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@ARTICLE{Orzada:169709,
author = {S. Orzada$^*$ and T. Fiedler$^*$ and H. H. Quick and M.
Ladd$^*$},
title = {{P}ost-processing algorithms for specific absorption rate
compression.},
journal = {Magnetic resonance in medicine},
volume = {86},
number = {5},
issn = {1522-2594},
address = {New York, NY [u.a.]},
publisher = {Wiley-Liss},
reportid = {DKFZ-2021-01516},
pages = {2853-2861},
year = {2021},
note = {#EA:E020#LA:E020# / Volume86, Issue5 November 2021 Pages
2853-2861},
abstract = {Compression of local specific absorption rate (SAR)
matrices is essential for enabling SAR monitoring and
efficient pulse calculation in parallel transmission.
Improvements in compression result in lower error margin
and/or lower number of virtual observation points (VOPs).
The purpose of this work is to introduce two algorithms for
post-processing of already compressed VOP sets. One
calculates individual overestimation matrices for the VOPs
to reduce overestimation, the other identifies redundant
VOPs.The first algorithm was evaluated for VOP sets
calculated for three different transmit arrays with either 8
or 16 channels. For each array, two different overestimation
matrices were used to generate the VOP sets. Each
post-processed VOP set was evaluated using one million
random excitation vectors and the results compared to the
VOP set before post-processing. The second algorithm was
evaluated by utilizing the same random excitation vectors
and comparing the results after removal of the redundant
VOPs with the results before removal to verify that these
were identical.The first algorithm reduced the mean
overestimation by up to four fifths compared to the original
set, while keeping the number of VOPs constant. The second
algorithm decreased the number of VOPs generated by a
compression with Eichfelder and Gebhardt's algorithm by more
than $40\%$ in $40\%$ of the investigated cases and by more
than $20\%$ in $73\%$ of the investigated cases.Two
post-processing algorithms are presented that enhance
previously compressed VOP sets by improving the accuracy per
number of VOPs.},
keywords = {MRI (Other) / SAR (Other) / VOP compression (Other) / VOPs
(Other) / local SAR (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:34216047},
doi = {10.1002/mrm.28909},
url = {https://inrepo02.dkfz.de/record/169709},
}