{"doi":"10.1002/jmri.29542","title":"Editorial for “Self‐Gated Radial Free‐Breathing Liver <scp>MR</scp> Elastography: Assessment of Technical Performance in Children at <scp>3T</scp>”","abstract":"Magnetic resonance elastography (MRE) is regarded as the most accurate noninvasive method for detecting and staging liver fibrosis, based on extensive published evidence.1 Limitations in the diagnostic performance of liver biopsy in this role, due to subjective interpretation and sampling effects, are increasingly being recognized.2 MRE is now widely available and deployed on more than 2500 MRI systems globally. In the United States, the established role of MRE has been recognized by the American Medical Association through assignment of a Category I Current Procedural Terminology (CPT) code (#76391). Because MRE can be performed in less than a minute of imaging time, it has been assigned a relatively modest cost by private and governmental insurance payors.3 A consensus protocol for liver MRE has been developed and published by the Quantitative Imaging Biomarkers Alliance (QIBA) and describes best practices in performing and analyzing exams to obtain the most reliable results.4 With regulatory-approved implementations available from most MRI manufacturers, MRE data are typically acquired in 1 to 4 periods of suspended respiration, each lasting about 15 seconds. If breath-holding is not adequate during the MRE acquisition, the resulting images may be badly degraded by motion artifact. While breath-holding on request is readily accomplished by most adult patients, it can be difficult or impossible in younger pediatric patients. Availability of an MRE technique that could be performed during free breathing would therefore help to make MRE more available as alternative to liver biopsy in pediatric patients. In this issue of JMRI, Kalafi et al describe development and testing of a method for performing MRE exams during free breathing.5 The technique employs a radial k-space trajectory and several acceleration techniques to acquire MRE data in four slices within a 4-minute free breathing acquisition. An advantage of the radial acquisition method is that every TR provides a data point at the center of k-space, that varies in amplitude systematically during the respiratory cycle. This signal can be used to “self-gate” the acquired data, rejecting measurements that are not in a specified range within the respiratory cycle, thereby reducing motion artifacts in the reconstructed images.6 The authors compared the performance of their accelerated, self-gated, free breathing technique to results obtained with a conventional MRE technique using cartesian acquisition, requiring four breath-holds. The study evaluated technical quality, measurement repeatability, and agreement of the free breathing MRE measurements with the breath-hold measurements in a series of 26 pediatric subjects. The results showed that with a 60% gating acceptance window, the free breathing technique provided liver stiffness measurements “with close agreement and comparable repeatability” to the conventional beath-hold technique. The authors of this well-designed study conclude with good justification that the proposed radial free breathing, self-gated MRE technique is a “promising tool” for obtaining reliable liver stiffness measurements in pediatric practice when reliable breath-holding may not be possible. There are, of course, other options for implementing respiratory gating in MRE, such as using a belt sensor or a navigator echo for prospective gating with conventional cartesian acquisition.7, 8 A respiratory signal obtained this way can also be used for retrospective gating with conventional cartesian acquisition, if sufficient data are acquired. The liver is a large organ and since the goal of MRE is usually to obtain a global stiffness measurement, simple averaging of MRE data without gating over many respiratory cycles may also be a good option.8-10 Given the feasibility of several different approaches for free breathing MRE, it is likely that future work will compare these options to find the most robust method. The work by Kalafi et al, is a good blueprint f","journal":"Journal of Magnetic Resonance Imaging","year":2024,"id":501395,"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":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9608,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2024-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":275036,"name":"Richard L. Ehman","orcid":"0000-0001-7041-5074","position":0,"is_corresponding":true}],"reference_count":10,"raw_metadata":null,"created_at":"2026-07-19T02:10:15.999370Z","pmid":"39052251","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":[]}