Normal and abnormal patterns of Tc-99m pertechnetate distribution in Meckel’s scans

Objectives: After reviewing this presentation, attendeesshould be able to 1) describe the normal, physiologic patterns of radiotracer distribution after intravenously administered Tc-99m pertechnetate, 2) discuss the pathophysiologic basis for Tc-99m pertechnetate uptake in Meckel’s diverticulum, and 3) recognize abnormal patterns of radiotracer distribution and identify potential reasons for them. Abstract: The Meckel’s scan is well-regarded for its straightforward execution, simple radiopharmaceutical preparation, and high diagnostic accuracy. The fact that the radiotracer utilized here is simply Tc-99m pertechnetate, eluted directly from the generator and free of any additional radiochemical processing, may suggest that abnormal patterns of radiotracer distribution should not be expected and might even be impossible. However, we have observed abnormal patterns of Tc-99m pertechnetate distribution with obvious delayed clearance from the liver and cardiac blood pool. Beyond the Meckel’s scan, Tc-99m pertechnetate is extensively utilized in nuclear medicine, making it even more important to recognize the possibility of its altered biodistribution and delayed clearance. In this presentation, we will discuss 1) the etiology, epidemiology, pathophysiology, and management of Meckel’s diverticulum, 2) the use of Tc-99m pertechnetate in Meckel’s scans and its other indications in nuclear medicine, 3) examples of positive and negative Meckel’s scans, 4) the potential effect of certain medications on the distribution of Tc-99m pertechnetate, 5) how altered biodistribution might affect the accuracy of Meckel’s scan, 5) illustrative cases of abnormal distribution and clearance of Tc-99m pertechnetate from the liver and cardiac blood pool, and finally, 6) potential agent-specific and patient-specific factors that may have contributed to the observed abnormal distribution.