MRI 뉴로영상 연구실

Imaging tumor microenvironment (viable, necrotic and hypoxic region) can provide prognostic information about the risk of developing tumor metastases and regional sensitivity and maybe used potentially for localized dose escalation in radiation therapy. Dynamic contrast enhanced MRI and diffusion MRI provide important perfusion and structural information of tumor and thus may be surrogate of of tumor microenvironment. PET provides unique molecular imaging capability to image target molecules, which bind to specific microenvironments with high sensitivity. Our group aims to correlate perfusion/hypoxia parameters derived from in-vivo MR and PET measurements with tumor sections to establish translational MR methodology to image relevant tumor microenvironments in-vivo. Acquisitions of dual T1 and T2* contrasts from a single exogenous magnetic resonance (MR) agent is attracttive. So far, main efforts were focused on the synthesis of new nanoparticles. Dextran-coated SPION were synthesized and characterized to have a core diameter distribution of 5-10 nm (TEM) and a hydrodynamic diameter of 20 nm (DLS). FLASH image showed negative contrast, while UTE image showed positive vessel/tissue contrast, consistent with steady-state signal enhancement calculations. Furthermore, co-registration of the dual-contrast images over the same anatomical region provided complementary information, since negative FLASH contrast provides better sensitivity for small and thin vessels, and positive UTE contrast reduces false contrast from erroneously darkening signal intensities of FLASH images with SPION. Our simulations and the results of in vitro and in vivo experiments validates the finding that SPION-assisted dual-mode acquisitions of positive and negative contrast improves the accuracy, sens