A Comparative Study of Four Tests of Pancreatic Function in the Diagnosis of Pancreatic Disease

Four tests of pancreatic function—the conventional and subtraction pancreas scans, the Lundh test, and the radioselenium test—were performed in 80 patients in an attempt to clarify the indications for performing one or more of these tests in the diagnosis of pancreatic disease. All four tests were performed simultaneously in a single two-hour session. The scans were marked blindly by three independent observers. The radioselenium and Lundh tests were equally accurate in distinguishing between the normal and the abnormal pancreas. Thus only one of these two tests need be performed in a patient referred for pancreatic investigation. Routine performance of both a conventional and a subtraction scan is, however, indicated because the subtraction scan gave fewer false positive results in normal patients whereas the conventional scan yielded better resolution of filling defects. A normal pancreatic scan indicated a 94 per cent probability that the pancreas was normal. If the scan was normal the intubation test was always normal. An abnormal intubation test indicated a 100 per cent probability that the pancreas was abnormal. If the intubation test was abnormal the scan was always abnormal. However, abnormal (false positive) scans were seen in 25 per cent of the normal subjects and normal (false negative) intubation tests were seen in 35 per cent of patients with pancreatic carcinoma. Abnormal scans were seen in 95 per cent of patients with pancreatic carcinoma and in some instances the scans were very suggestive of carcinoma as a localized filling defect was seen. Thus the pancreatic scan is more reliable than an intubation test in establishing a diagnosis of pancreatic carcinoma. Diagnostic ability can, in general, be best improved by performing either one of the duodenal intubation tests together with both the conventional and the subtraction scan. But for some patients, either the scans on their own (if normal) or an intubation test alone (if abnormal) will suffice.