It has been shown that insoluble Gd chelates are suitable MRI contrast agents for conditional activation by intracellular lipases. The DTPA-based, insoluble, inactive contrast agent was internalized into dendritic cells by phagocytosis. Cleavage of long aliphatic side chains by intracellular lipase activity leads to the contrast agents solubility and hereby its activation depending on the enzym...

Integration of optical and magnetic resonance imaging (MRI) methods in one setting is appealing due to the complementary nature of MRI’s high spatial and temporal resolution and the high molecular sensitivity of optical imaging. In particular, deep tissue penetration of near-infrared (NIR) photons and minimal autofluorescence in this wavelength range favors the assessment of molecular events in...

Introduction: Early detection and diagnosis of malignant tumors enable more efficacious cancer treatment at an earlier stage and improvement of cancer patients' survival and quality of the life. Magnetic resonance imaging (MRI) is a powerful imaging modality for cancer detection and diagnosis. However, current clinically used contrast enhanced MRI is not effective for molecular imaging because ...

In recent report (Nature Biotechnology 2000, 16:321-325) we presented a new approach for obtaining high resolution in vivo images of gene expression using magnetic resonance imaging (MRI). We prepared MRI contrast agents in which the access of water to the fust coordination sphere of a chelated paramagnetic ion is blocked with a galactopyranose residue that can he cleaved by beta-galactosidase,...

D. S. Gao, M. Tan, J. S. Cheung, A. M. Chow, S. J. Fan, K. W. Chan, K. Man, Z-R. Lu, and E. X. Wu Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China, People's Republic of, Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China, People's Republic of, Department of Biomedical...

Introduction Since their discovery polyhedral oligosilsesquioxanes (POSS) have found an ever increasing number of applications in material science, catalysis, as building blocks for dendrimers and only recently biomedical use (e.g. as drug carrier systems) were reported as well. In the last two years studies of silsesquioxane based contrast agents (CA) for MRI were published [1,2] in which the ...

Gas-filled microbubbles have the potential to become a unique MR contrast agent due to their magnetic susceptibility effect, biocompatibility and localized manipulation via ultrasound cavitation. In this study, two types of microbubbles, custom-made albumin-coated microbubbles (A-MB) and a commercially available lipid-based clinical ultrasound contrast agent (SonoVue), were investigated with in...

Iron oxide contrast agents have been combined with magnetic resonance imaging for cell tracking. In this review, we discuss coating properties and provide an overview of ex vivo and in vivo labeling of different cell types, including stem cells, red blood cells, and monocytes/macrophages. Furthermore, we provide examples of applications of cell tracking with iron contrast agents in stroke, mult...

Clinical diagnosis of cancers using magnetic resonance imaging (MRI) is highly dependent on contrast agents, especially for brain tumors which contain blood-brain barrier (BBB) at the early stage. However, currently mostly used low molecular weight contrast agents such as Gd-DTPA suffer from rapid renal clearance, non-specificity, and low contrast efficiency. The aim of this paper is to investi...

Gas-filled microbubbles have the potential to become a unique intravascular MR contrast agent due to their magnetic susceptibility effect, biocompatibility and localized manipulation via ultrasound cavitation. However, in vivo demonstration of microbubble susceptibility effect is limited so far and microbubble susceptibility effect is relatively weak when compared with other intravascular MR su...