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@ARTICLE{Lutz:292291,
author = {M. Lutz and C. S. Aigner and S. Flassbeck and F. Krueger
and C. G. F. Gatefait and C. Kolbitsch and B. Silemek and F.
Seifert and T. Schaeffter and S. Schmitter$^*$},
title = {{B}1-{MRF}: {L}arge dynamic range {MRF}-based absolute {B}
1 + mapping in the human body at 7{T}.},
journal = {Magnetic resonance in medicine},
volume = {92},
number = {6},
issn = {1522-2594},
address = {New York, NY [u.a.]},
publisher = {Wiley-Liss},
reportid = {DKFZ-2024-01652},
pages = {2473-2490},
year = {2024},
note = {#LA:E020#/ 2024 Dec;92(6):2473-2490},
abstract = {This study aims to map the transmit magnetic field ( B 1 +
$$ {B}_1^{+} $$ ) in the human body at 7T using MR
fingerprinting (MRF), with a focus on achieving high
accuracy and precision across a large dynamic range,
particularly at low flip angles (FAs).A FLASH-based MRF
sequence (B1-MRF) with high B 1 + $$ {B}_1^{+} $$
sensitivity was developed. Phantom and in vivo abdominal
imaging were performed at 7T, and the results were compared
with established reference methods, including a slow but
precise preparation-based method (PEX), saturated TurboFLASH
(satTFL), actual flip angle imaging (AFI) and Bloch-Siegert
shift (BSS).The MRF signal curve was highly sensitive to B 1
+ $$ {B}_1^{+} $$ , while T1 sensitivity was comparatively
low. The phantom experiment showed good agreement of B 1 +
$$ {B}_1^{+} $$ to PEX for a T1 range of 204-1691 ms
evaluated at FAs from 0° to 70°. Compared to the
references, a dynamic range increase larger than a factor of
two was determined experimentally. In vivo liver scans
showed a strong correlation between B1-MRF, satTFL, and
RPE-AFI in a low body mass index (BMI) subject (18.1 kg/m2).
However, in larger BMI subjects (≥25.5 kg/m2),
inconsistencies were observed in low B 1 + $$ {B}_1^{+} $$
regions for satTFL and RPE-AFI, while B1-MRF still provided
consistent results in these regions.B1-MRF provides accurate
and precise B 1 + $$ {B}_1^{+} $$ maps over a wide range of
FAs, surpassing the capabilities of existing methods in the
FA range < 60°. Its enhanced sensitivity at low FAs is
advantageous for various applications requiring precise B 1
+ $$ {B}_1^{+} $$ estimates, potentially advancing the
frontiers of ultra-high field (UHF) body imaging at 7T and
beyond.},
keywords = {B 1 + $$ {B}_1^{+} $$ mapping (Other) / 7 Tesla (Other) /
MRF (Other) / body MRI (Other) / ultrahigh field MRI
(Other)},
cin = {E020},
ddc = {610},
cid = {I:(DE-He78)E020-20160331},
pnm = {315 - Bildgebung und Radioonkologie (POF4-315)},
pid = {G:(DE-HGF)POF4-315},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:39133639},
doi = {10.1002/mrm.30242},
url = {https://inrepo02.dkfz.de/record/292291},
}