Uncertainties of calculated Cramér-Rao lower bounds: implications for quantitative MRS.
Magn Reson Med
; 81(2): 759-764, 2019 02.
Article
em En
| MEDLINE
| ID: mdl-30203860
ABSTRACT
PURPOSE:
To investigate the uncertainties on relative Cramér-Rao lower bound (rCRB) estimates and demonstrate their biasing effects in MRS quantification. THEORY ANDMETHODS:
Simulations were performed to calculate the distribution of the computed rCRB (noted rCRB*) for several rCRB levels. One hundred thousand simulations per rCRB value were performed on simulated NMR signals containing either 1 signal (singlet) or 2 partially overlapping signals. False-positive and false-negative risks were compiled for different threshold levels. rCRB* distribution was experimentally checked on a deuterated water sample using a 9.4 Tesla vertical magnet.RESULTS:
Simulations showed that (1) rCRB* distribution is asymmetrical, with a right-tailed distribution increasing the risk of accepting false-positive data (i.e., accepting an rCRB* value whereas the true rCRB value is higher than the threshold level) and (2) distribution broadness increases with increasing rCRB level. Simulations with overlapped peaks lead to more inaccuracy in the rCRB estimation. Probabilities of false detection increase with increasing threshold level.CONCLUSION:
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.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Simulação por Computador
/
Processamento de Imagem Assistida por Computador
/
Espectroscopia de Ressonância Magnética
/
Incerteza
Tipo de estudo:
Health_economic_evaluation
/
Prognostic_studies
/
Risk_factors_studies
Limite:
Humans
Idioma:
En
Revista:
Magn Reson Med
Assunto da revista:
DIAGNOSTICO POR IMAGEM
Ano de publicação:
2019
Tipo de documento:
Article
País de afiliação:
França