Absolute quantitation of myocardial blood flow with Tl-201 and dynamic SPECT in canine: optimisation and validation of kinetic modelling

: Iida H, Eberl S, Kim KM, Tamura Y, Ono Y, Nakazawa M, Sohlberg A, Zeniya T, Hayashi T, Watabe H

Publisher: SPRINGER

: 2008

: European Journal of Nuclear Medicine and Molecular Imaging

: EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING

: EUR J NUCL MED MOL I

: 35

: 5

: 896

: 905

: 10

: 1619-7070

DOI: https://doi.org/10.1007/s00259-007-0654-4

Tl-201 has been extensively used for myocardial perfusion and viability assessment. Unlike Tc-99m-labelled agents, such as Tc-99m-sestamibi and Tc-99m-tetrofosmine, the regional concentration of Tl-201 varies with time. This study is intended to validate a kinetic modelling approach for in vivo quantitative estimation of regional myocardial blood flow (MBF) and volume of distribution of Tl-201 using dynamic SPECT.Method Dynamic SPECT was carried out on 20 normal canines after the intravenous administration of Tl-201 using a commercial SPECT system. Seven animals were studied at rest, nine during adenosine infusion, and four after beta-blocker administration. Quantitative images were reconstructed with a previously validated technique, employing OS-EM with attenuation-correction, and transmission-dependent convolution subtraction scatter correction. Measured regional time-activity curves in myocardial segments were fitted to two- and three-compartment models. Regional MBF was defined as the influx rate constant (K (1)) with corrections for the partial volume effect, haematocrit and limited first-pass extraction fraction, and was compared with that determined from radio-labelled microspheres experiments.Results Regional time-activity curves responded well to pharmacological stress. Quantitative MBF values were higher with adenosine and decreased after beta-blocker compared to a resting condition. MBFs obtained with SPECT (MBFSPECT) correlated well with the MBF values obtained by the radio-labelled microspheres (MBFMS) (MBFSPECT=-0.067+1.042 MBFMS, p < 0.001). The three-compartment model provided better fit than the two-compartment model, but the difference in MBF values between the two methods was small and could be accounted for with a simple linear regression.Conclusion Absolute quantitation of regional MBF, for a wide physiological flow range, appears to be feasible using Tl-201 and dynamic SPECT.