[Usefulness of exercise Tl-201 myocardial scintigraphy: comparison with positron emission tomography].
To evaluate the usefulness of exercise Tl-201 myocardial scintigraphy, we performed positron emission tomography and conventional exercise Tl-201 emission computed tomography (ECT) in 33 patients with old anterior myocardial infarction (Q-MI: 24, non Q-MI: 9). N-13 ammonia was used as a blood flow tracer, and imaging was performed at rest and after multistage, symptom-limited ergometer exercise. After the administration of F-18 deoxyglucose (FDG) at rest in the fasting state, metabolic imagings were performed to evaluate regional exogenous glucose utilization. Tl-ECT showed fixed defects in 19 of the 33 patients, redistribution of the tracer in nine and no defects in five. All patients having partial or complete redistribution on Tl-ECT showed exercise-induced ischemia on PET with N-13 ammonia and an increased uptake of FDG in the hypoperfused region, suggesting the presence of ischemic but potentially salvageable tissues. In addition, PET with N-13 ammonia detected periinfarct ischemia in nine of the 19 with fixed defects on Tl-ECT, and increased uptakes of FDG were observed in eight of the 19. These results indicate that Tl-ECT may underestimate myocardial viability in clinically infarcted regions. Further studies are needed to determine whether restoring coronary flow improves wall motion in regions with fixed defects on Tl-ECT.
Fudo
T
T
Third Division of Internal Medicine, Kyoto University.
Kambara
H
H
Hashimoto
T
T
Hayashi
M
M
Tamaki
N
N
Yonekura
Y
Y
Yamashita
K
K
Konishi
J
J
Tamaki
S
S
Kawai
C
C
D000328:Adult; D000368:Aged; D000641:Ammonia; D003847:Deoxyglucose; D005080:Exercise Test; D005260:Female; D005462:Fluorine Radioisotopes; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000503:physiopathology; D009590:Nitrogen Radioisotopes; D013794:Thallium Radioisotopes; D014022:Tissue Survival; D014055:Tomography, Emission-Computed; D015899:Tomography, Emission-Computed, Single-Photon
D005462:Fluorine Radioisotopes; D009590:Nitrogen Radioisotopes; D013794:Thallium Radioisotopes; D000641:Ammonia; D003847:Deoxyglucose