Reinjection of thallium after stress-redistribution imaging

To the Editor: Dilsizian et al. (July 19 issue)¹ report the results of reinjection of thallium-201 after stress—redistribution imaging in an attempt to enhance the detection of viable myocardium. On the basis of the observation that 49 percent of defects found to be irreversible and fixed on stress—redistribution imaging with thallium improved after reinjection, they conclude that reinjection improves the sensitivity for detecting viable myocardium. Similar results have been reported recently by others, with both standard 24-hour delayed imaging² and reinjection.³ It is unclear, however, why the authors chose an initial dose of 2 mCi of thallium-201 rather than.