Magnetic resonance imaging of glutamate

Glutamate, a major neurotransmitter in the brain, shows a pH- and concentration-dependent chemical exchange saturation transfer effect (GluCEST) between its amine group and bulk water, with potential for in vivo imaging by nuclear magnetic resonance. GluCEST asymmetry is observed ～3 p.p.m. downfield from bulk water. Middle cerebral artery occlusion in the rat brain resulted in an ～100% elevation of GluCEST in the ipsilateral side compared with the contralateral side, predominantly owing to pH changes. In a rat brain tumor model with blood-brain barrier disruption, intravenous glutamate injection resulted in a clear elevation of GluCEST and a similar increase in the proton magnetic resonance spectroscopy signal of glutamate. GluCEST maps from healthy human brain were also obtained. These results demonstrate the feasibility of using GluCEST for mapping relative changes in glutamate concentration, as well as pH, in vivo. Contributions from other brain metabolites to the GluCEST effect are also discussed.     

Magnetic resonance imaging in patients with ICDs and pacemakers

Magnetic resonance (MR) imaging has unparalleled soft-tissue imaging capabilities. The presence of devices such as pacemakers and implantable cardioverter/defibrillators (ICDs), however, is historically considered a contraindication to MR imaging. These devices are now smaller, with less magnetic material and improved electromagnetic interference protection. This review summarizes the potential hazards of the device-MR environment interaction, and presents updated information regarding in-vivo and in-vitro experiments. Recent reports on patients with implantable pacemakers and ICDs who underwent MR scan shows that under certain conditions patients with these implanted systems may benefit from this imaging modality. The data presented suggests that certain modern pacemaker and ICD systems may indeed be MR safe. This may have major clinical implications on current imaging practice.     

Magnetic resonance imaging in personalized medicine

正Continued biomedical advances and increased demands on quality health care have led to a new era of personalized medicine—a concept of medicine that uses specific information to an individual to help diagnose disease,plan treatment,assess treatment efficacy,and/or predict prognosis.This concept has evolved from the idea of"patient-centered care",which intends to shift the focus of health care from diseases to patients(Abujudeh et al.,2016).Medical imaging is essential in the practice of modern medicine,and its role in personalized medicine has never been greater.In particular,magnetic resonance(MR)     

Magnetic resonance imaging of the vomeronasal organ

The vomeronasal organ of mice and frogs was studied by highspatial resolution magnetic resonance imaging. By this techniquethe presence of material in the vomeronasal lumen can be evidencedin vivo.     

Magnetic resonance imaging of self-assembled biomaterial scaffolds

Current interest in biomaterials for tissue engineering and drug delivery applications have spurred research into self-assembling peptide amphiphiles (PAs). Nanofiber networks formed from self-assembling PAs can be used as biomaterial scaffolds with the advantage of specificity by the incorporation of peptide-epitopes. Imaging the materials noninvasively will give information as to their fate in vivo. We report here the synthesis and in vitro MR images of self-assembling peptide amphiphile contrast agents (PACAs) that form nanofibers. At 400 MHz using a 0.1 mM Gd(III) conjugate of the PA we observed a T(1) three times that of a control gel. The PA derivative was doped into various epitope bearing PA solutions and upon gelling resulted in a homogeneous biomaterial as imaged by MRI.     

Magnetic resonance imaging of total body fat

In this study we assessed different magneticresonance imaging (MRI) scanning regimes and examined some of theassumptions commonly made for measuring body fat content by MRI. Wholebody MRI was used to quantify and study different body fat depots in 67 women. The whole body MRI results showed that there was a significant variation in the percentage of total internal, as well as visceral, adipose tissue across a range of adiposity, which could not be predicted from total body fat and/or subcutaneous fat.Furthermore, variation in the amount of total, subcutaneous, andvisceral adipose tissue was not related to standard anthropometricmeasurements such as skinfold measurements, body mass index, andwaist-to-hip ratio. Finally, we show for the first time subjects with apercent body fat close to the theoretical maximum (68%). This studydemonstrates that the large variation in individual internal fatcontent cannot be predicted from either indirect methods or directimaging techniques, such as MRI or computed tomography, on the basis ofa single-slice sampling strategy.

