Global optimization of default phases for parallel transmit coils for ultra-high-field cardiac MRI.
PLoS One
; 16(8): e0255341, 2021.
Article
de En
| MEDLINE
| ID: mdl-34358243
ABSTRACT
The development of novel multiple-element transmit-receive arrays is an essential factor for improving B1+ field homogeneity in cardiac MRI at ultra-high magnetic field strength (B0 > = 7.0T). One of the key steps in the design and fine-tuning of such arrays during the development process is finding the default driving phases for individual coil elements providing the best possible homogeneity of the combined B1+-field that is achievable without (or before) subject-specific B1+-adjustment in the scanner. This task is often solved by time-consuming (brute-force) or by limited efficiency optimization methods. In this work, we propose a robust technique to find phase vectors providing optimization of the B1-homogeneity in the default setup of multiple-element transceiver arrays. The key point of the described method is the pre-selection of starting vectors for the iterative solver-based search to maximize the probability of finding a global extremum for a cost function optimizing the homogeneity of a shaped B1+-field. This strategy allows for (i) drastic reduction of the computation time in comparison to a brute-force method and (ii) finding phase vectors providing a combined B1+-field with homogeneity characteristics superior to the one provided by the random-multi-start optimization approach. The method was efficiently used for optimizing the default phase settings in the in-house-built 8Tx/16Rx arrays designed for cMRI in pigs at 7T.
Texte intégral:
1
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
IRM dynamique
/
Coeur
Type d'étude:
Prognostic_studies
Limites:
Animals
Langue:
En
Journal:
PLoS One
Sujet du journal:
CIENCIA
/
MEDICINA
Année:
2021
Type de document:
Article
Pays d'affiliation:
Allemagne