SPIRAL HYDRO-CT OF THE PANCREAS IN THE TH IN-SLICE METHOD

Purpose: To evaluate a new technique for imaging the pancreas (spiral hydro-CT) based on a combination of pharmacological intestinal paralys is and water distension of the stomach and duodenum with specific refe rence to tumor detection rate, differentiation of malignant versus ben ign tumors, differential diagnosis and assessment of tumor resectabili ty. Material and methods: In an open prospective study, 151 patients w ith a suspected pancreatic neoplasm based on clinical, laboratory or o ther imaging data were examined between May 94 and October 95. Our new ly developed Hydro-CT methodology included intravenous injection of 40 mg N-butylscopolaminium bromide (Buscopan) for intestinal paralysis, gastric and duodenal wall distension by oral administration of an aver age of 1.51 warm tap water, 30 degrees RAO patient positioning, an ind ividualized contrast injection technique as determined beforehand by t ime-to-peak measurement in the portal vein and thin-slice spiral CT (3 mm increment, 6 mm table feed and 3 mm secondary reconstruction). A d etailed evaluation form was used to assess (1) tumor detection rate, ( 2) differentiation of malignant versus benign disease, (3) differentia l diagnosis, and (4) accuracy of assessment of resectability by identi fication of infiltration into adjacent organs and vessel structures re levant for resectability such as splenic, superior mesenteric, portal vein and celiac trunk, superior mesenteric, splenic and hepatic arteri es. As the gold standard for positive tumor detection surgery and micr oscopic diagnosis were used, and for negative tumor detection an event -free survival of 6 months. Results: Almost all examinations were well tolerated. In only 4% was on-site administration of a gastric tube re quired because of vomiting. In 2% of the patients a slight allergic re action to the contrast medium was seen. The prevalence of a pancreatic neoplasm was 38%. In tumor detection Hydro-CT reached an overall accu racy of 97.4% with a sensitivity of 100% and a specificity of 95.9%. I n the differentiation of benign versus malignant disease Hydro-CT reac hed an overall accuracy of 89.7% with a sensitivity of 92.5% and a spe cificity of 83.3%. The prevalence of a pancreatic carcinoma was 24%; 4 % other malignant tumors were found (distal common bile duct carcinoma , cystadenocarcinoma). Fifty-eight patients underwent surgical explora tion. In those assessment of resectability reached an overall accuracy of 95% with a sensitivity of 90.5% and specificity of 100%. Conclusio n: The new technique of Hydro-CT based on thin slice and spiral method ology, including pharmacological intestinal paralysis and water disten sion, results in a high tumor detection rate and increases sensitivity and specificity of tumor differential diagnosis and of assessment of resectability.