{"doi":"10.1002/mrm.29615","title":"Quantification of cross‐relaxation in downfield <scp><sup>1</sup>H MRS</scp> at 7 T in human calf muscle","abstract":"Purpose The purpose of this study was to characterize the 1 H downfield MR spectrum from 8.0 to 10.0 ppm of human skeletal muscle at 7 T and determine the T 1 and cross‐relaxation rates of observed resonances. Methods We performed downfield MRS in the calf muscle of 7 healthy volunteers. Single‐voxel downfield MRS was collected using alternately selective or broadband inversion‐recovery sequences and spectrally selective 90° E‐BURP RF pulse excitation centered at 9.0 ppm with bandwidth = 600 Hz (2.0 ppm). MRS was collected using TIs of 50–2500 ms. We modeled recovery of the longitudinal magnetization of three observable resonances using two models: (1) a three‐parameter model accounting for the apparent T 1 recovery and (2) a Solomon model explicitly including cross‐relaxation effects. Results Three resonances were observed in human calf muscle at 7 T at 8.0, 8.2, and 8.5 ppm. We found broadband (broad) and selective (sel) inversion recovery T 1 = mean ± SD (ms): T 1‐broad,8.0ppm = 2108.2 ± 664.5, T 1‐sel,8.0ppm = 753.6 ± 141.0 ( p = 0.003); T 1‐broad,8.2ppm = 2033.5 ± 338.4, T 1‐sel,8.2ppm = 135.3 ± 35.3 ( p &lt; 0.0001); and T 1‐broad,8.5ppm = 1395.4 ± 75.4, T 1‐sel,8.5ppm = 107.1 ± 40.0 ( p &lt; 0.0001). Using the Solomon model, we found T 1 = mean ± SD (ms): T 1‐8.0ppm = 1595.6 ± 491.1, T 1‐8.2ppm = 1737.2 ± 963.7, and T 1‐8.5ppm = 849.8 ± 282.0 ( p = 0.04). Post hoc tests corrected for multiple comparisons showed no significant difference in T 1 between peaks. The cross‐relaxation rate σ AB = mean ± SD (Hz) of each peak was σ AB,8.0ppm = 0.76 ± 0.20, σ AB,8.2ppm = 5.31 ± 2.27, and σ AB,8.5ppm = 7.90 ± 2.74 ( p &lt; 0.0001); post hoc t‐tests revealed the cross‐relaxation rate of the 8.0 ppm peak was significantly slower than the peaks at 8.2 ppm ( p = 0.0018) and 8.5 ppm ( p = 0.0005). Conclusion We found significant differences in effective T 1 and cross‐relaxation rates of 1 H resonances between 8.0 and 8.5 ppm in the healthy human calf muscle at 7 T.","journal":"Magnetic Resonance in Medicine","year":2023,"id":372241,"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":5,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.729,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2023-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":275710,"name":"Mark A. Elliott","orcid":"0000-0003-4191-5509","position":1,"is_corresponding":false},{"id":469610,"name":"Ravi Prakash Reddy Nanga","orcid":"0000-0002-3644-5656","position":2,"is_corresponding":false},{"id":891953,"name":"Neil Wilson","orcid":"0009-0002-7766-2929","position":3,"is_corresponding":false},{"id":469609,"name":"Abigail Cember","orcid":"0000-0002-4747-6079","position":4,"is_corresponding":false},{"id":227867,"name":"Ravinder Reddy","orcid":"0000-0003-4580-2392","position":5,"is_corresponding":false},{"id":329911,"name":"Walter R. Witschey","orcid":"0000-0003-1669-2120","position":6,"is_corresponding":false},{"id":686831,"name":"Sophia Swago","orcid":"0000-0001-8334-4746","position":0,"is_corresponding":true}],"reference_count":31,"raw_metadata":null,"created_at":"2026-07-19T01:15:54.000926Z","pmid":"36807934","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":[]}