Comparison of fluorine-18-fluorodeoxyglucose and tritiated fluoromisonidazole uptake during low-flow ischemia.
Fluorine-18-fluoromisonidazole (FMISO) is trapped in hypoxic but viable canine myocardium. Because of the potential for its use as a marker of myocardial viability, we compared FMISO activity to [18F]fluorodeoxyglucose (FDG) activity in the same myocardial samples from eight dogs subjected to 3 hr of moderate regional myocardial ischemia.


METHODS
Tritiated FMISO was injected 15-30 min after onset of regional ischemia (40%-70% reduction in systolic wall thickening) which was maintained for 3 hr. FDG was injected after 2 hr of ischemia. Myocardial blood flow (MBF) was measured by the radiolabeled microsphere technique at the time of each radiotracer injection. At 3 hr of ischemia, the heart was excised and cut into short-axis slices. One slice encompassing both ischemic and normal tissue was cut into 64 samples. FMISO and FDG activity in each sample were normalized to the mean normal zone activity and further expressed as a function of regional MBF.


RESULTS
FMISO uptake was consistently greater than FDG uptake, although this was significantly different only for MBF, between 40%-60% of normal. When analyzed relative to endocardial-epicardial location, endocardial FMISO uptake was significantly greater in all hypoperfused samples.


CONCLUSIONS
These results suggest that FMISO is as sensitive as FDG for detecting myocardial ischemia and could be used for identification of viable myocardium.
Caldwell
J H
JH
Division of Cardiology, Department of Veterans Affairs Medical Center, Seattle, WA 98108, USA.
Revenaugh
J R
JR
Martin
G V
GV
Johnson
P M
PM
Rasey
J S
JS
Krohn
K A
KA
D000818:Animals; D003326:Coronary Circulation; D003847:Deoxyglucose / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D004285:Dogs; D005462:Fluorine Radioisotopes / Q000493:pharmacokinetics; D019788:Fluorodeoxyglucose F18; D006321:Heart / Q000000981:diagnostic imaging; D008920:Misonidazole / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000503:physiopathology; D011877:Radionuclide Imaging; D012680:Sensitivity and Specificity; D014316:Tritium / Q000493:pharmacokinetics
D005462:Fluorine Radioisotopes; C031843:fluoromisonidazole; D019788:Fluorodeoxyglucose F18; D014316:Tritium; D008920:Misonidazole; D003847:Deoxyglucose