Compartmental analysis of technetium-99m-teboroxime kinetics employing fast dynamic SPECT at rest and stress.
We have examined the feasibility of compartmental analysis of 99mTc-teboroxime kinetics in measuring physiological changes in response to adenosine-induced coronary vasodilation. To evaluate the effect of tracer recirculation on 99mTc-teboroxime kinetics in the myocardium, we also compared compartmental analysis with washout analysis (monoexponential fitting), which does not account for this effect.


METHODS
Eight healthy male volunteers were imaged using fast dynamic SPECT protocols (5 sec per tomographic image) at rest and during adenosine infusion. A two-compartment model was used and compartmental parameters K1 and k2 (characterizing the diffusion of 99mTc-teboroxime from the blood to the myocardium and from the myocardium to the blood, respectively) were fitted from myocardial time-activity curves and left ventricular input functions.


RESULTS
Both K1 and washout estimates for the whole left ventricular myocardium changed significantly in response to coronary vasodilation. Mean stress-to-rest (S/R) ratios were almost two times higher for K1 (S/R = 2.7 +/- 1.1) than for washout estimates (S/R = 1.5 +/- 0.3). Estimation of K1 for all local regions, except the septal wall, is feasible because variations in K1 estimates for all local regions, except the septum during stress, are comparable with those for the global region.


CONCLUSIONS
We conclude that quantitative compartmental analysis of 99mTc-teboroxime kinetics provides a sensitive indicator for changes in response to adenosine-induced coronary vasodilation.
Chiao
P C
PC
Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor.
Ficaro
E P
EP
Dayanikli
F
F
Rogers
W L
WL
Schwaiger
M
M
D000241:Adenosine; D003331:Coronary Vessels / Q000187:drug effects; D005240:Feasibility Studies; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics; D010091:Oximes / Q000493:pharmacokinetics; D012680:Sensitivity and Specificity; D013997:Time Factors; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014664:Vasodilation / Q000187:drug effects
D015609:Organotechnetium Compounds; D010091:Oximes; D000241:Adenosine; C060156:technetium Tc 99m teboroxime