Abstract
Microsphere technique is the reference for assessment of pulmonary blood flow (PBF) but is destructive; PET, however, can determine PBF noninvasively. Comparisons of these 2 methods are scanty. Our study aimed at comparing these 2 techniques using a mathematic model taking into account the right ventricle in determining the transit time of a tracer through lung tissue. Methods: Ten normal pigs were investigated at baseline, during dobutamine infusion, and during 10 cm H2O of positive end-expiratory pressure. Under each condition, PBF was successively measured with PET (PET-PBF) and radioactive microspheres (MS-PBF). For PET-PBF, 2 mCi (74 MBq) 15O-labeled water were injected intravenously over 20 s and PET scanning was performed for 10 min. The input function was determined noninvasively from PET and invasively from mixed venous blood withdrawals. PET-PBF was computed using a mathematic model taking into account the right ventricle in determining the transit time of the tracer through lung tissue. For MS-PBF, 1 given isotope was injected under a given condition. PET-PBF and MS-PBF for 5 lung regions were compared. Results: PET-PBF significantly correlated with MS-PBF both over all experimental points (PET-PBF = 0.79 · MS-PBF + 1,538; r = 0.79; P < 0.001) and in separate lung regions. Invasive and noninvasive input functions also correlated significantly (r = 0.90; P < 0.001). Simulations stressed the crucial role of the right ventricle to the transit time of tracer through lung tissue in the determination of PET-PBF. Conclusion: PBF can accurately be assessed using PET and a mathematic model taking into account the right ventricle in determining the transit time of a tracer through lung tissue. Noninvasive determination of the input function of the right ventricle is accurate and can readily be used for clinical applications.
Footnotes
Received Nov. 20, 2001; revision accepted Apr. 19, 2002.
For correspondence or reprints contact: Claude Guérin, MD, Service de Réanimation Médicale et Assistance Respiratoire, 103 Grande Rue de la Croix-Rousse, Lyon 69004, France.
E-mail: claude.guerin{at}chu-lyon.fr