Myocardial perfusion with [11C]methyl triphenyl phosphonium: measurements of the extraction fraction and myocardial uptake.
The present study describes extraction fraction and uptake measurements of the [11C]methyl triphenyl phosphonium (11C-MTP), a promising positron emission tomography (PET) agent for cardiac imaging. PET imaging was performed in mongrel dogs. Under physiological flow conditions 11C-MTP uptake reached a maximum within the first 10 minutes after injection and remained constant during the entire observation period of 80 minutes. Over the same time period, the heart/blood ratio was 46-106:1, and the heart/lung ratio 14:1. Following permanent occlusion of the left anterior descending coronary artery, 11C-MTP uptake in the normally perfused myocardium also reached a maximum at 10 minutes after injection, whereas in the infarcted area there was no significant accumulation of 11C-MTP. For a time period of 80 minutes the noninfarcted/infarcted myocardium ratio was 12:1. Extraction was measured in anesthetized dogs with a double isotope method using 99mTc-HSA as the reference tracer. The extraction fraction was 91% at a flow of 69 mL/min/100g. As flow increased to five-fold (342 mL/min/100g) following administration of adenosine, extraction fell to 61%. Following coronary artery occlusion, the 11C-MTP content in the myocardium was highly correlated (r = 0.93, p < 0.01; y = 10.46 + 0.92x) with the microsphere determined regional myocardial blood flow.
Krause
B J
BJ
Division of Nuclear Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland.
Szabo
Z
Z
Becker
L C
LC
Dannals
R F
RF
Scheffel
U
U
Seki
C
C
Ravert
H T
HT
Dipaola
A F
AF
Wagner
H N
HN
D000818:Animals; D002250:Carbon Radioisotopes; D003326:Coronary Circulation / Q000502:physiology; D003331:Coronary Vessels / Q000503:physiopathology*; D004285:Dogs; D006321:Heart / Q000000981:diagnostic imaging*; D009861:Onium Compounds; D014055:Tomography, Emission-Computed / Q000379:methods*; D014320:Triphenylmethyl Compounds
D002250:Carbon Radioisotopes; D009861:Onium Compounds; D014320:Triphenylmethyl Compounds; C011561:triphenylmethylphosphonium