IDL software package for absolute quantification of myocardial blood flow based on [N-13] ammonia PET data

Presents a semi-automated software package to quantify myocardial blood flow (MBF) based on data obtained from a dynamic PET scan using [N-13] ammonia as tracer. The software package is written in IDL 5.0 and uses an external FORTRAN routine to perform fitting of dynamic time-activity curves obtained from small regions over the myocardium. The package includes correction for patient motion, automated definition of multiple regions and display of absolute MBF in polar map format. The effects of partial volume and blood to tissue cross-contamination are accounted for by optimizing the radial position of regions to meet fundamental assumptions of the underlying three-compartmental kinetic model. All sampled regions are saved to file to allow repeated post-processing runs. Following determination of MBF for small regions of the myocardium, a polar map display is created and the user can select large anatomical regions consisting of multiple smaller sampled regions. All corresponding time-activity curves are retrieved from file and averaged. The fitting is then performed for the averaged time-activity curve. This approach allows the extraction of time-activity curves with good statistics for clinically meaningful sections of the myocardium. Interobserver reproducibility for the determination of MBF was excellent (r=0.96).