Simultaneous Characterization of the Tumor Vascular Permeability, Vessel Size and Density by Using First-pass Function/ Structure Mr Imaging

Introduction Angiogenesis, the formation and development of new vascular network, is essential to tumor growth. Vascular network surrounding tumor tissues, however, exhibits abnormal functional and structural properties distinct from normal blood vessel. Functional abnormalities include higher permeability and altered blood flow, etc. Tumor vascular permeability can be assessed in vivo by using dynamic contrast enhanced–MR imaging (DCE-MRI) based vascular transfer constant (K) [1]. Structural changes related to tumor vasculature include blood vessel sizes index (VSI) and vessel densities index (VDI), which can be characterized by steady state contrast enhanced–MR imaging (SSCE-MRI) [2-3]. However, DCE-MRI and SSCE-MRI needed two different MR approaches and two different contrast agents; it was difficult to obtain the imaging for K, VSI and VDI at the same time. Simultaneous imaging for both functional and structural properties can greatly contribute to reduce scanning time in clinical diagnosis. Moreover, simultaneous assessment of K, VSI and VDI was also helpful to understand the correlation between functional and structural changes. Therefore, this study is aimed to develop First-Pass Function/Structure MR Imaging (First Pass F/S MRI) technique that can simultaneously characterize both functional and structural states of the tumor vascular network.