Utility and safety of invasive (fractional flow reserve) and non-invasive (cardiac magnetic resonance imaging) diagnostic tests in patients with NSTEMI

A prospective randomised controlled clinical trial of treatment decisions informed by invasive functional testing of coronary artery disease severity compared with standard angiography-guided management was implemented in 350 patients with a recent non-ST elevation myocardial infarction (NSTEMI) admitted to 6 hospitals in the National Health Service. The main aims of this study were to examine the utility of both invasive fractional flow reserve (FFR) and non-invasive cardiac magnetic resonance imaging (MRI) amongst patients with a recent diagnosis of NSTEMI. In summary, the findings of this thesis are: (1) the use of FFR combined with intravenous adenosine was feasible and safe amongst patients with NSTEMI and has clinical utility; (2) there was discordance between the visual, angiographic estimation of lesion significance and FFR; (3). The use of FFR led to changes in treatment strategy and an increase in prescription of medical therapy in the short term compared with an angiographically guided strategy; (4) in the incidence of major adverse cardiac events (MACE) at 12 months follow up was similar in the two groups. Cardiac MRI was used in a subset of patients enrolled in two hospitals in the West of Scotland. T1 and T2 mapping methods were used to delineate territories of acute myocardial injury. T1 and T2 mapping were superior when compared with conventional T2-weighted dark blood imaging for estimation of the ischaemic area-at-risk (AAR) with less artifact in NSTEMI. There was poor correlation between the angiographic AAR and MRI methods of AAR estimation in patients with NSTEMI. FFR had a high accuracy at predicting inducible perfusion defects demonstrated on stress perfusion MRI. This thesis describes the largest randomized trial published to date specifically looking at the clinical utility of FFR in the NSTEMI population. We have provided evidence of the diagnostic and clinical utility of FFR in this group of patients and provide evidence to inform larger studies. This thesis also describes the largest ever MRI cohort, including with myocardial stress perfusion assessments, specifically looking at the NSTEMI population. We have demonstrated the diagnostic accuracy of FFR to predict reversible ischaemia as referenced to a non-invasive gold standard with MRI. This thesis has also shown the futility of using dark blood oedema imaging amongst all comer NSTEMI patients when compared to novel T1 and T2 mapping methods.

Characterization of first sorption cycle of white Portland cement by 1H NMR

The work carried out is focused on the exploration of processes occurring in cement materials during sorption cycles by using Nuclear Magnetic Resonance (NMR) relaxometry. Long (months) and short (days-weeks) sorption cycles of cement materials were explored. The long cycle consists of around 6 months of drying and re-wetting cement samples of different sizes and water-to-cement (w/c) ratios in a homemade relative humidity (RH) chamber. Short cycles were performed by drying samples of different sizes and w/c ratios in the oven at 60 ˚C and re-wetting underwater. Different NMR techniques, such as one- and two-dimensional relaxometry and solid-signal analyses, were used to study the samples. Firstly, by the interpretation of quasi-continuous distributions of T2 relaxation time, we demonstrated that some reversible and irreversible changes concerning smaller porosity happened during the first sorption cycle. Secondly, using 2D NMR and a new 2D NMR inversion algorithm we showed preliminary results on the cement T1-T2 maps. Data obtained during sorption processes indicated possible water exchange between different pore populations inside the cement samples. Thirdly, the solid structure of cement samples was qualitatively investigated with T1 measurements and, as far as we know, for the first time interpreted with the Pake-Doublet theory. Changes in the solid structure were observed. Precisely variations of the amount of Ettringite during drying/wetting were proposed to take place. Finally, a work on NMR single-sided equipment design for in situ cement investigation was shown. The multi-cubic-blocks magnet structure design was performed using different specific CAD software, and the magnetic fields generated by RF coils of different geometries were investigated using a customized Matlab script. The single-sided NMR instrument equipped with the designed single-sided magnet and coil was built by the ERICA partner company MR Solutions (Abingdon, UK), and the preliminary results resultsated the correctness of the developed design.

Magnetic Resonance Imaging-Derived biomarkers of Isocitrate-Dehydrogenase mutation in diffuse gliomas: a conventional MR and Diffusion Weighted Imaging study.

