{"doi":"10.1002/mrm.30602","title":"<scp>B<sub>1</sub></scp>‐corrected breast <scp>T<sub>1</sub></scp> mapping at ultralow field","abstract":"Abstract Purpose This study aims to develop an efficient T 1 mapping approach that is free from systematic bias caused by B 1 inhomogeneity in ultralow‐field (ULF) MRI and to determine the T 1 values (without fat suppression) of breast tissues at 6.5 mT. Methods We describe here a method for ULF T 1 mapping using a variable flip angle approach for both mapping T 1 and B 1 . The B 1 mapping is used to correct the T 1 maps—and, unique to operation in the ULF regime, a B 1 map acquired in a phantom can be applied to the in vivo T 1 mapping data, reducing in vivo scan time. The T 1 mapping method was validated in vitro with copper sulphate phantoms at seven different concentrations. A breast phantom was scanned to test the T 1 mapping protocol. Four healthy volunteers were recruited for T 1 mapping to obtain in vivo T 1 values of breast tissues. No fat suppression was implemented in this preliminary study. Results The copper sulphate phantom T 1 map measurements have less than 13% deviation from the reference T 1 values, and less than 6% deviation when the reference T 1 was greater than 50 ms. Four healthy volunteers were scanned for T 1 mapping. In these in vivo breast T 1 maps, the 25th to 75th percentiles ranged from 79 to 243 ms at 6.5 mT. Conclusion Variable flip angle method can be used for both B 1 and T 1 mapping at ULFs, which enables efficient in vivo T 1 mapping for ULF MRI.","journal":"Magnetic Resonance in Medicine","year":2025,"id":541515,"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":0.9509,"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":773568,"name":"Néha Koonjoo","orcid":"0000-0003-0854-0047","position":1,"is_corresponding":false},{"id":513772,"name":"Stephen Ogier","orcid":"0000-0003-1098-1693","position":2,"is_corresponding":false},{"id":1368241,"name":"Thomas Boele","orcid":"0000-0001-9322-7762","position":3,"is_corresponding":false},{"id":1330999,"name":"Mansi A. Saksena","orcid":"0000-0002-8545-0785","position":4,"is_corresponding":false},{"id":583136,"name":"Kathryn E. Keenan","orcid":"0000-0001-9070-5255","position":5,"is_corresponding":false},{"id":241416,"name":"Matthew S. Rosen","orcid":"0000-0002-7194-002X","position":6,"is_corresponding":false},{"id":238339,"name":"Sheng Shen","orcid":"0000-0002-4320-2732","position":0,"is_corresponding":true}],"reference_count":54,"raw_metadata":null,"created_at":"2026-07-19T02:52:47.161928Z","pmid":"40523085","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":[]}