Phase-rotated MR spectroscopy using dual-PRESS: theory and application in human brain

Phase-rotation spectroscopic acquisition is inherently different from the popular signal-averaging method. Phase-rotation will be described theoretically and experimentally in this article. Traditionally, a single echo is acquired in a PRESS or STEAM sequence at a particular TE. If a long-TE spectrum is desired, then another echo is usually acquired at a longer echo time. We here propose a method by which a pair of echoes, at short-TE and a long-TE, are acquired in one experiment, thus saving 50% of total acquisition time without significant sacrifice of spectral quality. The phase-rotation approach has been implemented with the proposed method. An additional benefit of the proposed Dual-PRESS method, is that it gives an insight into the transverse relaxation time constant, T2, for the various metabolites. The Dual-PRESS method is applied in phantom and in-vivo

Phytotoxicity and cytogenotoxicity of water and sediment of urban stream in bioassay with Lactuca sativa

The aim of this study was to evaluate the spatial and temporal influence of the phytotoxicity and cytogenotoxicity of water and sediment of urban stream on the germination and initial growth of Lactuca sativa. Samples were collected from water and sediment at five sites of the Pântano Stream (Alfenas, Minas Gerais) during the period from October 2010 to July 2011. The concentrations of the metals Cd, Pb and Zn were quantified. Moreover, phytotoxicity and cytogenotoxicity were tested with samples of water and aqueous extracts of sediments. The evaluated end points were the germination rate, root length, fresh and dry weight, mitotic index and frequency of chromosomal abnormalities. Higher levels of Cd and Pb were verified in water samples collected during the rainy months. Water and sediment showed phytotoxic effect on germination, fresh weight and dry weight of Lactuca sativa. Root length was stimulated and only samples of water reduced the mitotic index. Significant temporal variation related to rainfall was observed only for phytotoxicity tests.Objetivou-se, com este trabalho, avaliar a influência espacial e temporal da fitotoxicidade e da citogenotoxicidade da água e do sedimento de córrego urbano quanto às características germinativas e de crescimento inicial de Lactuca sativa. Amostras de água e de sedimento foram coletadas em 5 pontos do Córrego do Pântano (Alfenas, Minas Gerais), no período de outubro de 2010 a julho de 2011 e as concentrações dos metais Cd, Pb e Zn foram quantificadas. Os ensaios de fitotoxicidade e de citogenotoxicidade foram realizados com as amostras de água e extratos aquosos dos sedimentos. Os parâmetros avaliados foram taxa de germinação, comprimento de raízes, biomassa fresca e seca, índice mitótico e a frequência de anormalidades cromossômicas. Constataram-se maiores concentrações de Cd e Pb nas amostras de água coletadas nos meses com a ocorrência de precipitações pluviométricas. Água e sedimento apresentaram efeito fitotóxico sobre germinação, biomassa fresca e seca de Lactuca sativa. O comprimento de raízes foi estimulado e apenas as amostras de água reduziram o índice mitótico. Evidenciou-se, também, variação temporal significativa relacionada com o regime pluviométrico apenas para o teste de fitotoxicidade.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)UNIFAL Instituto de Ciências da NaturezaUNIFAL Instituto de Ciências ExatasUNIFESPUNIFESPSciEL

Changes in the neurochemistry of athletes with repetitive brain trauma: preliminary results using localized correlated spectroscopy

Introduction: The goal was to identify which neurochemicals differ in professional athletes with repetitive brain trauma (RBT) when compared to healthy controls using a relatively new technology, in vivo Localized COrrelated SpectroscopY (L-COSY). Methods: To achieve this, L-COSY was used to examine five former professional male athletes with 11 to 28 years of exposure to contact sports. Each athlete who had had multiple symptomatic concussions and repetitive sub concussive trauma during their career was assessed by an experienced neuropsychologist. All athletes had clinical symptoms including headaches, memory loss, confusion, impaired judgment, impulse control problems, aggression, and depression. Five healthy men, age and weight matched to the athlete cohort and with no history of brain trauma, were recruited as controls. Data were collected from the posterior cingulate gyrus using a 3 T clinical magnetic resonance scanner equipped with a 32 channel head coil. Results: The variation of the method was calculated by repeated examination of a healthy control and phantom and found to be 10% and 5%, respectively, or less. The L-COSY measured large and statistically significant differences (P ≤0.05), between healthy controls and those athletes with RBT. Men with RBT showed higher levels of glutamine/glutamate (31%), choline (65%), fucosylated molecules (60%) and phenylalanine (46%). The results were evaluated and the sample size of five found to achieve a significance level P = 0.05 and a power of 90%. Differences in N-acetyl aspartate and myo-inositol between RBT and controls were small and were not statistically significance. Conclusions: A study of a small cohort of professional athletes, with a history of RBT and symptoms of chronic traumatic encephalopathy when compared with healthy controls using 2D L-COSY, showed elevations in brain glutamate/glutamine and choline as recorded previously for early traumatic brain injury. For the first time increases in phenylalanine and fucose are recorded in the brains of athletes with RBT. Larger studies utilizing the L-COSY method may offer an in-life method of diagnosis and personalized approach for monitoring the acute effects of mild traumatic brain injury and the chronic effects of RBT

Methodological consensus on clinical proton MRS of the brain: Review and recommendations

