Input functions derived from ~(18)F-FDG PET/CT imaging in canines

Objective The input functions are of necessity in quantitative PET imaging.In this study the authors tried to derive non-invasively the input functions from canine ~(18)F-FDG PET/CT scans,as compared with standardized input functions determined invasively from serial arterial plasma sampling. Methods Five dogs underwent serial PET/CT scans using dynamic scanning protocol after ~(18)F-FDG admin- istration.Meanwhile,continuous arteries blood samples were collected through catheters inserted into femo- ral arteries of the dogs.Image derived input functions(IDIF)were obtained using ROI defined on dynamic PET/CT images over various cardiovascular structures such as left ventricle(LV),right ventricle(RV), right atria(RA),aortic arch(AC),ascending aorta(AA)and descending aorta(DA).Area under curve (AUC)method was used to calculate each input function from arterial plasma sampling.Canine myocardial inhibition constant(Ki)values were estimated using Patlak graphical analyses.Results IDIF from ~(18)F-FDG PET/CT scans were significantly correlated with input functions derived from arterial plasma sampling using AUC(r≥0.97).When AC and DA regions were chosen for the calculation,the mean Ki estimated thereby using IDIF were almost identical to those using input functions from artery blood sampling analyses(the rati- os between two sets of Ki being 1.0±0.1 and 1.1±0.1 respectively).Conclusion It might be feasible to use IDIF derived from ROIs over AC and DA on a dynamic ~(18)F-FDG PET/CT scan,as a non-invasive proce- dure,for quantitative analyses.