Objectives Standardization is an important milestone in the validation of DWI-based parameters as imaging biomarkers for renal disease. Here, we propose technical recommendations on three variants of renal DWI, monoexponential DWI, IVIM and DTI, as well as associated MRI biomarkers (ADC, D, D*, f, FA and MD) to aid ongoing international efforts on methodological harmonization. Materials and methods Reported DWI biomarkers from 194 prior renal DWI studies were extracted and Pearson correlations between diffusion biomarkers and protocol parameters were computed. Based on the literature review, surveys were designed for the consensus building. Survey data were collected via Delphi consensus process on renal DWI preparation, acquisition, analysis, and reporting. Consensus was defined as ≥ 75% agreement. Results Correlations were observed between reported diffusion biomarkers and protocol parameters. Out of 87 survey questions, 57 achieved consensus resolution, while many of the remaining questions were resolved by preference (65-74% agreement). Summary of the literature and survey data as well as recommendations for the preparation, acquisition, processing and reporting of renal DWI were provided. Discussion The consensus-based technical recommendations for renal DWI aim to facilitate inter-site harmonization and increase clinical impact of the technique on a larger scale by setting a framework for acquisition protocols for future renal DWI studies. We anticipate an iterative process with continuous updating of the recommendations according to progress in the field.

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Cardiac magnetic resonance imaging (MRI) on small animals is possible but remains challenging and not well standardized. This publication aims to provide an overview of the current techniques, applications and challenges of cardiac MRI in small animals for researchers interested in moving into this field. Solutions have been developed to obtain a reliable cardiac trigger in both the rat and the mouse. Techniques to measure ventricular function and mass have been well validated and are used by several research groups. More advanced techniques like perfusion imaging, delayed enhancement or tag imaging are emerging. Regarding cardiac applications, not only coronary ischemic disease but several other pathologies or conditions including cardiopathies in transgenic animals have already benefited from these new developments. Therefore, cardiac MRI has a bright future for research in small animals.

This combined technology may constitute a new advance in DCD organ diagnostics prior to transplantation, as it allows direct assessment of ATP concentration, which provides a reliable indicator for organ bioenergetics and viability. In this study, kidneys presenting no warm ischemia were tested in order to establish values in normal organs. The test could be easily integrated into the clinical environment and would not generate any additional delay into the transplantation clinical workflow.

The quantification of nanoparticles, particularly superparamagnetic iron oxide nanoparticles (SPIONs), both in vitro and in vivo has become highly important in recent years. Some methods, such as induced coupled plasma (ICP) spectroscopy and UV-visible chemical titration using Prussian Blue (PB), already exist however they consist of the titration of the whole iron content. These standard methods need sample preparations leading to their destruction and long measurement time. In this study, we used magnetic susceptibility measurements (MSM) to titrate the concentration and biodistribution of magnetic particles in the organs of rats. The advantages of the MSM SPION quantification technique are presented and compared to widely used methods of iron oxide titration such as ICP and PB UV-visible titration. We have demonstrated that MSM is a simpler, faster (1 second per measurement), more reproducible and highly sensitive technique for SPION detection with minimal detection around 2 μgFe mL(-1) without being influenced by neither the SPION coating nor their surrounding environment. Moreover, MSM is a more robust method as it is not affected by endogenous iron facilitating the distinction of SPIONs (iron present as nanoparticles) from background iron in tissues. This advantage allows the decrease of control samples needed in biological studies. In conclusion, we have demonstrated that MSM is a standard method that can be easily setup to determine the biodistribution of SPIONs regardless of their environment.

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In this model, MRI of pretransplantation superparamagnetic iron oxide nanoparticle-labeled islet grafts allows timely diagnosis of immune rejection.

The purpose of this study was to investigate the influence of the fast gradient-recalled echo (GRE) sequence parameters on the contrast dynamic range and signal sensitivity, to optimize the magnetic resonance (MR) sequence for contrast media pharmacokinetic assessment. Effects of the fast low-angle shot (FLASH), Fast acquisition at steady rate (FAST), and radiofrequency-spoiled (RF)-FAST sequence parameters were studied in vitro. The FAST sequence had the highest sensitivity in low gadolinium (Gd) concentration. The FLASH and RF-FAST sequences had a larger contrast dynamic range, but the FLASH images contained side band artifacts. Increasing the flip angle to 90°r aised the sensitivity of the FAST sequence and the contrast dynamic range of the RF-FAST sequence. The shortest possible TE was optimal for both contrast dynamics and imaging time. TI had an influence on the sensitivity of the FAST sequence only for small acquisition matrices. This study indicates the optimal parameters for contrast dynamics (RF-FAST, 90°flip angle, shortest possible TE) and sensitivity (FAST, 90°flip angle, long TI eff ).