The introduction of molecular criteria into the classification of diffuse gliomas has added interesting practical implications to glioma management. This has created a new clinical need for correlating imaging characteristics with glioma genotypes, also known as radiogenomics or imaging genomics. Whilst many studies have primarily focused on the use of advanced magnetic resonance imaging (MRI) techniques for radiogenomics purposes, conventional MRI sequences still remain the reference point in the study and characterization of brain tumours. Moreover, a different approach may rely on diffusion-weighted imaging (DWI) usage, which is considered a “conventional” sequence in line with recently published directions on glioma imaging. In a non-invasive way, it can provide direct insight into the microscopic physical properties of tissues. Considering that Isocitrate-Dehydrogenase gene mutations may reflect alterations in metabolism, cellularity, and angiogenesis, which may manifest characteristic features on an MRI, the identification of specific MRI biomarkers could be of great interest in managing patients with brain gliomas. My study aimed to evaluate the presence of specific MRI-derived biomarkers of IDH molecular status through conventional MRI and DWI sequences.

Correlations between cardiac magnetic resonance and histologic findings in Anderson Fabry disease

ABSTRACT Background Cardiac magnetic resonance (CMR) has been shown as promising diagnostic tool in Anderson-Fabry disease (AFD) cardiomyopathy due to its ability to detect fat deposits through lower native T1 values. However no histological validation has been provided to date. Objectives To correlate CMR and histologic findings in different cardiac stages of AFD focusing on T1 mapping. Methods Fifteen AFD patients (49 years [IQR 39-63], 60% females) undergoing CMR (cines, native T1 and T2 mapping, LGE and post-contrast T1 imaging) and endomyocardial biopsy (EMB, n=11) or septal myectomy (n=4), were retrospectively evaluated. Tissue specimens were analyzed with light/electron microscopy and vacuolization amount calculated as percentages of vacuolated myocytes and vacuolated myocyte area (%VMA) through a quantitative histomorphometric color-based analysis. Results In patients without increased indexed left ventricular mass (LVMi) at CMR (67%), T1 fell as %VMA increased (r= -0.883; p<0.001), whereas no clear relationship was evident once increased LVMi occurred (r= -0.501; p=0.389). At least 45% of vacuolized myocytes and 10% of VMA were needed for low T1 to occur. %VMA positively correlate with maximal wall thickness (MWT, r=0.860, p<0.0001) and LVMi (r= 0.762; p<0.001). Increased MWT and LVMi were present with at least 45% and 80% of vacuolated myocytes, respectively, and 18% and 22% of VMA. Conclusions This study demonstrated an inverse correlation between native T1 and the vacuolization amount in patients without increased LVMi at CMR, providing a histological validation of low native T1 in AFD. Importantly, a significant vacuolization burden was needed before low T1 and left ventricle hypertrophy occurred.

Sargassum Filipendula Alginate From Brazil: Seasonal Influence And Characteristics.

The aim of this work is focused on the extraction and characterization of the Brazilian seaweed Sargassum filipendula alginate. Alginates obtained at different seasons were characterized by liquid state nuclear magnetic resonance spectroscopy and scanning electron microscopy. The alginate extraction efficiency was about 20%. Different seasons of the year and different stages in the life cycle of Sargassum sp. in southeastern Brazil influenced the M/G and, consequently, the technological properties of extracted alginates.

Intraventricular Mass Lesions At Magnetic Resonance Imaging: Iconographic Essay - Part 1.

The present essay is illustrated with magnetic resonance images obtained at the authors' institution over the past 15 years and discusses the main imaging findings of intraventricular tumor-like lesions (ependymoma, pilocytic astrocytoma, central neurocytoma, ganglioglioma, choroid plexus papilloma, primitive neuroectodermal tumors, meningioma, epidermoid tumor). Such lesions represent a subgroup of intracranial lesions with unique characteristics and some image patterns that may facilitate the differential diagnosis.

Intraventricular Mass Lesions At Magnetic Resonance Imaging: Iconographic Essay - Part 2.

The present essay is illustrated with magnetic resonance images obtained at the authors' institution over the past 15 years and discusses the main imaging findings of intraventricular tumor-like lesions (colloid cyst, oligodendroglioma, astroblastoma, lipoma, cavernoma) and of inflammatory/infectious lesions (neurocysticercosis and an atypical presentation of neurohistoplasmosis). Such lesions represent a subgroup of intracranial lesions with unique characteristics and some imaging patterns that may facilitate the differential diagnosis.

