Reliability of technetium-99m Q12 and thallium-201 myocardial activity measurements after triphenyl tetrazolium chloride myocardial staining by perfusion.
OBJECTIVE
Investigations in animal models of severe myocardial ischemia or infarction use triphenyl tetrazolium chloride (TTC) staining to document infarction size histologically and to correlate these data with uptake measurements of radiolabeled tracers. Previously published data suggest that TTC staining itself has an important impact on myocardial tracer activity measurements. The authors hypothesized that TTC staining by perfusion has no significant effect on relative regional myocardial activity measurements of technetium-99m Q12 and thallium-201 in an open-chest canine model.


METHODS
Eight dogs underwent left anterior descending artery occlusion for 2 hours with 30 minutes of reperfusion, followed immediately by injection of technetium-99m Q12 (n = 4) or thallium-201. Total myocardial activity was recorded in a dose calibrator, and regional myocardial samples were obtained by Cope needle biopsies from the ischemic and normal zones, both before and after TTC staining.


RESULTS
The mean percent activity retention for the whole heart after perfusion staining with TTC was significantly reduced when compared to the preperfusion value for both technetium-99m Q12 and thallium-201. Regional measurements revealed no significant difference between the mean percent retention of technetium-99m Q12 in the ischemic and normal zones. After TTC perfusion, regional mean percent retention of thallium-201 was similar in the ischemic and normal zones.


CONCLUSIONS
In a canine model of myocardial ischemia and infarction with reperfusion, TTC staining can be performed by coronary artery perfusion without significantly affecting comparative regional measurements of either technetium-99m Q12 or thallium-201. Whole heart tracer retention is significantly reduced by TTC perfusion staining, but thallium-201 is more affected than technetium-99m Q12.
Lenihan
D J
DJ
Department of Internal Medicine, University of Cincinnati, Ohio 45267-0542, USA.
McGoron
A J
AJ
Gabel
M
M
Walsh
R A
RA
Gerson
M C
MC
D000818:Animals; D004396:Coloring Agents; D004285:Dogs; D005663:Furans; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000000981:diagnostic imaging* / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D015609:Organotechnetium Compounds; D010477:Perfusion; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D013778:Tetrazolium Salts; D013794:Thallium Radioisotopes
D004396:Coloring Agents; D005663:Furans; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D013778:Tetrazolium Salts; D013794:Thallium Radioisotopes; C078496:technetium Tc 99m Q12; C009591:triphenyltetrazolium