High density lipoprotein (HDL), is an important natural nanoparticle that may be modified for biomedical imaging purposes. Here we developed a novel technique to create unique multimodality HDL mimicking nanoparticles by inclusion of gold, iron oxide or quantum dot nanocrystals for computed tomography, magnetic resonance and fluorescence imaging, respectively. By including additional labels in the corona of the particles, they were made multi-functional. The characterization of these nanoparticles, as well as their in vitro and in vivo behavior revealed that they closely mimic native HDL.

Purpose:To investigate the potential of spectral computed tomography (CT) (popularly referred to as multicolor CT), used in combination with a gold high-density lipoprotein nanoparticle contrast agent (Au-HDL), for characterization of macrophage burden, calcifi cation, and stenosis of atherosclerotic plaques. Materials and Methods:The local animal care committee approved all animal experiments. A preclinical spectral CT system in which incident x-rays are divided into six different energy bins was used for multicolor imaging. Au-HDL, an iodine-based contrast agent, and calcium phosphate were imaged in a variety of phantoms. Apolipoprotein E knockout (apo E-KO) mice were used as the model for atherosclerosis. Gold nanoparticles targeted to atherosclerosis (Au-HDL) were intravenously injected at a dose of 500 mg per kilogram of body weight. Iodine-based contrast material was injected 24 hours later, after which the mice were imaged. Wild-type mice were used as controls. Macrophage targeting by Au-HDL was further evaluated by using transmission electron microscopy and confocal microscopy of aorta sections. Results:Multicolor CT enabled differentiation of Au-HDL, iodinebased contrast material, and calcium phosphate in the phantoms. Accumulations of Au-HDL were detected in the aortas of the apo E-KO mice, while the iodine-based contrast agent and the calcium-rich tissue could also be detected and thus facilitated visualization of the vasculature and bones (skeleton), respectively, during a single scanning examination. Microscopy revealed Au-HDL to be primarily localized in the macrophages on the aorta sections; hence, the multicolor CT images provided information about the macrophage burden. Conclusion:Spectral CT used with carefully chosen contrast agents may yield valuable information about atherosclerotic plaque composition.q RSNA, 2010Supplemental material: http://radiology.rsna.org/lookup /suppl

Gestational diabetes mellitus (GDM) is increasing in prevalence in tandem with the dramatic increase in the prevalence of overweight and obesity in women of childbearing age. Much controversy surrounds the diagnosis and management of gestational diabetes, emphasizing the importance and relevance of clarity and consensus. If newly proposed criteria are adopted universally a significantly growing number of women will be diagnosed as having GDM, implying new therapeutic challenges to avoid foetal and maternal complications related to the hyperglycemia of gestational diabetes. This review provides an overview of clinical issues related to GDM, including the challenges of screening and diagnosis, the pathophysiology behind GDM, the treatment and prevention of GDM and the long and short term consequences of gestational diabetes for both mother and offspring.

Abstract-Nanoparticles have become more and more prevalent in reports of novel contrast agents, especially for molecular imaging, the detection of cellular processes. The advantages of nanoparticles include their potency to generate contrast, the ease of integrating multiple properties, lengthy circulation times, and the possibility to include high payloads. As the chemistry of nanoparticles has improved over the past years, more sophisticated examples of nano-sized contrast agents have been reported, such as paramagnetic, macrophage targeted quantum dots or ␣ v ␤ 3 -targeted, MRI visible microemulsions that also carry a drug to suppress angiogenesis. The use of these particles is producing greater knowledge of disease processes and the effects of therapy. Along with their excellent properties, nanoparticles may produce significant toxicity, which must be minimized for (clinical) application. In this review we discuss the different factors that are considered when designing a nanoparticle probe and highlight some of the most advanced examples. Key Words: nanotechnology Ⅲ molecular imaging Ⅲ magnetic resonance imaging Ⅲ drug delivery Ⅲ gene therapy O ne of the main current focuses of research in medical diagnostics is molecular imaging, as described in an accompanying article in this issue by Choudhury et al. Molecular imaging can facilitate early diagnosis, identify the stage of disease, provide fundamental information on pathological processes, and can be applied to follow the efficacy of therapy. Molecular imaging heavily relies on the development of sophisticated probes needed to detect biological processes on the cellular and molecular level. 1-5 Nanoparticulate probes have shown noteworthy advantages over single molecule-based contrast agents. These advantages include producing excellent contrast (eg, quantum dots 6 ), integrating multiple properties such as several types of contrast generating materials, 7 lengthy circulation time, 8,9 and the possibility to include high payloads. 10 Importantly, nanoparticles allow the components of a molecular imaging contrast agent to be easily assembled in an efficient ratio. As a result, very exciting molecular imaging results are being reported, such as agents that can be detected by multiple imaging techniques, 7 agents that also deliver therapeutics, 11 agents that detect particular cell types, 12 or agents that allow new imaging systems to be developed. 3,13 Other articles in this issue will expound on the progress that has been made by applying nanoparticles for molecular imaging in cardiovascular disease; we will confine our discussion to nanoparticle design.The design of effective nanoparticle contrast agents for molecular imaging requires careful consideration of the properties required for the application in question. Once the required properties have been established, candidate nanoparticle platforms may be identified. The particle synthesis can then be optimized to generate an assembly with the appropriate contrast/therapeutics included, optimized surface c...