Contrast Media & Molecular Imaging 

About: Contrast Media & Molecular Imaging is an academic journal published by Hindawi Publishing Corporation. The journal publishes majorly in the area(s): Medicine & Magnetic resonance imaging. It has an ISSN identifier of 1555-4309. It is also open access. Over the lifetime, 1615 publications have been published receiving 21908 citations. The journal is also known as: CMMI & Contrast Media Mol Imaging.

Classification and basic properties of contrast agents for magnetic resonance imaging

Abstract: A comprehensive classification of contrast agents currently used or under development for magnetic resonance imaging (MRI) is presented. Agents based on small chelates, macromolecular systems, iron oxides and other nanosystems, as well as responsive, chemical exchange saturation transfer (CEST) and hyperpolarization agents are covered in order to discuss the various possibilities of using MRI as a molecular imaging technique. The classification includes composition, magnetic properties, biodistribution and imaging applications. Chemical compositions of various classes of MRI contrast agents are tabulated, and their magnetic status including diamagnetic, paramagnetic and superparamagnetic are outlined. Classification according to biodistribution covers all types of MRI contrast agents including, among others, extracellular, blood pool, polymeric, particulate, responsive, oral, and organ specific (hepatobiliary, RES, lymph nodes, bone marrow and brain). Various targeting strategies of molecular, macromolecular and particulate carriers are also illustrated.

Influence of molecular parameters and increasing magnetic field strength on relaxivity of gadolinium- and manganese-based T1 contrast agents.

Abstract: Simulations were performed to understand the relative contributions of molecular parameters to longitudinal (r(1)) and transverse (r(2)) relaxivity as a function of applied field, and to obtain theoretical relaxivity maxima over a range of fields to appreciate what relaxivities can be achieved experimentally. The field-dependent relaxivities of a panel of gadolinium and manganese complexes with different molecular parameters, water exchange rates, rotational correlation times, hydration state, etc. were measured to confirm that measured relaxivities were consistent with theory. The design tenets previously stressed for optimizing r(1) at low fields (very slow rotational motion; chelate immobilized by protein binding; optimized water exchange rate) do not apply at higher fields. At 1.5 T and higher fields, an intermediate rotational correlation time is desired (0.5-4 ns), while water exchange rate is not as critical to achieving a high r(1). For targeted applications it is recommended to tether a multimer of metal chelates to a protein-targeting group via a long flexible linker to decouple the slow motion of the protein from the water(s) bound to the metal ions. Per ion relaxivities of 80, 45, and 18 mM(-1) s(-1) at 1.5, 3 and 9.4 T, respectively, are feasible for Gd(3+) and Mn(2+) complexes.

Comparative study of the physicochemical properties of six clinical low molecular weight gadolinium contrast agents

Abstract: This paper compares the physicochemical properties of six low molecular weight clinical complexes of gadolinium studied under identical experimental conditions Magnevist 1 , Dotarem 1 , Omniscan 1 , ProHance 1 , MultiHance 1 and Gadovist 1 were investigated by oxygen-17 relaxometry at different temperatures and by proton relaxometry at various magnetic fields, temperatures and media (pure water, zinc(II)-containing aqueous solutions and HSA-containing solutions) Osmolality, viscosity and stability versus transmetallation by zinc(II) ions were added for a more comprehensive description The relaxivities of the clinical formulations as measured in water are similar in the imaging magnetic field region, with a slightly better performance for MultiHance This can be explained by a shorter distance between the hydrogen nuclei of the water molecule bound to the Gd 3þ ion and this paramagnetic centre In contrast to the open-chain complexes, all macrocyclic systems (Dotarem, ProHance and Gadovist) are insensitive to transmetallation by zinc ions The stability of the open-chain complexes with respect to transmetallation depends on the chemical structure of the ligand, with a better stability for MultiHance The presence of human serum albumin has no significant effect on the proton relaxivity of Magnevist, Dotarem, Omniscan, ProHance and Gadovist but markedly increases the relaxivity of MultiHance because of a non-covalent interaction with the protein As a result, the relaxivity of MultiHance in HSA-containing media of fixed concentration decreases with increasing concentration of the contrast agent Copyright # 2006 John Wiley & Sons, Ltd

68Ga-PET: a powerful generator-based alternative to cyclotron-based PET radiopharmaceuticals

Abstract: PET (positron emission tomography) is a powerful diagnostic and imaging technique which requires short-lived positron emitting isotopes. The most commonly used are accelerator-produced (11)C and (18)F. An alternative is the use of metallic positron emitters. Among them (68)Ga deserves special attention because of its availability from long-lived (68)Ge/(68)Ga generator systems which render (68)Ga radiopharmacy independent of an onsite cyclotron. The coordination chemistry of Ga(3+) is dominated by its hard acid character. A variety of mono- and bifunctional chelators have been developed which allow the formation of stable (68)Ga(3+)complexes and convenient coupling to biomolecules. (68)Ga coupling to small biomolecules is potentially an alternative to (18)F- and (11)C-based radiopharmacy. In particular, peptides targeting G-protein coupled receptors overexpressed on human tumour cells have shown preclinically and clinically high and specific tumour uptake. Kit-formulated precursors along with the generator may be provided, similar to the (99)Mo/(99m)Tc-based radiopharmacy, still the mainstay of nuclear medicine.

Nanoparticle Contrast Agents for Computed Tomography: A Focus on Micelles

Abstract: Computed tomography (CT) is an X-ray-based whole-body imaging technique that is widely used in medicine. Clinically approved contrast agents for CT are iodinated small molecules or barium suspensions. Over the past seven years there has been a great increase in the development of nanoparticles as CT contrast agents. Nanoparticles have several advantages over small molecule CT contrast agents, such as long blood-pool residence times and the potential for cell tracking and targeted imaging applications. Furthermore, there is a need for novel CT contrast agents, owing to the growing population of renally impaired patients and patients hypersensitive to iodinated contrast. Micelles and lipoproteins, a micelle-related class of nanoparticle, have notably been adapted as CT contrast agents. In this review we discuss the principles of CT image formation and the generation of CT contrast. We discuss the progress in developing nontargeted, targeted and cell tracking nanoparticle CT contrast agents. We feature agents based on micelles and used in conjunction with spectral CT. The large contrast agent doses needed will necessitate careful toxicology studies prior to clinical translation. However, the field has seen tremendous advances in the past decade and we expect many more advances to come in the next decade.