TY - JOUR
T1 - Improving B 1 + parametric estimation in the brain from multispin-echo sequences using a fusion bootstrap moves solver
AU - Calisto De Freitas, Andreia
AU - Gaspar, Andreia
AU - Sousa, Inês
AU - A. G. Teixeira, Rui Pedro
AU - Hajnal, Jo
AU - Nunes, Rita G.
N1 - Funding Information:
The authors acknowledge the following funding sources: Portuguese Foundation for Science and Technology (FCT—IF/00364/2013, UID/EEA/50009/2019, SFRH/BD/120006/2016, PTDC/EMD‐EMD/29686/2017, UIDB/50009/2020), and POR Lisboa 2020 (LISBOA‐01‐0145‐FEDER‐029686).
Publisher Copyright:
© 2021 International Society for Magnetic Resonance in Medicine
PY - 2021/11
Y1 - 2021/11
N2 - Purpose: To simultaneously estimate the (Formula presented.) field (along with the T
2) in the brain with multispin-echo (MSE) sequences and dictionary matching. Methods: T
2 mapping provides clinically relevant information such as in the assessment of brain degenerative diseases. It is commonly obtained with MSE sequences, and accuracy can be further improved by matching the MSE signal to a precomputed dictionary of echo-modulation curves. For additional T
1 quantification, transmit (Formula presented.) field knowledge is also required. Preliminary work has shown that although simultaneous brain (Formula presented.) estimation along with T
2 is possible, it presents a bimodal distribution with the main peak coinciding with the true value. By taking advantage of this, the (Formula presented.) maps are expected to be spatially smooth by applying an iterative method that takes into account each pixel neighborhood known as the fusion bootstrap moves solver (FBMS). The effect of the FBMS on (Formula presented.) accuracy and piecewise smoothness is investigated and different spatial regularization levels are compared. Total variation regularization was used for both (Formula presented.) and T
2 simultaneous estimation because of its simplicity as an initial proof-of-concept; future work could explore non edge-preserving regularization independently for (Formula presented.). Results: Improvements in (Formula presented.) accuracy (up to 45.37% and 16.81% (Formula presented.) error decrease) and recovery of spatially homogeneous maps are shown in simulations and in vivo 3.0T brain data, respectively. Conclusion: Accurate (Formula presented.) estimated values can be obtained from widely available MSE sequences while jointly estimating T
2 maps with the use of echo-modulation curve matching and FBMS at no further cost.
AB - Purpose: To simultaneously estimate the (Formula presented.) field (along with the T
2) in the brain with multispin-echo (MSE) sequences and dictionary matching. Methods: T
2 mapping provides clinically relevant information such as in the assessment of brain degenerative diseases. It is commonly obtained with MSE sequences, and accuracy can be further improved by matching the MSE signal to a precomputed dictionary of echo-modulation curves. For additional T
1 quantification, transmit (Formula presented.) field knowledge is also required. Preliminary work has shown that although simultaneous brain (Formula presented.) estimation along with T
2 is possible, it presents a bimodal distribution with the main peak coinciding with the true value. By taking advantage of this, the (Formula presented.) maps are expected to be spatially smooth by applying an iterative method that takes into account each pixel neighborhood known as the fusion bootstrap moves solver (FBMS). The effect of the FBMS on (Formula presented.) accuracy and piecewise smoothness is investigated and different spatial regularization levels are compared. Total variation regularization was used for both (Formula presented.) and T
2 simultaneous estimation because of its simplicity as an initial proof-of-concept; future work could explore non edge-preserving regularization independently for (Formula presented.). Results: Improvements in (Formula presented.) accuracy (up to 45.37% and 16.81% (Formula presented.) error decrease) and recovery of spatially homogeneous maps are shown in simulations and in vivo 3.0T brain data, respectively. Conclusion: Accurate (Formula presented.) estimated values can be obtained from widely available MSE sequences while jointly estimating T
2 maps with the use of echo-modulation curve matching and FBMS at no further cost.
KW - B1+ mapping
KW - multi spin-echo
KW - echo-modulation curves
UR - http://www.scopus.com/inward/record.url?scp=85109126047&partnerID=8YFLogxK
U2 - https://doi. org/10.1002/mrm.28878
DO - https://doi. org/10.1002/mrm.28878
M3 - Article
SN - 0740-3194
VL - 86
SP - 2426
EP - 2440
JO - Magnetic resonance in medicine
JF - Magnetic resonance in medicine
IS - 5
ER -
