A comparison of the redistribution and reinjection techniques in dipyridamole thallium tomography

The effect of the injection of additional thallium after a redistribution study and prior to a further resting study was evaluated in 21 patients with angiographically proven coronary artery disease. Using dipyridamole as the stress mechanism, the studies were carried out tomographically and the results analysed quantitatively with the Bullseye technique. Two patients had normal scans. Of the remaining 19, 11 patients had a perfusion defect which appeared irreversible on redistribution imaging. However, six of these patients demonstrated improved or normal uptake after the second injection of thallium. Of the eight patients with a reversible defect, two revealed considerably greater reversibility after reinjection. These results indicate that the reinjection of thallium prior to the resting study significantly (P < 0.02) improves the detection rate of ischaemia during dipyridamole thallium tomography.