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Nondestructive studies of physiological processes in agronomic products require increasingly higher spatial and temporal resolutions. Nuclear Magnetic Resonance (NMR) imaging is a non-invasive technique providing physiological and morphological information on biological tissues. The aim of this study was to design a robust and accurate quantitative measurement method based on NMR imaging combined with contrast agent (CA) for mapping and quantifying water transport in growing cherry tomato fruits. A multiple flip-angle Spoiled Gradient Echo (SGE) imaging sequence was used to evaluate the intrinsic parameters maps M0 and T1 of the fruit tissues. Water transport and paths flow were monitored using Gd(3+)/[Fe(CN)6](3-)/D-mannitol nanoparticles as a tracer. This dynamic study was carried out using a compartmental modeling. The CA was preferentially accumulated in the surrounding tissues of columella and in the seed envelopes. The total quantities and the average volume flow of water estimated are: 198 mg, 1.76 mm(3)/h for the columella and 326 mg, 2.91 mm(3)/h for the seed envelopes. We demonstrate in this paper that the NMR imaging technique coupled with efficient and biocompatible CA in physiological medium has the potential to become a major tool in plant physiology research., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Objective: To improve diagnosis of early Alzheimer's disease (AD), i.e., prodromal AD, by an automated quantitative tool combining brain perfusion single-photon emission computed tomography (SPECT) images and memory tests scores in order to be applied in clinical practice., Patients and Methods: In this prospective, longitudinal, multi-centric study, a baseline (99m)Tc-ECD perfusion SPECT was performed in 83 patients with memory complaint and mild cognitive impairment (MCI). After a 3-year follow-up, 11 patients progressed to Alzheimer's disease (MCI-AD group), and 72 patients remained stable (MCI-S group), including 1 patient who developed mild vascular cognitive impairment. After comparison between the MCI-S and MCI-AD groups with a voxel-based approach, region masks were extracted from the statistically significant clusters and used alone or in combination with Free and Cued Selective Reminding Test (FCSRT) scores for the subject's categorization using linear discriminant analysis. Results were validated using the leave-one-out cross-validation method., Results: Right parietal and hippocampal perfusion was significantly (p<0.05, corrected) decreased in the MCI-AD group as compared to the MCI-S group. The patients' classification in the MCI group using the mean activity in right and left parietal cortex and hippocampus yielded a sensitivity, specificity, and accuracy of 82%, 90%, and 89%, respectively. Combination of SPECT results and FCSRT free recall scores increased specificity to 93%., Conclusion: The combination of an automated quantitative tool for brain perfusion SPECT images and memory test scores was able to distinguish, in a group of amnestic MCI, patients at an early stage of AD from patients with stable MCI., (Copyright © 2009 Elsevier Inc. All rights reserved.)

Deep Brain Stimulation is an effective treatment of generalized dystonia. Optimal stimulation parameters vary between patients. This article investigates the influence of electrical brain impedance and delivered current on the brain response to stimulation. Twenty-four patients were bilaterally stimulated in the globus pallidus internus through two implanted four-contact electrodes. The variation of brain impedance and current measurements was correlated with stimulation parameters, time course, and clinical outcome. When a contact was activated, a statistically significant and reversible decrease of brain impedance was found. Impedance and current values and their variations with time significantly differed between patients. The absolute impedance did not significantly correlate with the final outcome. We conclude that the reversible decrease of impedance reflects an adaptive long-term mechanism, which could be due to a plasticity phenomenon, but has no prognostic value. Impedance and current measurements give new complementary information for parameter adjustment and trouble shooting and should therefore be included in all patients' follow-up.

A solution for discrete multi-exponential analysis of T(2) relaxation decay curves obtained in current multi-echo imaging protocol conditions is described. We propose a preprocessing step to improve the signal-to-noise ratio and thus lower the signal-to-noise ratio threshold from which a high percentage of true multi-exponential detection is detected. It consists of a multispectral nonlinear edge-preserving filter that takes into account the signal-dependent Rician distribution of noise affecting magnitude MR images. Discrete multi-exponential decomposition, which requires no a priori knowledge, is performed by a non-linear least-squares procedure initialized with estimates obtained from a total least-squares linear prediction algorithm. This approach was validated and optimized experimentally on simulated data sets of normal human brains.

Four different MRI techniques of volumetric evaluation were applied in 10 healthy females and compared. The results have shown that not all techniques were interchangeable, but that the results of two groups of methods are not statistically different.

Magnetic resonance imaging has been used to characterize muscle fiber types. Here, T1 and T2 values were determined in pure slow-twitch and fast-twitch rabbit muscles and in rabbit muscles with mixed fiber types. The muscles with high proportions of oxidative slow-twitch fibers had higher T2 values than the others. Echo time, orientation of muscle fibers in B0, and moving spins had no effect on relaxation parameters. The results are discussed in terms of slow myosin isoform content and oxidative metabolism.

The dynamics of water in postmortem muscle were studied by magnetic resonance microscopy (MRM). Rabbit muscles were arterially injected with 3 and 5 M NaCl brine. T2 and diffusion mapping were performed during the onset of rigor mortis. A wide spread of T2 values and widely differing postmortem evolutions were observed for injected muscles, whereas T2 was spatially homogeneous for intact muscle. Also, highly variable spatial distribution of diffusion coefficients along (Dz) and across (Dx) the muscle fibers was observed and diffusion anisotropy Dz/Dx) was less marked in injected muscles. The results indicate heterogeneity of brine distribution far from the injection site soon after injection. The postmortem evolution of the parameters is discussed in terms of structural changes induced by brine injection. MRM provides insight into how water dynamics respond to different NaCl concentrations inside muscle.

The first part, after a brief historical reminder, gives an oversimplified and non-rigorous approach to the Nuclear Magnetic Resonance (NMR) phenomenon; this "physical" introduction leads the clinician to know the essential about the spectral and imaging techniques in NMR, just to understand what is done... The second part of this paper shows some medical applications of these two aspects of NMR, with help of some examples, taken from the literature, according to what is concerned with endocrinology. Pure bio chemical applications (enzymology), or those concerning isolated (and perfused) organs, or living animals, and even human beings, are numerous and complementary, and there is no doubt that the applications of NMR technologies to medicine will know a promising future...