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1.
Magnetic Resonance Materials in Physics, Biology and Medicine - In this paper, we review the developments of 1H-MR spectroscopic imaging (MRSI) methods designed to investigate prostate cancer,... 相似文献
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Transmit/receive headcoil for optimal <Superscript>1</Superscript>H MR spectroscopy of the brain in paediatric patients at 3 T 总被引:1,自引:0,他引:1
Klomp DW van der Graaf M Willemsen MA van der Meulen YM Kentgens AP Heerschap A 《Magma (New York, N.Y.)》2004,17(1):1-4
1H magnetic resonance (MR) spectroscopy is a useful tool to obtain metabolic information from the brain in paediatric patients. To detect signals of metabolites at low concentrations or from small volumes, the signal-to-noise ratio (SNR) has to be optimized. The SNR can be increased by going to higher field strengths. However, this leads to higher spectral bandwidths, which increases the chemical shift artefact. Here we present a transmit/receive headcoil which is adapted to the dimensions of the paediatric head and enables PRESS localization with high radio-frequency (RF) bandwidths that minimize the chemical shift displacement to only 5%. In addition, since the pulse lengths are shorter with higher RF bandwidths, the echo time can be reduced to 10 ms improving SNR as well.Parts of this work have been presented at the European Society for Magnetic Resonance in Medicine and Biology in Rotterdam in 2003 相似文献
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Gambarota G Veltien A van Laarhoven H Philippens M Jonker A Mook OR Frederiks WM Heerschap A 《Magma (New York, N.Y.)》2004,17(3-6):281-287
The purpose of this study was to investigate the magnetic resonance imaging (MRI) characteristics of colon cancer metastases in rat liver at 7 T. A dedicated RF microstrip coil of novel design was built in order to increase the signal-to-noise ratio and, in combination with respiratory triggering, to minimize motion artifacts. T1- and T2-weighted MR imaging was performed to follow tumor growth. T1-weighted images provided a good anatomical delineation of the liver structure, while the best contrast between metastases and normal liver tissue was achieved with T2-weighted images.Measurements of T1 and T2 relaxation times were performed with inversion recovery FLASH and Carr–Purcell–Meiboom–Gill and inversion recovery FLASH imaging sequences, respectively, for quantitative MR characterization of metastases. Both the T1 and T2 of the metastases were significantly higher than those of normal liver tissue. Further, an increase in the T1 relaxation time of the metastases was observed with tumor growth. These findings suggest that quantitative in vivo MR characterization provides information on tumor development and possibly response to therapy, though additional studies are needed to elucidate the correlation between the changes in relaxation times and tumor microenvironment. 相似文献
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Magnetic Resonance Materials in Physics, Biology and Medicine - Molecular interactions in prostatic fluid are of biological interest and may affect MRI and MRS of the prostate. We investigated the... 相似文献
7.
Simonetti AW Melssen WJ van der Graaf M Postma GJ Heerschap A Buydens LM 《Analytical chemistry》2003,75(20):5352-5361
A new classification approach was developed to improve the noninvasive diagnosis of brain tumors. Within this approach, information is extracted from magnetic resonance imaging and spectroscopy data, from which the relative location and distribution of selected tumor classes in feature space can be calculated. This relative location and distribution is used to select the best information extraction procedure, to identify overlapping tumor classes, and to calculate probabilities of class membership. These probabilities are very important, since they provide information about the reliability of classification and might provide information about the heterogeneity of the tissue. Classification boundaries were calculated by setting thresholds for each investigated tumor class, which enabled the classification of new objects. Results on histopathologically determined tumors are excellent, demonstrated by spatial maps showing a high probability for the correctly identified tumor class and, moreover, low probabilities for other tumor classes. 相似文献
8.
