Journal Article

DKFZ-2024-01898

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Local and whole-body SAR in UHF body imaging: Implications for SAR matrix compression.

Fiedler, T. (First author)DKFZ* ; Ladd, M. E.DKFZ* ; Orzada, S. (Last author)DKFZ*

2025
Wiley-Liss New York, NY [u.a.]

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Please use a persistent id in citations: doi:10.1002/mrm.30306

Abstract: Transmit arrays for body imaging have characteristics of both volume and local transmit coils. This study evaluates two specific absorption rate (SAR) aspects, local and whole-body SAR, of arrays for body imaging at 7 T and also for a 3 T birdcage.Simulations were performed for six antenna arrays at 7 T and one 3 T birdcage. Local SAR matrices and the whole-body SAR matrix were computed and evaluated with random shims. A set of reduced local SAR matrices was determined by removing all matrices dominated by the whole-body SAR matrix.The results indicate that all RF transmit coils for body imaging in this study are constrained by the local SAR limit. The ratio between local and whole-body SAR is nevertheless smaller for arrays with large FOV, as these arrays also expose a larger part of the human body. By using the whole-body SAR matrix, the number of local SAR matrices can be reduced (e.g., 33.3% matrices remained for an 8-channel local array and 89.7% for a 30-channel remote array; 12.1% for the 3 T birdcage).For transmit antenna arrays used for body imaging at 7 T as well as for the 3 T birdcage, all evaluated cases show that the local SAR limit was reached before reaching the whole-body SAR limit. Nevertheless, the whole-body SAR matrix can be used to reduce the number of local SAR matrices, which is important to reduce memory and computing time for a virtual observation points (VOP) compression. This step can be included as a pre-compression prior to a VOP compression.

Keyword(s): UHF body imaging ; VOPs ; local SAR ; whole‐body SAR

Note: #EA:E020#LA:E020# / 2025 Feb;93(2):842-849

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Contributing Institute(s):

1. E020 Med. Physik in der Radiologie (E020)

Research Program(s):

1. 315 - Bildgebung und Radioonkologie (POF4-315) (POF4-315)

Appears in the scientific report 2024

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Database coverage:
; BIOSIS Previews ; Biological Abstracts ; Clarivate Analytics Master Journal List ; Current Contents - Clinical Medicine ; Current Contents - Life Sciences ; DEAL Wiley ; Essential Science Indicators ; IF < 5 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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