Uncertainties of calculated Cramér‐Rao lower bounds: implications for quantitative MRS

Bonny, Jean‐Marie; Pagès, Guilhem

doi:10.1002/mrm.27415

Cited by 2 publications

(1 citation statement)

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“…The evaluation of EFU versus actual variance found in the evaluation of spectra with equal noise indicated that some of the EFUs overestimate the actual fit error, in particular for LCModel with limited SNR, even though the CRLB should be a lower limit of the fit error 30 . Of course, it has to be kept in mind that the indicated fit errors are just estimates 31 of the true fit error and may well deviate substantially; however, to find such large overestimation for multiple cases hints at a systematic bias.…”

Section: Discussionmentioning

confidence: 99%

Results and interpretation of a fitting challenge for MR spectroscopy set up by the MRS study group of ISMRM

Marjańska

Deelchand

Kreis

2021

Magnetic Resonance in Med

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Fitting of MRS data plays an important role in the quantification of metabolite concentrations. Many different spectral fitting packages are used by the MRS community. A fitting challenge was set up to allow comparison of fitting methods on the basis of performance and robustness. Methods: Synthetic data were generated for 28 datasets. Short-echo time PRESS spectra were simulated using ideal pulses for the common metabolites at mostly near-normal brain concentrations. Macromolecular contributions were also included.Modulations of signal-to-noise ratio (SNR); lineshape type and width; concentrations of γ-aminobutyric acid, glutathione, and macromolecules; and inclusion of artifacts and lipid signals to mimic tumor spectra were included as challenges to be coped with. Results: Twenty-six submissions were evaluated. Visually, most fit packages performed well with mostly noise-like residuals. However, striking differences in fit performance were found with bias problems also evident for well-known packages.In addition, often error bounds were not appropriately estimated and deduced confidence limits misleading. Soft constraints as used in LCModel were found to substantially influence the fitting results and their dependence on SNR. Conclusions: Substantial differences were found for accuracy and precision of fit results obtained by the multiple fit packages.

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Section: Discussionmentioning

confidence: 99%

Results and interpretation of a fitting challenge for MR spectroscopy set up by the MRS study group of ISMRM

Marjańska

Deelchand

Kreis

2021

Magnetic Resonance in Med

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Assessing the Feasibility of Dynamic ³¹P Spectroscopy for Metabolic Studies With a 1.0T Extremity Scanner

Carrell¹,

Gu²,

Bosshard³

et al. 2022

IEEE Trans. Biomed. Eng.

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Uncertainties of calculated Cramér‐Rao lower bounds: implications for quantitative MRS

Abstract: Analyzing results thanks to a CRB (or rCRB) based on experimental measurements might lead to misinterpretations. To exploit the rCRB* as rejection criteria, a conservative threshold level of 20% is recommended in order to limit the probability of false alarms.

Cited by 2 publications

References 25 publications

Results and interpretation of a fitting challenge for MR spectroscopy set up by the MRS study group of ISMRM

Results and interpretation of a fitting challenge for MR spectroscopy set up by the MRS study group of ISMRM

Assessing the Feasibility of Dynamic ³¹P Spectroscopy for Metabolic Studies With a 1.0T Extremity Scanner

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Uncertainties of calculated Cramér‐Rao lower bounds: implications for quantitative MRS

Abstract: Analyzing results thanks to a CRB (or rCRB) based on experimental measurements might lead to misinterpretations. To exploit the rCRB* as rejection criteria, a conservative threshold level of 20% is recommended in order to limit the probability of false alarms.

Cited by 2 publications

References 25 publications

Results and interpretation of a fitting challenge for MR spectroscopy set up by the MRS study group of ISMRM

Results and interpretation of a fitting challenge for MR spectroscopy set up by the MRS study group of ISMRM

Assessing the Feasibility of Dynamic 31P Spectroscopy for Metabolic Studies With a 1.0T Extremity Scanner

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Assessing the Feasibility of Dynamic ³¹P Spectroscopy for Metabolic Studies With a 1.0T Extremity Scanner