How frequently is the thymus seen on whole-body iodine-131 diagnostic and post-treatment scans?

The purpose of the study was to determine how often the thymus is visualize d on whole-body radioiodine scans. One hundred and seventy-five patients ha d 325 diagnostic scans and 200 post-treatment scans. Activity in the medias tinum possibly consistent with the thymus was seen on seven scans in six pa tients. Four of these were diagnostic scans (three were second followup sca ns, and the fourth, a third follow-up scan). Three post-treatment scans dem onstrated mediastinal uptake. Only one patient had persistent mediastinal u ptake on both a post-treatment scan and a subsequent follow-up diagnostic s can. None of these six patients were treated as a result of this finding an d none has clinical or biochemical evidence of metastatic disease.