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Accuracy and precision of electrical permittivity mapping at 3T: the impact of three [Formula: see text] mapping techniques

PURPOSE: To investigate the sequence‐specific impact of [Formula: see text] amplitude mapping on the accuracy and precision of permittivity reconstruction at 3T in the pelvic region. METHODS: [Formula: see text] maps obtained with actual flip angle imaging (AFI), Bloch–Siegert (BS), and dual refocus...

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Detalles Bibliográficos
Autores principales: Gavazzi, Soraya, van den Berg, Cornelis A.T., Sbrizzi, Alessandro, Kok, H. Petra, Stalpers, Lukas J. A., Lagendijk, Jan J.W., Crezee, Hans, van Lier, Astrid L. H. M. W.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6593818/
https://www.ncbi.nlm.nih.gov/pubmed/30737816
http://dx.doi.org/10.1002/mrm.27675
Descripción
Sumario:PURPOSE: To investigate the sequence‐specific impact of [Formula: see text] amplitude mapping on the accuracy and precision of permittivity reconstruction at 3T in the pelvic region. METHODS: [Formula: see text] maps obtained with actual flip angle imaging (AFI), Bloch–Siegert (BS), and dual refocusing echo acquisition mode (DREAM) sequences, set to a clinically feasible scan time of 5 minutes, were compared in terms of accuracy and precision with electromagnetic and Bloch simulations and MR measurements. Permittivity maps were reconstructed based on these [Formula: see text] maps with Helmholtz‐based electrical properties tomography. Accuracy and precision in permittivity were assessed. A 2‐compartment phantom with properties and size similar to the human pelvis was used for both simulations and measurements. Measurements were also performed on a female volunteer’s pelvis. RESULTS: Accuracy was evaluated with noiseless simulations on the phantom. The maximum [Formula: see text] bias relative to the true [Formula: see text] distribution was 1% for AFI and BS and 6% to 15% for DREAM. This caused an average permittivity bias relative to the true permittivity of 7% to 20% for AFI and BS and 12% to 35% for DREAM. Precision was assessed in MR experiments. The lowest standard deviation in permittivity, found in the phantom for BS, measured 22.4 relative units and corresponded to a standard deviation in [Formula: see text] of 0.2% of the [Formula: see text] average value. As regards [Formula: see text] precision, in vivo and phantom measurements were comparable. CONCLUSIONS: Our simulation framework quantitatively predicts the different impact of [Formula: see text] mapping techniques on permittivity reconstruction and shows high sensitivity of permittivity reconstructions to sequence‐specific bias and noise perturbation in the [Formula: see text] map. These findings are supported by the experimental results.