A. Zouaoui ct al : CT scan of gastrointestinal tract using Cal Scan
CT Scan of gastrointestineal tract using a new calcium-based contrast medium (Cal Scan) (17.03.89) A Z o u a o u i t,2, F H e i t z 2, F M e y e r 2, D H e i t z 2, J M e t z g e r 2 a n d E L e s m a n e 3 Laboratoire d'Anatomic, UFR Biom6dicale, Facultd de M6decine, 45, rue des Saints-P~res, F-75270 Paris Cedex 06, France ~ervice de Radiologie H6pital Pitif-Salp&ri6re 3 acult6 des Sciences Paris VI
CT Study of the abdominopelvic region is .CUrrently made using media containing JOdine or barium, which allow identification of the lumen of the gastrointestinal tract. Classically, 500 ml of contrast is administered by the upper route for study of the stomach and small bowel and over 500 ml by the lower route for study of the large bowel. Only fragmentary images are obtainable xvith these conventional media because they Pass through organs with marked differences ~f phi (thus the pH of the stomach is rather eid while that of ttie small bowel is heoretically basic). These modifications of pl-t produce a precipitation effect which is ~arked by fragmentation of the opaque 'i~e~ (Fig. 1) This gives non-uniform lu~ages of the " gastromtestmal ' tract w*th alternation of opacified and non-opacified ZOnes. Further, the coexitence in the bowel of media with such different densities as ingested contrast media and air produces
partial volume effects giving rise to striae that make interpretation of the images very difficult (Fig. 2). We now report on a new contrast medium, calcium glucono-glucoheptonate (Cal Scan*), which minimizes the major drawbacks. Cal Scan is presented in 2 forms: a 15% solution for ingestion and a 20% solution for enemas. It is given in 2 stages, one half 45 rain before the examination and the remainder 5 rain before this is carried out. During the course of the examination a hypotonie (or isotonic) agent is also given as well as intravenous injection of an iodized medium. These agents modify behavior of the contrast in the bowel so that it is uniformly dispersed and the fragmentation disappears (Fig. 3). The alimentary lumen is completely opacified. For the same reason, the partial volume effect disappears completely. The
other advantage of Cal Scan is that the density of the opacity obtained lies between 40 and 120 Hounsfield units. This prevents it from masking a disease of the alimentary tract or neighboring organs, whose densities lie classically outside this range, The intravenous injection of the iodized medium supplements the examination and shows up the walls of the tract. Thus, with a calciumcontaining solution the CT study reveals lesions of the walls of the gastrointestinal tract which previously were visible only on conventional double-contrast radiologic studies or at fibroscopy. Moreover, this better visualization makes it possible to display the deforming effecfs on the alimentary tract of lesions of adjacent organs, such as involvement of the rectum in tumoral uterine pathology (Fig. 4).
Submitted April 4, 1989/Accepted April 12, 1989
Figs. 1-4 1 Fragmentary appearance of contrast medium, alimentary tract poorly injected 2 Coexistence of 2 densities (opaque and gaseous) producing partial volume effects 3 Good opacification of small bowel loops without fragmentation of contrast medium 4 Intravenous injection of iodized medium opacities the uterine wall and fills the bladder. The rectum is clearly visible. The relations between the uterus and rectum are normal 1 Aspect fragmentaire du produit de contraste, tube digestif mal inject6 2 Coexistence de 2 densit6s (opaque et a6rique) entra[nant des effets de volume partiel 3 Bonne opacification des anses gr6ies sans fragmentation du produit de contraste 4 L'iode inject6 par vole veineuse opacifie une paroi ut6rine et remplit la vessie. Le rectum est bien visible. Les rapports entre I'utdrus et le rectum sont normaux