Orbitofrontal Cortex Volumes in Medication Naive Children with Major Depressive Disorder: A Magnetic Resonance Imaging Study

Objectives: Adults with major depressive disorder (MDD) are reported to have reduced orbitofrontal cortex (OFC) volumes, which could be related to decreased neuronal density. We conducted a study on medication naive children with MDD to determine whether abnormalities of OFC are present early in the illness course. Methods: Twenty seven medication naive pediatric Diagnostic and Statistical Manual of Mental Disorders, 4(th) edition (DSM-IV) MDD patients (mean age +/- SD = 14.4 +/- 2.2 years; 10 males) and 26 healthy controls (mean age +/- SD = 14.4 +/- 2.4 years; 12 males) underwent a 1.5T magnetic resonance imaging (MRI) with 3D spoiled gradient recalled acquisition. The OFC volumes were compared using analysis of covariance with age, gender, and total brain volume as covariates. Results: There was no significant difference in either total OFC volume or total gray matter OFC volume between MDD patients and healthy controls. Exploratory analysis revealed that patients had unexpectedly larger total right lateral (F = 4.2, df = 1, 48, p = 0.05) and right lateral gray matter (F = 4.6, df = 1, 48, p = 0.04) OFC volumes compared to healthy controls, but this finding was not significant following statistical correction for multiple comparisons. No other OFC subregions showed a significant difference. Conclusions: The lack of OFC volume abnormalities in pediatric MDD patients suggests the abnormalities previously reported for adults may develop later in life as a result of neural cell loss.

Free-standing urethane/urea elastomer films undoped and doped with ferro-nano-particles

We report on an experimental study of the structures presented by urethane/urea elastomeric films without and with ferromagnetic nanoparticles incorporated. The study is made by using the X-ray diffraction, nuclear magnetic resonance (NMR), optical, atomic and magnetic force (MFM) microscopy techniques, and mechanical assays. The structure of the elastomeric matrix is characterized by a distance of 0.46 nm between neighboring molecular segments, almost independent on the stretching applied. The shear casting performed in order to obtain the elastomeric films tends to orient the molecules parallel to the flow direction thus introducing anisotropy in the molecular network which is reflected on the values obtained for the orientational order parameter and its increase for the stretched films. In the case of nanoparticles-doped samples, the structure remains nearly unchanged although the local order parameter is clearly larger for the undoped films. NMR experiments evidence modifications in the molecular network local ordering. Micrometer size clusters were observed by MFM for even small concentration of magnetic particles.

The isotropic nuclear magnetic shielding constants of acetone in supercritical water: A sequential Monte Carlo/quantum mechanics study including solute polarization

The nuclear isotropic shielding constants sigma((17)O) and sigma((13)C) of the carbonyl bond of acetone in water at supercritical (P=340.2 atm and T=673 K) and normal water conditions have been studied theoretically using Monte Carlo simulation and quantum mechanics calculations based on the B3LYP/6-311++G(2d,2p) method. Statistically uncorrelated configurations have been obtained from Monte Carlo simulations with unpolarized and in-solution polarized solute. The results show that solvent effects on the shielding constants have a significant contribution of the electrostatic interactions and that quantitative estimates for solvent shifts of shielding constants can be obtained modeling the water molecules by point charges (electrostatic embedding). In supercritical water, there is a decrease in the magnitude of sigma((13)C) but a sizable increase in the magnitude of sigma((17)O) when compared with the results obtained in normal water. It is found that the influence of the solute polarization is mild in the supercritical regime but it is particularly important for sigma((17)O) in normal water and its shielding effect reflects the increase in the average number of hydrogen bonds between acetone and water. Changing the solvent environment from normal to supercritical water condition, the B3LYP/6-311++G(2d,2p) calculations on the statistically uncorrelated configurations sampled from the Monte Carlo simulation give a (13)C chemical shift of 11.7 +/- 0.6 ppm for polarized acetone in good agreement with the experimentally inferred result of 9-11 ppm. (C) 2008 American Institute of Physics.

Equivalence between Redfield- and master-equation approaches for a time-dependent quantum system and coherence control

We present a derivation of the Redfield formalism for treating the dissipative dynamics of a time-dependent quantum system coupled to a classical environment. We compare such a formalism with the master equation approach where the environments are treated quantum mechanically. Focusing on a time-dependent spin-1/2 system we demonstrate the equivalence between both approaches by showing that they lead to the same Bloch equations and, as a consequence, to the same characteristic times T(1) and T(2) (associated with the longitudinal and transverse relaxations, respectively). These characteristic times are shown to be related to the operator-sum representation and the equivalent phenomenological-operator approach. Finally, we present a protocol to circumvent the decoherence processes due to the loss of energy (and thus, associated with T(1)). To this end, we simply associate the time dependence of the quantum system to an easily achieved modulated frequency. A possible implementation of the protocol is also proposed in the context of nuclear magnetic resonance.

