{"doi":"10.1002/jmri.70057","title":"<scp>MR</scp> Electrical Properties Tomography Acquisitions: A Guideline From the <scp>ISMRM</scp> Electro‐Magnetic Tissue Properties Study Group","abstract":"The electrical properties of human tissue (i.e., electrical conductivity σ and permittivity ε) can be measured quantitatively in vivo with standard MR sequences and standard MR systems using a technique called Electrical Properties Tomography (EPT) [1, 2]. The full implementation of EPT involves first measuring the complex RF transmit field component B1+ (i.e., its magnitude |B1+| and phase ϕ+) as modulated by the tissue electrical properties, and then reconstructing σ and ε from the modulated B1+. The reconstructed electrical properties correspond to the Larmor frequency of the applied main field strength B0. This article is meant as a short guideline for measuring complex B1+ for EPT. A comprehensive review on how to perform the subsequent reconstruction of σ and ε from the measured complex B1+ was reported earlier [3]. Software packages performing such reconstructions are available publicly [4-6], and so are EPT example datasets [7, 8]. This guideline will be complemented by two further EPT-related guidelines, that is on standardization and phantom building, provided in separate articles. Together, these three guidelines are thought to parallel corresponding guidelines on mapping magnetic properties of tissue [9]. Although sequences with simultaneous measurements of |B1+| and ϕ+ are possible [10], current practice is to use separate measurements for |B1+| and ϕ+, as described in the following. Numerous B1-mapping techniques for measuring |B1+| have been published, independent of EPT (e.g., Actual Flip angle Imaging (AFI) [11], Bloch-Siegert mapping [12], and Dual Refocusing Echo Acquisition Mode (DREAM) [13]). A comparison of B1-mapping techniques on the determination of ε primarily highlighted the need for high SNR [14]. On the other hand, reviews of B1-mapping techniques without reference to EPT were published [15]. Although relative units of |B1+| are sufficient for the majority of EPT approaches, such as differential equation-based methods, absolute scaling of |B1+| (e.g., in μT) is required for other EPT approaches, like some integral equation-based methods, as these rely on accurate field magnitudes to compute the necessary integrals. A standard MR system does not allow ϕ+ to be measured. Consequently, most EPT studies make use of the so-called transceive phase ϕ±, which is the superposition of the B1-phases from RF transmission and RF reception, assuming ϕ+~ϕ±/2 (so-called “Transceive Phase Assumption”, TPA). Thus, this subsection describes the measurement of ϕ±. In principle, the phase image of any clinical sequence can be taken as ϕ±; however, it must be free of components unrelated to RF penetration. Unwanted phase contributions originate mainly from three sources: (A) B0-inhomogeneities, (B) gradient-induced eddy currents, (C) patient/tissue motion. (A) Phase due to B0-inhomogeneities can be avoided by using spin-echo-based sequences, gradient-echo-based sequences with balanced gradients, or sequences with ultrashort/zero TE [16]. Gradient-echo-based sequences without gradient balancing can be used to estimate ϕ± if multiple echoes with different TEs are acquired and the observed phase for each voxel is extrapolated back to TE = 0 [17]. In the presence of chemical shift effects (e.g., due to fat), one might not be able to resolve the additional phase component. (B) Unwanted phase due to eddy currents typically appears as artificially increased conductivity along one side of the field-of-view (FOV) and artificially decreased conductivity along the other side of the FOV. This too can be eliminated by using gradient-echo-based sequences with balanced gradients or by repeating spin-echo sequences with inverted gradient polarization and averaging the results [18]. (C) As motion affects all types of sequences, standard motion correction schemes should be applied to minimize motion-induced phase contributions. Due to the applied numerical derivatives, reconstructed maps are typically more corrupted by motion than the or","journal":"Journal of Magnetic Resonance Imaging","year":2025,"id":528691,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":2,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9545,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1406997,"name":"Cornelis A. T. van den Berg","orcid":"0000-0002-5565-6889","position":1,"is_corresponding":false},{"id":580449,"name":"Ilias I. Giannakopoulos","orcid":"0000-0003-2180-5898","position":2,"is_corresponding":false},{"id":1406998,"name":"Zhongzheng He","orcid":"0009-0001-9680-7671","position":3,"is_corresponding":false},{"id":1406999,"name":"Y.Z. Ider","orcid":"0000-0002-1961-6804","position":4,"is_corresponding":false},{"id":1407000,"name":"Kyu‐Jin Jung","orcid":"0000-0003-2842-1707","position":5,"is_corresponding":false},{"id":1407001,"name":"Nitish Katoch","orcid":"0000-0003-4488-201X","position":6,"is_corresponding":false},{"id":1407002,"name":"Dong‐Hyun Kim","orcid":"0000-0002-6717-7770","position":7,"is_corresponding":false},{"id":439963,"name":"Riccardo Lattanzi","orcid":"0000-0002-8240-5903","position":8,"is_corresponding":false},{"id":1407003,"name":"Paul Soullié","orcid":"0000-0002-1294-4338","position":9,"is_corresponding":false},{"id":1407004,"name":"Ulrich Katscher","orcid":"0000-0003-1379-1115","position":10,"is_corresponding":false},{"id":1406996,"name":"Stefano Mandija","orcid":"0000-0002-4612-5509","position":0,"is_corresponding":true}],"reference_count":22,"raw_metadata":null,"created_at":"2026-07-19T02:50:52.565868Z","pmid":"40831340","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}