© 2019 International Society for Magnetic Resonance in Medicine Proton MRS (1H MRS) provides noninvasive, quantitative metabolite profiles of tissue and has been shown to aid the clinical management of several brain diseases. Although most modern clinical MR scanners support MRS capabilities, routine use is largely restricted to specialized centers with good access to MR research support. Widespread adoption has been slow for several reasons, and technical challenges toward obtaining reliable good-quality results have been identified as a contributing factor. Considerable progress has been made by the research community to address many of these challenges, and in this paper a consensus is presented on deficiencies in widely available MRS methodology and validated improvements that are currently in routine use at several clinical research institutions. In particular, the localization error for the PRESS localization sequence was found to be unacceptably high at 3 T, and use of the semi-adiabatic localization by adiabatic selective refocusing sequence is a recommended solution. Incorporation of simulated metabolite basis sets into analysis routines is recommended for reliably capturing the full spectral detail available from short TE acquisitions. In addition, the importance of achieving a highly homogenous static magnetic field (B0) in the acquisition region is emphasized, and the limitations of current methods and hardware are discussed. Most recommendations require only software improvements, greatly enhancing the capabilities of clinical MRS on existing hardware. Implementation of these recommendations should strengthen current clinical applications and advance progress toward developing and validating new MRS biomarkers for clinical use

Mountford, Carolyn E.: Spectroscopy in the clinic too good to be true?

The history of the development, in Australia, of one and two dimensional MR spectroscopy to study the chemical changes associated with tumor development and progression in cells, biopsies, and in vivo is discussed. Pathologies not discernable by light microscopy but discernable by MR spectroscopy were recorded in these early studies. The early history of neurospectroscopy applied to chronic pain; preoperative diagnosis of ovarian disease; and the analysis of MR spectroscopy data by pattern recognition methods are described

Two-dimensional magnetic resonance spectroscopy on biopsy and in vivo

Two-dimensional (2D) magnetic resonance spectroscopy (MRS) allows those resonances that are composite in a one-dimensional spectrum, to be examined usually as individual components, in a second frequency. The 2D method has allowed the assignment of molecules that are both diagnostic and prognostic, in the spectra from human cells, biopsies and stool. The acquisition and post-processing parameters required attention due to the very wide range of relaxation and J-coupling values present in these specimens. 2D MRS data can also be collected in vivo. Again the acquisition sequences needed to be developed, to facilitate the localization at the lower field strengths available, for in vivo studies for brain, breast, prostate, muscle and bone marrow. In vivo 2D MRS is in its infancy but promises to be a valuable tool in the future for monitoring disease and response to therapy, particularly using the higher field strength clinical magnets now available

Adiabatic localized correlation spectroscopy (AL-COSY): application in muscle and brain

Purpose To describe an enhanced version of a localized correlation spectroscopy (L-COSY) by introducing adiabatic radiofrequency (RF) pulses for localization in two dimensions. Adiabatic pulses will improve slice selection profile and reduce chemical shift artifacts. Optimized Mao and adiabatic hyperbolic secant pulses are tested in vivo. Materials and Methods: Region of interest is localized by a 90° nonselective adiabatic RF pulse followed by two pairs of adiabatic RF pulses and a terminal 90° RF sinc pulse. Slice profiles for both refocusing pulses and chemical shift artifacts are measured in a water–oil phantom for L-COSY and AL-COSY. In vivo results of both COSY sequences are shown from muscle and brain on a 3 Tesla (T) scanner. Results Chemical shift artifacts were reduced with AL-COSY compared with L-COSY. Slice profiles of adiabatic pulses were found to be sharper and more symmetrical than those of traditional Mao pulses. One-dimensional (1D) phantom studies showed longer T2 values using AL-COSY sequence. Comparison of 2D spectra obtained revealed spectroscopic peak volume improvements in AL-COSY and less residual water. In vivo 1D comparison showed more inphase and sharper peaks in AL-COSY spectrum. Conclusion The AL-COSY sequence is an improved sequence due to sharper slice selection profiles, reduction of chemical shift artifacts, peak volume improvements in 2D techniques, and less J-modulation

Proton magnetic resonance spectroscopy of lymphocytes: An historical perspective

Proton magnetic resonance spectroscopy can be used to elucidate alterations to cellular chemistry associated with specific biological functions. It became apparent that this type of information was present in the magnetic resonance spectra from intact viable lymphocytes in the late 1970s. It was not until the 1980s, however, that one-dimensional multipulse sequences were used to filter the large signal contributions from water and fat, which had until then masked weaker signals from other molecules. When this technology was combined with two-dimensional spectroscopy, unambiguous assignment of the biologically relevant chemical species became possible. In vitro activated, stimulated, transformed, and malignant lymphocytes, as well as embryonic fibroblasts and malignant cells of epithelial origin, all gave rise to a strong triglyceride spectrum and resonances from a multitude of cellular metabolites. Two-dimensional spectroscopy and the analyses of highly purified membranes determined that the triglyceride signals originated, at least in part, from the plasma membrane. Based on physicochemical data, a new model for the structural arrangement of plasma membrane lipid in these cells was proposed. While differences exist between the proton magnetic resonance spectra of stimulated lymphocytes and malignant cells in vitro, they share a high-resolution lipid spectrum. In tissue, however, the presence of activated lymphocytes does not always produce the lipid spectrum, particularly in the vicinity of tumors

Breast MR imagingat 3.0T

It was reported in the June 2006 issue of Radiology (1) that the "differential diagnosis of enhancing lesions was possible with higher diagnostic confidence" at 3.0-T magnetic resonance (MR) imaging. Next, a two-part review in the August and September 2007 issues (2,3) indicated breast imaging was robust. A September 2007 letter (4) contradicted the initial report by stating that "due to spatial B1 inhomogeneities across the field view [FOV], enhancement of lesions may be reduced to a variable degree" and "false-negative breast MR imaging studies at 3.0 T are conceivable."..