Magnetic
resonance angiography (MRA) is an important imaging technique
that can be used to identify and characterize various types of vascular
diseases. However, currently used molecular contrast agents are unsuitable
for MRA due to the short intravascular retention time, the whole-body
distribution, and the relatively low contrast effect. In this study,
we developed a vascular analysis contrast agent (i.e., VasCA) for MRA, which is a simple and biocompatible 1:1 host–guest
assembly of PEGylated β-cyclodextrin and gadolinium chelate
with renal clearable size and high relaxivity (r
1 = 9.27 mM–1 s–1). Its
biocompatibility was confirmed by in vivo animal
studies as well as in vitro 3D cell culture. In a
tumor-bearing rat model, VasCA circulated in the blood vessels much
longer (4.3-fold increase) than gadoterate meglumine (Dotarem) and
was mainly excreted by the renal system after intravenous injection.
This feature of VasCA allows characterization of tumor microvasculature
(e.g., feeding and draining vessels) as well as visualization
of small vessels in the brain and body organs. Furthermore, after
treatment with an angiogenesis inhibitor (i.e., sorafenib),
VasCA revealed the vessel normalization process and allowed the assessment
of viable and necrotic tumor regions. Our study provides a useful
tool for diverse MRA applications, including tumor characterization,
early-stage evaluation of drug efficacy, and treatment planning, as
well as diagnosis of cardiovascular diseases.