Dataset Information

Accuracy and precision of electrical permittivity mapping at 3T: the impact of three B1+ mapping techniques.

ABSTRACT:

Purpose

To investigate the sequence-specific impact of B1+ amplitude mapping on the accuracy and precision of permittivity reconstruction at 3T in the pelvic region.

Methods

B1+ 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 B1+ 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 B1+ bias relative to the true B1+ 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 B1+ of 0.2% of the B1+ average value. As regards B1+ precision, in vivo and phantom measurements were comparable.

Conclusions

Our simulation framework quantitatively predicts the different impact of B1+ mapping techniques on permittivity reconstruction and shows high sensitivity of permittivity reconstructions to sequence-specific bias and noise perturbation in the B1+ map. These findings are supported by the experimental results.

SUBMITTER: Gavazzi S

PROVIDER: S-EPMC6593818 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

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Publications

Accuracy and precision of electrical permittivity mapping at 3T: the impact of three B1+ mapping techniques.

Gavazzi Soraya S van den Berg Cornelis A T CAT Sbrizzi Alessandro A Kok H Petra HP Stalpers Lukas J A LJA Lagendijk Jan J W JJW Crezee Hans H van Lier Astrid L H M W ALHMW

Magnetic resonance in medicine 20190208 6

<h4>Purpose</h4>To investigate the sequence-specific impact of B1+ amplitude mapping on the accuracy and precision of permittivity reconstruction at 3T in the pelvic region.<h4>Methods</h4>B1+ 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. Permitti ...[more]

PMID: 30737816

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Dataset Information

Accuracy and precision of electrical permittivity mapping at 3T: the impact of three B1+ mapping techniques.

Purpose

Methods

Results

Conclusions

Publications

Accuracy and precision of electrical permittivity mapping at 3T: the impact of three B1+ mapping techniques.

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