (The pattern in schistosomiasis japonica is different.) Measurement of the size of the hepatic and portal circulations may be used to grade the severity of the cirrhosis, but this is more commonly done with ultrasound, aided by Doppler flow studies.

As already noted, CT can demonstrate the calcified eggs in the colon and rectum, and in the surrounding soft tissues. This does not have any clinical significance, apart from aiding in the diagnosis of schistosomiasis.

Isotope scanning

Isotope scintigraphy early in the disease shows a normal to moderately enlarged liver with either homogeneous or slightly mottled radioactive tracer uptake. There is a mottled pattern resembling that seen in Laënnec's cirrhosis and generally reflecting the extent of the liver damage. An enlarged spleen can also be visualized.