     

Magnetic fields after translation in Escherichia coli

Quantitative two-dimensional gel electrophoresis of proteins in E. coli exposed for 60 min to weak, pulsed magnetic fields (1.5 mT peak) show that numerous proteins are both increased and decreased by a factor of 2 or more. An increase in the levels of two proteins, the a subunit of DNA-dependent RNA polymerase and NusA, was confirmed by Western blot analysis. © 1994 Wiley-Liss, Inc.     

Structure of an Escherichia coli bacterial suspension]

The structure of bacterial suspensions of Escherichia coli M-17 at the counting concentrations of the cells 10(7), 10(8), 10(9) i/ml and in the temperature range of (18-50) degrees C has been investigated by means of orientational conductometric, electron microscopic and UV-spectroscopic methods. On the basis of experimental relationships of the anisotropy of suspensions electric conductivity upon the intensity of a sinusoidal electric field and relaxation of anisotropy after switching off the field the function of the distribution of bacteria with respect to their sizes was evaluated at different temperatures and concentrations. The conductometric function of bacteria distribution is in a good agreement with the analogous function obtained with the help of the electron microscope. In accordance with the functions the suspension of E. coli contained three kinds of cells: high electronic density, low electronic density bacteria and bacteria aggregates. Relative amounts of every kind of bacteria depended on temperature and concentration of cells. The minimum of bacteria aggregates and maximum of low electronic density cells were obtained in the temperature range of (32-42) degrees C. This fact could be explained by the activation of the transport membrane systems in this temperature range. This hypothesis was confirmed by the UV-spectroscopic method.     

Magnetic resonance imaging in patients with cardiac implantable electronic devices

In recent years the prevalence of implantation of a cardiac implantable electronic device (CIED) has increased due to expanding implantation indications and prolonged life expectancy. Diagnostic strategies increasingly employ magnetic resonance imaging (MRI) to aid therapeutic strategies. In earlier guidelines, MRI was contra-indicated in patients with CIEDs, mainly due to previous reports of severe complications. With the development of MRI-conditional CIEDs and recent evidence concerning non-MRI-conditional CIEDs, MRIs in CIED patients can be safely performed in many hospitals.However, there are several questions that need to be addressed. Which patients can we scan? How can the scans be performed safely? And last but not least, can cardiac MRI provide diagnostic yield in patients with CIEDs?Current European guidelines are rather outdated and vague about patient selection and practical issues. There are national guidelines on this topic but several issues need extra attention and those are addressed in this point of view. It is important to create an environment with proper patient selection without unnecessary MRI scans in CIED patients, but also without unnecessary fear of complications, preventing access to MRI in patients who can benefit from this powerful diagnostic tool.     

Magnetic resonance imaging for prostate cancer radiotherapy

For radiotherapy of prostate cancer, MRI is used increasingly for delineation of the prostate gland. For focal treatment of low-risk prostate cancer or focal dose escalation for intermediate and high-risk cancer, delineation of the tumor is also required. While multi-parametric MRI is well established for detection of tumors and for staging of the disease, delineation of the tumor inside the prostate is not common practice.Guidelines, such as the PI-RADS classification, exist for tumor detection and staging, but no such guidelines are available for tumor delineation. Indeed, interobserver studies show substantial variation in tumor contours. Computer-aided tumor detection and delineation may help improve the robustness of the interpretation of multi-parametric MRI data. Comparing the performance of an earlier developed model for tumor segmentation with expert delineations, we found a significant correlation between tumor probability in a voxel and the number of experts identifying this voxel as tumor. This suggests that the model agrees with ‘the wisdom of the crowd’, and thus could serve as a reference for individual physicians in their decision making.With multi-parametric MRI it becomes feasible to revisit the GTV-CTV concept in radiotherapy of prostate cancer. While detection of index lesions is quite reliable, contouring variability and the low sensitivity to small lesions suggest that the remainder of the prostate should be treated as CTV. Clinical trials that investigate the options for dose differentiation, for example with dose escalation to the visible tumor or dose reduction to the CTV, are therefore warranted.