Gastrointest Radiol 5, 155-160 (1980) Gastrointestinal Radiology Intestinal Pseudotumors: A Problem in Abdominal Computed Tomography Solved by Directed Techniques William M. Marks, Henry I. Goldberg, Albert A. Moss, F. Ruben Koehler, 1 and Michael P. Federle Department of Radiology, University of California, San Francisco, California, USA 1 Department of Radiology, University of Utah School of Medicine, Salt Lake City, Utah, USA Abstract. Differentiation of normal bowel loops from pathologic process by computed tomography is often difficult. Techniques are described for opacification of bowel loops via oral, rectal, and colostomy admin- istration of contrast material. Examples of abdominal and pelvic pseudotumors which were proven not to be pathologic lesions are presented. By following sim- ple techniques of bowel marking, one can avoid false positive diagnoses. Key words: Abdomen, computed tomography - Intes- tine, pseudotumor. Computed tomography has been shown to be useful for diagnosing many intra-abdominal lesions, includ- ing abscesses [1], lymphadenopathy [2], pancreatic pseudocysts [3], and pancreatic carcinoma. The differ- entiation between normal bowel loops and a patho- logic process is important in each of these entities. In many situations, a false positive diagnosis can lead to further diagnostic tests and possibly even surgery. We believe that intestinal pseudotumors are more common than is reflected in the literature. Although the use of oral and rectal contrast agents has been frequently alluded to previously [4], specific methods and examples of their utilization have not been em- phasized. The purpose of this report is to describe several techniques which can be used to reduce the likelihood and misinterpretation of bowel loops as pathologic processes and to illustrate selected cases. Address reprint requests to: Albert Moss, M.D., Department of Radiology, University of California, San Francisco, CA 94143, USA Techniques Used to Differentiate True Lesions from Pseudolesions Due to Bowel Loops When an abdominal CT scan is performed, one of the goals is to fill as much bowel as possible with iodinated contrast material or air. Most commonly, a dilute water-soluble iodinated contrast agent (Gas- trografin, diatrizoate meglumine and diatrizoate so- dium solution, E.R. Squibb & Sons, Princeton, NJ) is utilized. We usually administer the oral contrast in two segments: 16 oz (20 cc Gastrografin and 460 cc water) 30 to 45 rain prior to scanning, and an addi- tional 8 oz (10 cc Gastrografin and 230 cc water) 5 to 10 min prior to scanning. The ingestion of oral contrast at two times allows for identification of more distal bowel loops as well as the stomach and duode- num. When scanning times longer than 6 seconds are to be used, an intestinal paralytic agent is rou- tinely given. Usually 0.25 mg of glucagon is admin- istered slowly, over 15 seconds intravenously [5], or if glucagon is unavailable, 5 to 10 mg Pro-Banthine is given parenterally to patients without contraindica- tions (glaucoma, cardiac arrhythmias, intestinal ob- struction, obstructive uropathy, ulcerative colitis, or myasthenia gravis). Because of the paucity of retroperitoneal fat, oral contrast is of added importance in studying infants and children. In such cases contrast material is substi- tuted for the normal feeding prior to the study, or it is administered via nasogastric tube. When one is examining the pelvis or left lower quadrant, the rectum and left colon may be opacified by a small volume enema containing iodinated con- trast media (Fig. 1). Approximately one-half of a 10 cc Gastrografin-470 cc water mixture is admin- istered, with the remainder of the mixture necessary for hydrostatic pressure. Patients have been able to 0364-2356/80/0005-0155 $01.20 9 1980 Springer-Verlag New York Inc.