Evaluation of basis function and linear least squares methods for generating parametric blood flow images using ¹⁵O-water and positron emission tomography

Purpose: Parametric analysis of ¹⁵O-water positron emission tomography (PET) studies allows determination of blood flow (BF), perfusable tissue fraction (PTF), and volume of distribution (V_d) with high spatial resolution. In this paper the performance of basis function and linear least squares methods for generating parametric flow data were evaluated. Procedures: Monte Carlo simulations were performed using typical perfusion values for brain, tumor, and heart. Clinical evaluation was performed using seven cerebral and 10 myocardial ¹⁵O-water PET studies. Basis function (BFM), linear least squares (LLS), and generalized linear least squares (GLLS) methods were used to calculate BF, PTF, or V_d. Results: Monte Carlo simulations and human studies showed that, for low BF values (<1 ml min^-1ml^-1), BF, PTF, and V_d were calculated with accuracies better than 5% for all methods tested. For high BF (>2 ml min^-1ml^-1), use of BFM provided more accurate V_d compared with (G)LLS. Conclusions: In general, BFM provided the most accurate estimates of BF, PTF, and V_d.