Imaging Diagnosis with Computed Tomography
The image obtained by X-ray computed tomography (CT) is a computer-assisted reconstruction of averaged X-ray attenuation in the individual pixel of the matrix. Therefore, CT reflects essentially the same information as the conventional X-ray photograph. The advantage and characteristics of CT are seen in better contrast resolution in a true tomogram. With the conventional film-screen system, a normal organ and its neoplasm show a similar X-ray attenu-ation and cannot be distinguished without the aid of contrast material. CT is capable of distin-guishing a 0.5% difference in contrast expressed in Hounsfield units or numbers (which are set at 0 for water and —1000 for air), whereas the conventional film-screen system can barely distinguish ascites from the liver (about 6% contrast).
KeywordsFatty Infiltration Focal Nodular Hyperplasia Cavernous Hemangioma Hypodense Area Arterioportal Shunt
Unable to display preview. Download preview PDF.
- 18.Otsuji H, Uchida H, Ohishi H (1983) Dynamic computed tomography of hepatocellular carcinoma with particular reference to capsule. Jpn J Clin Radiol 28:1465–1471Google Scholar
- 24.Furui S, Yamauchi T, Itai Y, Ohtomto K Epithelioid hemangioendothelioma. (in preparation)Google Scholar
- 27.Halvorsen RA, Korobkin M, Ram PC, Thompson WM (1982) CT appearance of focal fatty infiltration of the liver. AJR 139:227–281Google Scholar