Abstract
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Objectives We investigate the metabolism rate of drug in certain organs by dynamic PET imaging to quantitatively evaluate the effectiveness and applicability of the drug without blood sampling.
Methods For the new drug development and tracking of cancer treatment, generally, the volunteers/patients need to do several blood samplings/extractions, however, not all the volunteers/patients are willing or available to do that, so here we focus on the quantitative analysis of drug metabolism by dynamic PET without blood samplings. First 20 simulation studies are conducted, in every study, a 40-min dynamic PET scan is performed just after the injection of the proposed drug. In our solution framework, compartment models are adopted for each organ; all the parameters of each compartment model are calculated separately without blood samplings (focus on the parameters in targeted ROIs, heart, kidney) and compared with the true values from simulation settings. Then patient studies are conducted under same circumstance to further validate our method. When the parameters meet the predefined standards and are proved to be useful, the parameters are normalized and further used as guidance for treatment planning.
Results In our dynamic PET studies, by conventional method, the biases of delivery rate of drug from blood to tissues are 0.11 with blood samplings and 1.24 without blood samplings, while by our method, the biases are 0.057 and 0.24 respectively. Similarly, for the binding rate of drug and cells inside tissues, the bias of conventional method without blood sampling is 0.513, while bias of our method is only 0.12. Other parameters show similar results. Then the parameters are normalized to be in (0,1) and show the utilization rate of the drug then guide the next treatment.
Conclusions Our method is proved to be useful to quantitatively calculate the metabolism rate of drugs without blood sampling