Chemical and in vitro study of the potential of 3-(aryl)-2-sulfanylpropenoic acids and their Zn(II) complexes as protective agents against cadmium toxicity

The free H(2)xspa ligands [xspa = pspa, Clpspa, tspa or fspa where p = 3-(phenyl), Clp = 3-(2-chlorophenyl), t = 3-(2-thienyl), f = 3-(2-furyl) and spa = 2-sulfanylpropenoato], their Zn(II) complexes of formula [HQ](2)[Zn(xspa)(2)] (HQ=diisopropylammonium) and the Cd(II) equivalents were prepared and characterized by elemental analysis and by IR, Raman and NMR ((1)H, (13)C) spectroscopy. X-Ray studies of the crystal structures of [HQ](2)[Zn(pspa)(2)], [HQ](2)[Zn(Clpspa)2], [HQ](2)[Zn(tspa)(2)] and [HQ](2)[Zn(fspa)(2)] show that the zinc atom is coordinated to two O atoms and two S atoms of the ligands in a distorted tetrahedral ZnO(2)S(2) environment. In the structures of [HQ](2)[Cd(pspa)(2)] and [HQ](2)[Cd(Clpspa)(2)] the cadmium atom is coordinated to three S atoms and two carboxylato O atoms of the ligands in a distorted trigonal bipyramidal environment. The interchange of ligands between Zn( II) and Cd( II) was studied by (113)Cd NMR spectroscopy. The in vitro protective effect of H(2)xspa and their Zn( II) complexes against Cd toxicity was investigated using the human hepatocarcinoma HepG2 cell line and the pig renal proximal tubule LLC-PK1 cell line. The incorporation of Zn( II) was found to be relevant in the case of H(2)pspa, with an increase observed in the cell viability of the LCC-PK1 cells with respect to the value for the free ligand.

Intermediate motions and dipolar couplings as studied by Lee-Goldburg cross-polarization NMR: Hartmann-Hahn matching profiles

In this article, we evaluate the use of simple Lee-Goldburg cross-polarization (LG-CP) NMR experiments for obtaining quantitative information of molecular motion in the intermediate regime. In particular, we introduce the measurement of Hartmann-Hahn matching profiles for the assessment of heteronuclear dipolar couplings as well as dynamics as a reliable and robust alternative to the more common analysis of build-up curves. We have carried out dynamic spin dynamics simulations in order to test the method's sensitivity to intermediate motion and address its limitations concerning possible experimental imperfections. We further demonstrate the successful use of simple theoretical concepts, most prominently Anderson-Weiss (AW) theory, to analyze the data. We further propose an alternative way to estimate activation energies of molecular motions, based upon the acquisition of only two LG-CP spectra per temperature at different temperatures. As experimental tests, molecular jumps in imidazole methyl sulfonate, trimethylsulfoxonium iodide, and bisphenol A polycarbonate were investigated with the new method.

Cement stabilization of runoff residuals: A study of stabilization/solidification of urban rainfall-runoff residuals in type 1 Portland cement by XRD and Si-29 NMR analysis

Urban rainfall-runoff residuals contain metals such as Cr, Zn, Cu, As, Pb and Cd and are thus reasonable candidates for treatment using Portland cement-based solidification-stabilization (S/S). This research is a study of S/S of urban storm water runoff solid residuals in Portland cement with quicklime and sodium bentonite additives. The solidified residuals were analyzed after 28 days of hydration time using X-ray powder diffraction (XRD) and solid-state Si-29 nuclear magnetic resonance (NMR) spectroscopy. X-ray diffraction (XRD) results indicate that the main cement hydration products are ettringite, calcium hydroxide and hydrated calcium silicates. Zinc hydroxide and lead and zinc silicates are also present due to the reactions of the waste compounds with the cement and its hydration products. Si-29 NMR analysis shows that the coarse fraction of the waste apparently does not interfere with cement hydration, but the fine fraction retards silica polymerization.

Influence of cerium (IV) ions on the mechanism of organosilane polymerization and on the improvement of its barrier properties

In this work, the effect of cerium (IV) ammonium nitrate (CAN) addition on the polymerization of bis-[triethoxysilyl]ethane (BTSE) film applied on carbon steel was studied. The electrochemical characterization of the films was carried out in 0.1 mol L(-1) NaCl solution by open-circuit potential measurements, anodic and cathodic polarization curves and electrochemical impedance spectroscopy (EIS). Morphological and chemical characterization were performed by atomic force microscopy (AFM), contact angle measurements, infrared-spectroscopy, nuclear magnetic resonance and thermogravimetric analysis. The results have clearly shown the improvement on the protective properties of the Ce(4+) modified film as a consequence of the formation of a more uniform and densely reticulated silane film. A mechanism is proposed to explain the accelerating role of Ce(4+) ions on the cross-linking of the silane layer. (C) 2008 Elsevier Ltd. All rights reserved.