Evidence map›Paper›PMID 39301784›Full record

ArticleMagnetic resonance in medicine2025

Local and whole-body SAR in UHF body imaging: Implications for SAR matrix compression.

Thomas M Fiedler, Mark E Ladd, Stephan Orzada

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Article in Magnetic resonance in medicine, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 5 papers.

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5citing papers in PubMed
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1 · What the graph read from it

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3 · Its place in the literature

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5 citing papers in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

3 authors.

Thomas M FiedlerMedical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.ORCID 0000-0002-1556-375X
Mark E LaddMedical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Stephan OrzadaMedical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.ORCID 0000-0001-9784-4354

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

purposeTransmit 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.

methodsSimulations 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.

resultsThe 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).

conclusionFor 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.

Indexed as

Data CompressionMagnetic Resonance ImagingWhole Body ImagingComputer SimulationEquipment DesignHumansImage EnhancementPhantoms, ImagingReproducibility of ResultsSensitivity and Specificitylocal SARUHF body imagingVOPswhole‐body SAR

Identifiers

PMID39301784
PMCPMC11604848

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