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Proton Spectroscopy (proton + spectroscopy)
Selected AbstractsIn vivo proton spectroscopy without solvent suppressionCONCEPTS IN MAGNETIC RESONANCE, Issue 4 2001David B. Clayton Abstract In 1H MR spectroscopy of the human brain, it is common practice to suppress the solvent signal prior to acquisition. This reduces the large dynamic range which is otherwise required of the MR receiver and digitizer in order to detect the dilute metabolite resonances in the presence of the much larger water signal. However, complete solvent suppression is not always obtainable, particularly over large volumes and in superficial regions containing large susceptibility gradients. In this work, it demonstrated that modern commercial MR scanners possess the dynamic range necessary to adequately resolve the 1H metabolites in unsuppressed spectra. Moreover, a postacquisition method is presented which can completely remove the intact water signal and accurately quantitate the metabolite peaks. Preserving the water signal in in vivo spectroscopy has several useful benefits, such as providing a high signal-to-noise ratio internal concentration, frequency, and line shape reference. Comparison is made between suppressed and unsuppressed spectra from both a phantom and the human brain acquired at 4 T. © 2001 John Wiley & Sons, Inc. Concepts Magn Reson 13: 260,275, 2001 [source] Frontal lobe syndrome or adolescent-onset schizophrenia?ACTA PSYCHIATRICA SCANDINAVICA, Issue 5 2006A case report Objective:, To highlight the difficulties that abound in making a clinical distinction between early-onset schizophrenia (EOS) and juvenile frontal dementia early in the course of illness. Method:, Clinical information and data from investigations in single case was collated and reviewed. Results:, A 15-year-old girl was admitted to our psychiatric unit because of cognitive decline and formal thought disorder with echopraxia, echolalia and palilalia, and a lack of flexibility in the use of cognitive and motor strategies that culminated in psychosis. A single photon emission computerized tomography scan showed marked frontal lobe hypoperfusion; however, on proton spectroscopy there was no differential in N -acetyl aspartate levels. Conclusion:, Hypofrontality in EOS is well established and the association of frontal functional alterations, neuropsychological impairment and psychotic symptomatology is suggestive of frontal lobe prodrome that precedes the onset of psychosis. [source] Quantitative multivoxel proton spectroscopy of the brain in developmental delayJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2009Krijn T. Verbruggen MD Abstract Purpose To assess whether proton MR spectroscopy of the brain in children with developmental delay reveals a consistent pattern of abnormalities. Materials and Methods Eighty-eight patients (median age, 4.6 years; interquartile range, 3.1,8.1 years) with unexplained developmental delay, were compared with 48 normally developing age-matched controls. Patients and controls were assigned to five age-groups. Multivoxel MR spectroscopy was performed on a volume of interest superior to the lateral ventricles. The relative levels of choline, creatine, N-acetyl aspartate, and glutamate/glutamine in 24 voxels containing white matter and 12 voxels containing gray matter were quantified in an operator-independent manner and expressed in proportion to the total metabolite peak area in the volume of interest. Results White matter choline in DD showed less decrease with age. Mean choline levels, compared with mean control levels, increased from 99 to 111% with increasing age. This was statistically significant in the highest age groups (P = 0.015 [7 < yr , 12.8] and P = 0.039 [12.8 < yr]). Other metabolites did not show clear alterations. Conclusion Proton MR spectroscopy in a group of patients with unexplained DD shows small differences in the metabolite pattern, compared with normally developing controls, that is, higher choline in the white matter. The pathophysiological origin and significance may relate to myelination and maturation of the white matter. J. Magn. Reson. Imaging 2009;30:716,721. © 2009 Wiley-Liss, Inc. [source] Diffusion-weighted spectroscopy: A novel approach to determine macromolecule resonances in short-echo time 1H-MRSMAGNETIC RESONANCE IN MEDICINE, Issue 4 2010N. Kunz Abstract Quantification of short-echo time proton magnetic resonance spectroscopy results in >18 metabolite concentrations (neurochemical profile). Their quantification accuracy depends on the assessment of the contribution of macromolecule (MM) resonances, previously experimentally achieved by exploiting the several fold difference in T1. To minimize effects of heterogeneities in metabolites T1, the aim of the study was to assess MM signal contributions by combining inversion recovery (IR) and diffusion-weighted proton spectroscopy