Influence of magnetic resonance contrast media on the activity of histamine inactivating enzymes

Physicochemical characterization of a novel graphene-based magnetic resonance imaging contrast agent

We report the synthesis and characterization of a novel carbon nanostructure-based magnetic resonance imaging contrast agent (MRI CA); graphene nanoplatelets intercalated with manganese (Mn²⁺) ions, functionalized with dextran (GNP-Dex); and the in vitro assessment of its essential preclinical physicochemical properties: osmolality, viscosity, partition coefficient, protein binding, thermostability, histamine release, and relaxivity. The results indicate that, at concentrations between 0.1 and 100.0 mg/mL, the GNP-Dex formulations are hydrophilic, highly soluble, and stable in deionized water, as well as iso-osmolar (upon addition of mannitol) and iso-viscous to blood. At potential steady-state equilibrium concentrations in blood (0.1–10.0 mg/mL), the thermostability, protein-binding, and histamine-release studies indicate that the GNP-Dex formulations are thermally stable (with no Mn²⁺ ion dissociation), do not allow non-specific protein adsorption, and elicit negligible allergic response. The r₁ relaxivity of GNP-Dex was 92 mM⁻¹s⁻¹ (per-Mn²⁺ ion, 22 MHz proton Larmor frequency); ~20- to 30-fold greater than that of clinical gadolinium (Gd³⁺)- and Mn²⁺-based MRI CAs. The results open avenues for preclinical in vivo safety and efficacy studies with GNP-Dex toward its development as a clinical MRI CA.

Haemorrhage Detection in Brain Metastases of Lung Cancer Patients using Magnetic Resonance Imaging

Magnetic resonance susceptibility-weighted imaging (SWI) is a new, highly-sensitive technique used to detect haemorrhage. This study evaluated the ability of magnetic resonance imaging (MRI) to detect haemorrhage in 45 lung cancer patients with brain metastases and compared the results with T2*-weighted imaging (T2*WI) and contrast-enhanced T1-weighted imaging (CE-T1WI). Eighty-nine haemorrhagic brain metastases were identified in 31 patients using SWI, 68 were identified in 23 patients using T2*WI and 46 were identified in 14 patients using CE-T1WI. Most micro-bleeds could only be identified by SWI. It was concluded that haemorrhage is a frequent occurrence in brain metastases originating from lung cancer and that haemorrhage can be detected using SWI in a majority of brain metastases patients.