Effects of metabolite correction for arterial input function on quantitative receptor images with 11C-flumazenil in clinical positron emission tomography studies

To evaluate the effect of inputs estimated from different methods for metabolite correction on binding potential (BP) of C-flumazenil (FMZ). Five healthy volunteers underwent C-FMZ positron emission tomography. Arterial blood was sampled to obtain plasma radioactivity and metabolite fraction, followed by estimation of input functions with several methods. Binding potential images for different input functions and that using the noninvasive graphic method were calculated. Images of standardized uptake value (SUV) with different acquisition times were also compared. Binding potential images calculated from arterial inputs were almost equivalent, and regional values were not significantly different irrespective of methods for metabolite correction as well as the noninvasive graphic plot method. Standardized uptake value images showed less contrast compared with quantitative BP images, and the regional values varied depending on scan time. Statistical parametric mapping analysis showed significant regional differences between BP and SUV images. Binding potential images were equivalent irrespective of calculation methods; however, SUV was not appropriate for quantitative evaluation.