Characterizing Brain Tumors by MRS

Howe, Franklyn A.; Peet, Andrew C.

doi:10.1002/9780470034590.emrstm1425

Cited by 2 publications

(3 citation statements)

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“…Since the biochemical environment of tissue is dramatically altered in malignancy, 25‐27 MRS, or clinically MRSI, has the potential to be a sensitive biomarker of disease type, stage, and aggressiveness 25‐27 and has been reported to predict the efficacy of therapies including chemotherapy 25,27,28 and radiation 29‐31 . Challenges include the relatively low SNR of the MRS signal due to the significantly decreased amount of hydrogen in metabolites compared to water (~ 110 Molar vs ~1–10 milliMolar) and the need for a highly uniform B 0 field.…”

Section: Mr Biomarkers Associated Biologic and Genetic Processes And Imaging Techniquesmentioning

confidence: 99%

“…MRS-derived absolute or relative metabolite concentration can be considered a Type 1 biomarker given that MRS has been shown to identify malignancies in a range of organs and is predictive of therapeutic intervention. [25][26][27][28][29][30][31] Additionally, MRS-derived concentrations can be considered ratio variables, since zero theoretically indicates the absence of a given metabolite and a multiplicative increase or decrease in the value indicates a proportional increase or decrease in the concentration of the metabolite in question. As ratio variables, MRS-derived concentrations qualify as a QIB.…”

Section: A3 Spectroscopymentioning

confidence: 99%

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Magnetic resonance biomarkers in radiation oncology: The report of AAPM Task Group 294

et al. 2021

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A magnetic resonance (MR) biologic marker (biomarker) is a measurable quantitative characteristic that is an indicator of normal biological and pathogenetic processes or a response to therapeutic intervention derived from the MR imaging process. There is significant potential for MR biomarkers to facilitate personalized approaches to cancer care through more precise disease targeting by quantifying normal versus pathologic tissue function as well as toxicity to both radiation and chemotherapy. Both of which have the potential to increase the therapeutic ratio and provide earlier, more accurate monitoring of treatment response. The ongoing integration of MR into routine clinical radiation therapy (RT) planning and the development of MR guided radiation therapy systems is providing new opportunities for MR biomarkers to personalize and improve clinical outcomes. Their appropriate use, however, must be based on knowledge of the physical origin of the biomarker signal, the relationship to the underlying biological processes, and their strengths and limitations. The purpose of this report is to provide an educational resource describing MR biomarkers, the techniques 1 Med. Phys.

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Section: Mr Biomarkers Associated Biologic and Genetic Processes And Imaging Techniquesmentioning

confidence: 99%

Section: A3 Spectroscopymentioning

confidence: 99%

Magnetic resonance biomarkers in radiation oncology: The report of AAPM Task Group 294

et al. 2021

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“…Signals can also be quantified from glutamate, glutamine, myo-inositol, taurine, alanine, lactate, lipids, aspartate, and sometimes from glucose, glycine and citrate. Several publications provide detailed descriptions of the appearance, function and significance of these metabolites (Govindaraju et al 2000, Barker et al 2010, Howe and Peet 2016.…”

Section: Metabolitesmentioning

confidence: 99%

Clinical applications ofin vivomagnetic resonance spectroscopy in oncology

Payne

2018

Phys. Med. Biol.

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Brief introduction to magnetic resonance spectroscopyMagnetic resonance spectroscopy (MRS) can be used to probe tissue biochemistry in vivo by detecting signals from many metabolites, primarily those which have a low molecular weight and a concentration of a few mmol l −1 . MRS uses the same hardware as magnetic resonance imaging (MRI). Examples of 1 H MR spectra acquired from brain are shown in figure 1. A brief introduction is given here for the benefit of readers not familiar with the basic principles of MRS to provide a basic framework to understand the subsequent clinical applications. For more detail there are a number of good books describing in vivo MRS with helpful chapters on methods and applications (de Graaf 2007, Barker et al 2010.Some atoms (such as 1 H, 13 C, 31 P, 23 Na and 19 F) have nuclei with a magnetic dipole moment. The sum effect of all the magnetic dipoles is known as the bulk magnetisation. In a magnetic field and at thermal equilibrium the bulk magnetisation is aligned with the magnetic field. Application of an alternating magnetic field at the appropriate frequency (see equation (1) below) causes the bulk magnetisation to rotate away from the direction of the static magnetic field. The magnetisation then freely rotates about the static field at this same frequency. In time the bulk magnetisation relaxes back to thermal equilibrium parallel to the static field. If a detector coil is placed close to the sample a small current will be induced in it by the rotating magnetisation. This signal is known as the free induction decay (FID). The spectrum of frequency components (such as shown in figure 1) is obtained by Fourier transform of this signal.The frequency position of a resonance peak in Hz (often known as the Larmor precession frequency) is determined by the following equation:where γ is the gyromagnetic ratio of the nucleus (e.g. 2.675 × 10 8 rad/T/s for 1 H), and B local is the local field at the atomic nucleus. B local is determined primarily by the magnitude of the applied magnetic field (typically 1.5 T or 3 T for clinical MRI scanners), but it is slightly modified by the shielding effect of the electron cloud associated with bonding electrons (the chemical shift

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Characterizing Brain Tumors by MRS

Cited by 2 publications

References 113 publications

Magnetic resonance biomarkers in radiation oncology: The report of AAPM Task Group 294

Magnetic resonance biomarkers in radiation oncology: The report of AAPM Task Group 294

Clinical applications ofin vivomagnetic resonance spectroscopy in oncology

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