Contributions to imaging research on the pancreas in rats

Summary Abnormalities of the pancreas result in diseases such as pancreatitis, diabetes, and pancreatic tumors. The high incidence of pancreatic diseases has placed imaging diagnosis in a crucial position. To improve diagnosis technique and investigate new therapeutic strategies, rats have been widely used in pre-clinical pancreatic researches. However, due to the minute anatomy of ever moving organs in the abdomen, it proves extremely challenging to image rat pancreas. In this program of doctoral thesis, serial efforts have been made to provide optimal solutions to rodent pancreatic imaging by using standard clinical facilities. Open-source software and in-house built programs were used for data processing. First, to obtain a full overview of rat pancreas on images, detailed visualization of a complete pancreas and topographic landmarks was accomplished through contrast enhanced CT and MR imaging in a rat postmortem model, being demonstrated with 3D rendering. Second, non-invasive MRI methods were explored to investigate the Caerulein induced acute pancreatitis in rats, in which volumetric and T2 relaxation measurements were elaborated to depict edematous pancreas. Afterwards, the reliability of 3D isotropic MRI and quantitative multi-parametric MRI (relaxation mapping, diffusion and perfusion protocols) to characterize an orthotopic pancreatic head tumor model in rats was investigated. Moreover, therapeutic efficacies of a vascular disruption agent towards pancreatic and hepatic tumors in rats were compared by using the above-optimized imaging techniques in combination with dynamic T1 mapping to facilitate assessment of heterogeneous therapeutic responses and pixel-wise pharmacokinetic modeling. Finally, proposed solutions for practical problems confronted in rat imaging using standard clinical MRI settings were summarized. This thesis work may help develop routine protocols for further theragnostic investigations on rodent pancreatic diseases in the context of translational medicine.nrpages: 114status: publishe