Istituto di Fisiologia Clinica     
Marzullo P., Gimelli A., Cuocolo A., Pace L., Marcassa C., Sambuceti G., Galli M., Giorgetti A., Stefanini S., Parodi O., L'Abbate A. Thallium-201 reverse redistribution at reinjection imaging correlated with coronary lesion, wall motion abnormality and tissue viability. In: The Journal of Nuclear Medicine, vol. 37 (5) pp. 735 - 741. Society of Nuclear Medicine, 1996.
Previous studies based on standard stress-redistribution 201Tl scintigraphy provided conflicting results about the clinical significance of 201Tl reverse redistribution. Recent observations indicate that the majority of these defects normalize following reinjection reflecting viable myocardium. Methods: In this study, the meaning of reverse redistribution occurring at reinjection imaging, its relation to standard 4-hr redistribution, coronary lesion, abnormal wall motion and tissue viability were assessed. A region with normal activity in the stress image was considered as having reverse redistribution if 201Tl activity at reinjection imaging was definitely abnormal with a decrease in relative tracer uptake >15% of the peak. From a series of 270 patients, 29 showed reverse redistribution. Of these 29 patients, 27 had evidence of previous myocardial infarction. Coronary lesions were detected in all but 1 patient. Average ejection fraction was 0.38 0.11. Results: On a segmental basis, 50/377 regions showed the pattern of reverse redistribution. A significant coronary lesion (50%) was found in 78% of these regions; occlusion rate was 50%, and collateral circulation was found in 35% of occluded vessels. Hypokinesis or akinesis was present in 72% of segments. Tissue viability, defined as an uptake >55% of the peak, was found in 44% of these segments. The 50 segments showing reverse redistribution were divided into two groups according to an abnormal uptake also at 4-hr redistribution (group 1, 25 segments) or appearing only following reinjection (group 2, 25 segments). Despite segments of group 1 showing a higher degree of coronary stenosis (80 32 versus 59 43%, p < 0.01), a similar rate of coronary occlusion, ventricular dysfunction and maintained viability was found in the two groups. Conclusion: Reverse redistribution in chronic coronary artery disease is frequently associated with significant coronary lesion, collateral-dependent dysfunctioning myocardium and preserved tissue viability. The occurrence of reverse redistribution following reinjection expands the indication for viability imaging to all patients with known coronary artery disease and regional wall motion abnormalities who undergo diagnostic and prognostic 201Tl scintigraphy.
Subject thallium-201 scintigraphy
regional ventricular function
coronary artery disease

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