Pancreatic Scanning

Abstract

It has been well established that the radiographic signs of pancreatic carcinoma are found in approximately only 25 per cent of the cases later proved by surgical exploration (1). Since 1962 we have been establishing the efficacy of pancreatic scanning with selenomethionine-Se75 in the hope that by this modality the clinician may suspect pancreatic carcinoma at an earlier stage of the disease (2–7). The technic now utilized for pancreatic scanning is presented here, and the correlated results in 251 patients are tabulated. Equipment A Picker Magnascanner Model 6184P with a 5 × 2-inch sodium iodide crystal and the 85-hole broad focus 5-in. resolution depth lead collimator is utilized. Our present Magnascanner has a color digital print-out system as well as the standard photoscanning system. We have chosen the 5-inch crystal because of the increase in statistics as compared with the 3 × 2-in. crystal. A 5-in. collimator is used because of the increased resolution depth necessary in pancreatic scanning. Preparation of the Patient In recent work we found that, while our previously described protein meal did not stimulate the uptake of more selenomethionine-Se75 in the pancreas, it seemed to have an influence on the clearing of the radioisotope from the blood. Patient investigation showed that the protein meal effect can be simulated and improved upon by the intravenous administration of the standard 35 g of glucose utilized for the intravenous glucose tolerance test. Therefore, at the present time, our patients receive, after a four- to six-hour fast during which fluids are not restricted, 35 g of glucose intravenously and, one-half hour later, by the same route, selenome-thionine-Se75 (3.5 μCi per kilogram of body weight but never less than 200 μCi per patient). Scanning Technic The patient is supine with his left side elevated 6 in. from the posterior axillary to the table. This angle approximates 10 °. The probe is moved over the abdomen until the high counting rate of the liver is located (between 4,000 and 7,000 counts per minute). The porta hepatis is found and marked on the patient. Because anatomically the pancreas lies just inferior to the porta hepatis, this area is then carefully searched. In this particular patient position, the head of the pancreas is swung away from the liver, the body may be visualized, and the tail is separated from the left hepatic lobe. The pancreas is a deep organ, and therefore an attempt is made to have the collimator at a focal depth of 1–2 cm above the level of the vertebral column during the search. The normal pancreas in this time period will accumulate between 2,500 and 3,000 counts per minute. In the majority of patients, the pancreas can be outlined in the technician's mind and also on the patient.