Since the introduction of Magnetic Resonance Imaging (MRI) as a diagnostic technique, the number of people exposed to electromagnetic fields (EMF) has increased dramatically. In this review, based on the results of a pioneer study showing in vitro and in vivo genotoxic effects of MRI scans, we report an updated survey about the effects of non-ionizing EMF employed in MRI, relevant for patients’ and workers’ safety. While the whole data does not confirm a risk hypothesis, it suggests a need for further studies and prudent use in order to avoid unnecessary examinations, according to the precautionary principle.

Dissolution‐dynamic nuclear polarization (dissolution‐DNP) for magnetic resonance (MR) spectroscopic imaging has recently emerged as a novel technique for noninvasive studies of the metabolic fate of biomolecules in vivo. Since acetate is the most abundant extra‐ and intracellular short‐chain fatty acid, we focused on [1‐¹³C]acetate as a promising candidate for a chemical probe to study the myocardial metabolism of a beating heart. The dissolution‐DNP procedure of Na[1‐¹³C]acetate for in vivo cardiac applications with a 3 T MR scanner was optimized in pigs during bolus injection of doses of up to 3 mmol. The Na[1‐¹³C]acetate formulation was characterized by a liquid‐state polarization of 14.2% and a T_1Eff in vivo of 17.6 ± 1.7 s. In vivo Na[1‐¹³C]acetate kinetics displayed a bimodal shape: [1‐¹³C]acetyl carnitine (AcC) was detected in a slice covering the cardiac volume, and the signal of ¹³C‐acetate and ¹³C‐AcC was modeled using the total area under the curve (AUC) for kinetic analysis. A good correlation was found between the ratio AUC(AcC)/AUC(acetate) and the apparent kinetic constant of metabolic conversion, from [1‐¹³C]acetate to [1‐¹³C]AcC (k_AcC), divided by the AcC longitudinal relaxation rate (r₁). Our study proved the feasibility and the limitations of administration of large doses of hyperpolarized [1‐¹³C]acetate to study the myocardial conversion of [1‐¹³C]acetate in [1‐¹³C]acetyl‐carnitine generated by acetyltransferase in healthy pigs. Copyright © 2014 John Wiley & Sons, Ltd.

In recent years, the usage of radio frequency magnetic fields for biomedical applications has increased exponentially. Several diagnostic and therapeutic methodologies exploit this physical entity such as, for instance, magnetic resonance imaging, hyperthermia with magnetic nanoparticles and transcranial magnetic stimulation. Within this framework, the magnetic field focusing and shaping, at different depths inside the tissue, emerges as one of the most important challenges from a technological point of view, since it is highly desirable for improving the effectiveness of clinical methodologies. In this review paper, we will first report some of the biomedical practices employing radio frequency magnetic fields, that appear most promising in clinical settings, explaining the underneath physical principles and operative procedures. Specifically, we direct the interest toward hyperthermia with magnetic nanoparticles and transcranial magnetic stimulation, together with a brief mention of magnetic resonance imaging. Additionally, we deeply review the technological solutions that have appeared so far in the literature to shape and control the radio frequency magnetic field distribution within biological tissues, highlighting human applications. In particular, volume and surface coils, together with the recent raise of metamaterials and metasurfaces will be reported. The present review manuscript can be useful to fill the actual gap in the literature and to serve as a guide for the physicians and engineers working in these fields.

Hyperpolarization of ¹³C‐labeled energy substrates enables the noninvasive detection and mapping of metabolic activity, in vivo, with magnetic resonance spectroscopy (MRS). Therefore, hyperpolarization and ¹³C MRS can potentially become a powerful tool to study the physiology of organs such as the heart, through the quantification of kinetic patterns under both normal and pathological conditions. In this study we assessed myocardial uptake and metabolism of hyperpolarized [1‐¹³ C]pyruvate in anesthetized pigs. Pyruvate metabolism was studied at baseline and during dobutamine‐induced stimulation. We applied a numerical approach for spectral analysis and kinetic fitting (LSFIT/KIMOfit), making a comparison with a well‐known jMRUI/AMARES analysis and γ‐variate function, and we estimated the apparent conversion rate of hyperpolarized [1‐¹³ C]pyruvate into its downstream metabolites [1‐¹³C]lactate, [1‐¹³C]alanine and [¹³C]bicarbonate in a 3 T MR scanner. We detected an increase in the apparent kinetic constants (k_PX) for bicarbonate and lactate of two‐fold during dobutamine infusion. These data correlate with the double product (rate‐pressure product), an indirect parameter of cardiac oxygen consumption: we observed an increase in value by 46 ± 11% during inotropic stress. The proposed approach might be applied to future studies in models of cardiac disease and/or for the assessment of the pharmacokinetic properties of suitable ¹³C‐enriched tracers for MRS. Copyright © 2012 John Wiley & Sons, Ltd.