at high-magnetic field (14.1 T) and short echo time (=8 msec) in the rat brain. IR combined with diffusion weighting experiments (with ,/, = 1.5/200 msec and b -value = 11.8 msec/,m2) showed that the metabolite nulled spectrum (inversion time = 740 msec) was affected by residuals attributed to creatine, inositol, taurine, choline, N -acetylaspartate as well as glutamine and glutamate. While the metabolite residuals were significantly attenuated by 50%, the MM signals were almost not affected (<8%). The combination of metabolite-nulled IR spectra with diffusion weighting allows a specific characterization of MM resonances with minimal metabolite signal contributions and is expected to lead to a more precise quantification of the neurochemical profile. Magn Reson Med, 2010. © 2010 Wiley-Liss, Inc. [source] Navigator gating and volume tracking for double-triggered cardiac proton spectroscopy at 3 TeslaMAGNETIC RESONANCE IN MEDICINE, Issue 6 2004Michael Schär Abstract Respiratory motion compensation based on navigator echoes for double-triggered cardiac proton spectroscopy at 3.0T is presented. The navigators measure the displacement of the liver,lung interface during free breathing. This information allows for double triggering on a defined window within the respiratory cycle and on a defined trigger delay after the R-wave based on the ECG. Furthermore, it allows the excitation volume to be shifted by the determined respiratory displacement within the defined window in real-time (volume tracking). Static and motion phantom experiments were performed in this study, and it was demonstrated that volume tracking permits the suppression of signal from tissue next to the localized volume. However, triggering on a defined respiratory position is still necessary to achieve high spectral quality, because shimming and water suppression calibration are only optimal for a small window of the respiratory cycle. Single-volume spectra obtained in the myocardial septum of healthy subjects are presented. Magn Reson Med 51:1091,1095, 2004. © 2004 Wiley-Liss, Inc. [source] MRI of muscular fatMAGNETIC RESONANCE IN MEDICINE, Issue 4 2002Fritz Schick Abstract An MRI technique with high selectivity and sensitivity to the signal components in the chemical shift range of methylene and methyl protons of fatty acids has been developed for noninvasive assessment of muscular fat in vivo. A spoiled gradient-echo sequence with spatial-spectral excitation by six equidistant pulses with 2°-(,9°)-17°-(,17°)-9°-(,2°) and a multi-echo train (TE = 16, 36, 56, 76, 96, and 116 ms) allowed a series of images to be recorded with a receiver bandwidth of 78 Hz per pixel. SIs from phantoms with lipid contents between 0.1% and 100% were compared to those from pure water. Thirty healthy volunteers underwent fat-selective imaging of their lower leg, and parallel localized proton spectroscopy of the tibialis anterior and the soleus muscle by a single-voxel stimulated echo acquisition mode (STEAM) technique (TR = 2 s, TE = 10 ms, TM = 15 ms). Results show a high correlation (r = 0.91) between fat imaging and the spectroscopic approach in the soleus muscle, considering the percentage total fat content of musculature. The correlation coefficient was clearly lower (r = 0.55) in the tibialis anterior muscle due to signal contaminations from adjacent subcutaneous fat in the images, inhomogeneous fat distribution, and generally lower lipid content in this muscle. Applications of the new imaging technique showed marked intra- and interindividual variability in the spatial distribution of lipids in the musculature of the lower leg. No significant correlation of the muscular fat with the thickness of the subcutaneous fat layer was found. In addition, the body mass index does not appear to determine muscular fat content, except in very obese cases. Magn Reson Med 47:720,727, 2002. © 2002 Wiley-Liss, Inc. [source] Monitoring cytotoxic tumour treatment response by diffusion magnetic resonance imaging and proton spectroscopyNMR IN BIOMEDICINE, Issue 1 2002Risto A. Kauppinen Abstract Exposure of tumours to anti-cancer drugs, gene or radiation therapy consistently leads to an increase in water diffusion in the cases expressing favourable treatment response. The diffusion change coincides cytotoxic cell eradication and precedes volume reduction in drug or gene therapy-treated experimental tumours. Interestingly, the recent studies from human brain tumour patients undergoing chemotherapy show similar behaviour of diffusion, suggesting important application for MRI in patient management. In this review observations from diffusion MRI and MRS in the tumours during cytotoxic treatment are summarized and the cellular mechanisms affecting molecular mobility are discussed in the light of tissue microenvironmental and microdynamic changes. Copyright © 2002 John Wiley & Sons, Ltd. 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