The clinical signi®cance of reverse redistribution in Tl 201 cardiac SPET George Koliakos 1 , Argyrios Doumas 1 , Dimitrios Altas 1 & George Louridas 2 1 Hippocrates Nuclear Medicine Center, Thessaloniki, Greece; 2 First Department of Cardiology, AHEPA University Hospital, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece Received 25 May 2000; accepted in revised form 16 November 2000 Key words: myocardial infarction, reverse redistribution, SPET, myocardial ischemia, Tl 201 Abstract In an attempt to evaluate the clinical signi®cance of reverse redistribution in Tl 201 cardiac SPET, Tl 201 SPET examinations included in the data base of our department have been retrospectively reviewed. Patients: Six hundred ninety eight patients demonstrated the pattern of reverse redistribution. For 237 of these patients' cardiac catheterization data were also available. One hundred and six patients of these had a history of myocardial infarction while the rest of them were referred for angina symptoms. Results: Catheterization showed that the infarction area was perfused by a stenosed but patent vessel in 79 of the 106 patients with a history of myocardial infarction (74.5%). Collateral circulation was evident in 21 of these 106 patients (19.8%). Only six patients (5.6%) showed a totally occluded vessel with no obvious evidence of collateral circulation. Of the 131 patients, with no myocardial infarction history, 14 (10.7%) had normal coronary vessels. The rest of the patients (89.3%) demonstrated stenotic vessels perfusing the same area where reverse redistribution was observed. Sixty-three of these patients have been reexamined after 9±36 months. On 15 of these patients (23.8%) the second scintigram showed ischemia in the same segments where reverse redistribution was initially detected. Another 17 of the above patients had a former scintigraphic examination that showed ischemia on the segments that currently demonstrated reverse re- distribution. Conclusion: The results of the present retrospective study indicate that, in patients with known coronary disease, the pattern of reverse redistribution frequently indicates the ischemic area. Introduction The appearance of a defect on the redistribution image in a region with normal initial uptake of 201 Tl images or the obvious worsening in rest im- ages of a defect observed in stress images is de®ned as reverse redistribution. This pattern has been studied by several investigators since 1979 when it was initially reported [1±3]. It has been suggested that reverse redistribution in patients with known myocardial infarction is due to abnormally high washout rate in a segment containing some viable myocardium and supplied by a patent coronary artery [4]. When the pattern of reverse redistribu- tion has been compared with PET ®ndings viable myocardium was detected in the majority of cases [5, 6]. Furthermore, reverse redistribution in pa- tients with chronic stable coronary artery disease has been associated with severe coronary artery stenosis and viable myocardium in the aected region [7±10]. Following thrombolysis, this sign is associated with a higher incidence of fatal cardiac events as well as with substantial left ventricular dysfunction [11]. On the other hand, after primary angioplasty for a ®rst acute myocardial infarction, reverse redistribution is a common ®nding, asso- ciated to a favorable outcome in these patients [12] and with improvement of systolic function in The International Journal of Cardiovascular Imaging 17: 29±35, 2001. Ó 2001 Kluwer Academic Publishers. Printed in the Netherlands. 29