Fuster-Garcia E Navarro C Vicente J Tortajada S García-Gómez JM Sáez C Calvar J Griffiths J Julià-Sapé M Howe FA Pujol J Peet AC Heerschap A Moreno-Torres A Martínez-Bisbal MC Martínez-Granados B Wesseling P Semmler W Capellades J Majós C Alberich-Bayarri A Capdevila A Monleón D Martí-Bonmatí L Arús C Celda B Robles M 《Magma (New York, N.Y.)》2011,24(1):35-42
Object
This study demonstrates that 3T SV-MRS data can be used with the currently available automatic brain tumour diagnostic classifiers which were trained on databases of 1.5T spectra. This will allow the existing large databases of 1.5T MRS data to be used for diagnostic classification of 3T spectra, and perhaps also the combination of 1.5T and 3T databases.Materials and methods
Brain tumour classifiers trained with 154 1.5T spectra to discriminate among high grade malignant tumours and common grade II glial tumours were evaluated with a subsequently-acquired set of 155 1.5T and 37 3T spectra. A similarity study between spectra and main brain tumour metabolite ratios for both field strengths (1.5T and 3T) was also performed.Results
Our results showed that classifiers trained with 1.5T samples had similar accuracy for both test datasets (0.87 ± 0.03 for 1.5T and 0.88 ± 0.03 for 3.0T). Moreover, non-significant differences were observed with most metabolite ratios and spectral patterns.Conclusion
These results encourage the use of existing classifiers based on 1.5T datasets for diagnosis with 3T 1H SV-MRS. The large 1.5T databases compiled throughout many years and the prediction models based on 1.5T acquisitions can therefore continue to be used with data from the new 3T instruments. 相似文献9.
Objective To explore the possibilities of proton spectroscopic imaging (1H-MRSI) of the human brain at 7 Tesla with adiabatic refocusing pulses.
Materials and methods A combination of conventional slice selective excitation and two pairs of slice selective adiabatic refocusing pulses (semi-LASER)
results in the formation of an echo from a localized volume. Depending on the used radio frequency (rf) coil efficiency and
available rf power, the duration of the adiabatic full passage pulses (AFPs) is adapted to enable echo times down to 50 ms
(head coil) or 30 ms (local surface coil).
Results An AFP duration of 5 ms with a corresponding bandwidth of 5.1 kHz resulted in a chemical shift displacement error of 23% over
3.8 ppm at 7T. Using a local surface coil and an echo time down to 30 ms, we detected not only the three main metabolites
(NAA, Cr and Cho), but also coupled signals from myo-inositol and glutamate/glutamine in spectra from 0.14 cc voxels with
linewidths down to 10 Hz in 10 min measurement time.
Conclusions The semi-LASER pulse sequence enables 1H-MRSI of the human brain at 7T for larger parts of the brain as well as small localized areas with both a high spectral and
spatial resolution.
Part of this work has been presented at the ISMRM-ESMRMB joint meeting in 2007 in Berlin, Germany, abstract number 43. 相似文献
10.
K Steeghs F Oerlemans A de Haan A Heerschap L Verdoodt M de Bie W Ruitenbeek A Benders C Jost J van Deursen P Tullson R Terjung P Jap W Jacob D Pette B Wieringa 《Canadian Metallurgical Quarterly》1998,184(1-2):183-194
We have blocked creatine kinase (CK) mediated phosphocreatine (PCr) <==> ATP transphosphorylation in mitochondria and cytosol of skeletal muscle by knocking out the genes for the mitochondrial (ScCKmit) and the cytosolic (M-CK) CK isoforms in mice. Animals which carry single or double mutations, if kept and tested under standard laboratory conditions, have surprisingly mild changes in muscle physiology. Strenuous ex vivo conditions were necessary to reveal that MM-CK absence in single and double mutants leads to a partial loss of tetanic force output. Single ScCKmit deficiency has no noticeable effects but in combination the mutations cause slowing of the relaxation rate. Importantly, our studies revealed that there is metabolic and cytoarchitectural adaptation to CK defects in energy metabolism. The effects involve mutation type-dependent alterations in the levels of AMP, IMP, glycogen and phosphomonoesters, changes in activity of metabolic enzymes like AMP-deaminase, alterations in mitochondrial volume and contractile protein (MHC isoform) profiles, and a hyperproliferation of the terminal cysternae of the SR (in tubular aggregates). This suggests that there is a compensatory resiliency of loss-of-function and redirection of flux distributions in the metabolic network for cellular energy in our mutants. 相似文献