Spectroscopy:
            <sup>1</sup>
            H Metabolite Concentrations

Tofts, Paul S.; Waldman, Adam

doi:10.1002/0470869526.ch9

Cited by 10 publications

(10 citation statements)

References 93 publications

(148 reference statements)

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“…The most common procedures for calculating absolute concentrations 23,73 are (1) reference to the water signal as the internal standard, (2) use of a separately recorded reference signal from an external vial, and (3) signal calibration based on the principle of reciprocity. 74 All three methods can lead to large systematic errors and it is advisable to double check the results for consistency and plausibility.…”

Section: Sources Of Error In Procedures Of Absolute Quantitationmentioning

confidence: 99%

Issues of spectral quality in clinical ¹H‐magnetic resonance spectroscopy and a gallery of artifacts

2004

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In spite of the facts that magnetic resonance spectroscopy (MRS) is applied as clinical tool in non-specialized institutions and that semi-automatic acquisition and processing tools can be used to produce quantitative information from MRS exams without expert information, issues of spectral quality and quality assessment are neglected in the literature of MR spectroscopy. Even worse, there is no consensus among experts on concepts or detailed criteria of quality assessment for MR spectra. Furthermore, artifacts are not at all conspicuous in MRS and can easily be taken for true, interpretable features. This article aims to increase interest in issues of spectral quality and quality assessment, to start a larger debate on generally accepted criteria that spectra must fulfil to be clinically and scientifically acceptable, and to provide a sample gallery of artifacts, which can be used to raise awareness for potential pitfalls in MRS.

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Section: Sources Of Error In Procedures Of Absolute Quantitationmentioning

confidence: 99%

Issues of spectral quality in clinical ¹H‐magnetic resonance spectroscopy and a gallery of artifacts

2004

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“…Using the phantom replacement technique as described by Tofts and Waldman, metabolite concentrations for 2‐HG were calculated according to

[C i] = [C r] \frac{S_{i} V_{r} N_{r} c_{sans-serif-italicT sans-serif1r} c_{sans-serif-italicT sans-serif2r} T_{i} ρ_{i} c_{load}}{S_{r} V_{i} N_{i} c_{sans-serif-italicT sans-serif1i} c_{sans-serif-italicT sans-serif2i} T_{r} ρ_{r} c_{csf}}

…”

Section: Methodsmentioning

confidence: 99%

“…The Using the phantom replacement technique as described by Tofts and Waldman, metabolite concentrations for 2-HG were calculated according to 33 Ci…”

Section: Phantom Replacementmentioning

confidence: 99%

Fitting algorithms and baseline correction influence the results of non‐invasive in vivo quantitation of 2‐hydroxyglutarate with ¹H‐MRS

Wenger¹,

Hattingen

Harter

et al. 2018

NMR in Biomedicine

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1H‐MRS enables non‐invasive detection of 2‐hydroxyglutarate (2‐HG), an oncometabolite accumulating in gliomas carrying mutations in the isocitrate dehydrogenase (IDH) genes. Reliable 2‐HG quantitation requires reproducible post‐processing, deployment of fitting algorithms and quantitation methods. We prospectively enrolled 38 patients with suspected or recently diagnosed gliomas (IDH mutated n = 26). The MRI protocol included a 1H single voxel PRESS sequence with volumes of usually 8 mL or more (20 × 20 × 20 mm3) at TE = 97 ms and 180° pulse spacing. Our aim was to evaluate the reliability of 2‐HG quantitation comparing two frequently used software tools and their respective options of baseline correction (jMRUI with the time domain methods AQSES and QUEST, and LCModel, which analyzes the frequency domain data). For AQSES, degrees of freedom for baseline correction constrains were varied. For LCModel, baseline correction was obtained with and without correction of the unknown background term (predefined macromolecules, lipids). Tissue concentrations were calculated based on the phantom replacement method. Quantitation of 2‐HG levels showed similar mean 2‐HG tissue concentrations for IDH mutated tumors (2.65mM, range 3.06–2.20) for all methods. Bland–Altman plots (difference plots) did not reveal a systematic bias (fixed bias) for any of the algorithms tested, and we were able to show a significant correlation regarding 2‐HG concentration at the same echo time with few statistical outliers (parametric correlation). However, evaluation of outliers suggested that in vivo quantitation of 2‐HG is affected not only by the fitting domain (time or frequency), but also by the baseline correction, which is a major contributing factor to the result of 2‐HG fitting. Clinical application of 2‐HG quantitation as a prognostic or predictive biomarker, particularly in multicenter trials, requires standardized use of fitting methods and baseline correction procedures.

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“…Operators' manuals from major MR system manufacturers also provide concise information on the physics of MRS (Kohler, 1993;General Electric, 1999;Siemens, 2002Siemens, , 2004. Finally, the textbook by Tofts on quantitative MR of the brain (Tofts and Waldman, 2003) includes a concise yet thorough chapter covering key concepts, considerations, and procedures along with many valuable citations. Information from these cited sources has been used for the introductory parts of this review.…”

Section: Introductionmentioning

confidence: 99%

Magnetic resonance spectroscopy of the brain: a review of physical principles and technical methods

Buonocore¹,

Maddock²

2015

Reviews in the Neurosciences

102

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AbstractMagnetic resonance spectroscopy (MRS) provides unique information about the neurobiological substrates of brain function in health and disease. However, many of the physical principles underlying MRS are distinct from those underlying magnetic resonance imaging, and they may not be widely understood by neuroscientists new to this methodology. This review describes these physical principles and many of the technical methods in current use for MRS experiments. A better understanding these principles and methods may help investigators select pulse sequences and quantification methods best suited to the aims of their research program and avoid pitfalls that can hamper new investigators in this field.

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Spectroscopy: ¹ H Metabolite Concentrations

Cited by 10 publications

References 93 publications

Issues of spectral quality in clinical ¹H‐magnetic resonance spectroscopy and a gallery of artifacts

Issues of spectral quality in clinical ¹H‐magnetic resonance spectroscopy and a gallery of artifacts

Fitting algorithms and baseline correction influence the results of non‐invasive in vivo quantitation of 2‐hydroxyglutarate with ¹H‐MRS

Magnetic resonance spectroscopy of the brain: a review of physical principles and technical methods

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Spectroscopy: 1 H Metabolite Concentrations

Cited by 10 publications

References 93 publications

Issues of spectral quality in clinical 1H‐magnetic resonance spectroscopy and a gallery of artifacts

Issues of spectral quality in clinical 1H‐magnetic resonance spectroscopy and a gallery of artifacts

Fitting algorithms and baseline correction influence the results of non‐invasive in vivo quantitation of 2‐hydroxyglutarate with 1H‐MRS

Magnetic resonance spectroscopy of the brain: a review of physical principles and technical methods

Contact Info

Product

Resources

About

Spectroscopy: ¹ H Metabolite Concentrations

Issues of spectral quality in clinical ¹H‐magnetic resonance spectroscopy and a gallery of artifacts

Issues of spectral quality in clinical ¹H‐magnetic resonance spectroscopy and a gallery of artifacts

Fitting algorithms and baseline correction influence the results of non‐invasive in vivo quantitation of 2‐hydroxyglutarate with ¹H‐MRS