The role of metamizol induction for the detection of perfusion reversibility on thallium-201 myocardial perfusion scintigraphy.
OBJECTIVE
Metamizol, probably with its vascular smooth muscle relaxant effect, enhances rest myocardial perfusion with the use of technetium-99m-methoxyisobutylisonitrile. We aimed to investigate whether metamizol induction is also able to increase the detectability of the ischemic/jeopardized myocardium during thallium-201 myocardial perfusion scintigraphy (MPS).


METHODS
Twenty patients who had partially reversible/irreversible perfusion defects on their routine stress-redistribution-reinjection thallium-201 MPS were enrolled and metamizol-induced thallium-201 MPS (111 MBq thallium-201 was injected 45 min after 1 g oral metamizol) was acquired (10 min, 1 and 3 h later). Routine MPS and metamizol-induced MPS images were interpreted on the model of 17 segments using a visual uptake score (VUS; 0=normal, 1=mild, 2=moderate, 3=significant decreases, 4=no uptake). Thallium-201 uptake ratios (mean counts in the region of the perfusion defect/mean counts in the region of the normal-perfused wall) were calculated for each MPS. Blood pressure was monitored at 15-min intervals. MPS were compared with coronary angiography results.


RESULTS
Visual uptake score and thallium-201 uptake ratio results indicated that in the first and third hour metamizol-induced thallium-201 uptake was significantly higher (P<0.001) than the redistribution/reinjection studies in 26 ischemic myocardial walls. Fourteen myocardial walls showed no thallium-201 uptake on either MPS and were considered as myocardial infarction. Statistically significant but asymptomatic decreases in blood pressure were observed. Coronary angiography results were in concordance with metamizol-induced MPS.


CONCLUSIONS
Metamizol increases the detectability of ischemic/viable myocardium during MPS with thallium-201 and could be used with MPS.
Department of Nuclear Medicine, Hacettepe University, Ankara, Turkey.
Tamer
T
Aksoy
Eser Lay
EL
Ergün
Hakan
H
Ergün
D000328:Adult; D000368:Aged; D001692:Biological Transport / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D017023:Coronary Angiography; D004177:Dipyrone / Q000494:pharmacology*; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D009206:Myocardium / Q000378:metabolism; D013794:Thallium Radioisotopes / Q000378:metabolism
D013794:Thallium Radioisotopes; D004177:Dipyrone