{"doi":"10.1101/2022.09.16.508261","title":"On the origin of <i>R</i> <sub>2</sub> orientation dependence angle offsets in white matter","abstract":"ABSTRACT Purpose to identify the origin of confounding angle offset ε 0 in R 2 orientation dependence and to propose a novel framework for better characterizing anisotropic R 2 in brain white matter (WM). Methods Anisotropic ( ε ) rather than principal diffusivity direction (Φ) was theorized along axon fiber, with ε determined by all eigenvalues and eigenvectors from diffusion tensor. An extra parameter ε 0 was introduced into generalized magic angle effect function to account for any offset in R 2 orientation dependence derived from T 2 -weighted image ( b= 0). These dependences referenced by ε were compared to those referenced as usual by Φ at b -values of 1000 and 2000 (s/mm 2 ) on both linear and planar tensor image voxels in WM, based on public domain ultrahigh-resolution (760 µ m 3 ) Connectome DTI datasets of a healthy young adult brain. A Student’s t-test was used to assess the mean differences and the statistical significance was considered at P &lt; 0.05. Results Fitted ε 0 became zero if referenced by ε or nonzero if referenced by Φ, signifying the origin of ε 0 . Nonzero ε 0 relied on b -values and tensor shapes so did other model parameters, e.g., the amplitude of anisotropic R 2 (1/s) significantly increased when using a higher b -value for the linear tensor image voxels, i.e., 3.3±0.1 vs. 1.8±0.1, P &lt; 0.01. Conclusion The origin of R 2 orientation dependence angle offsets has been identified and the combined anisotropic diffusion and transverse relaxation models have fully quantified R 2 orientational anisotropies, thus providing novel insights otherwise unattainable on microstructural alterations in WM.","journal":"bioRxiv (Cold Spring Harbor Laboratory)","year":2022,"id":311431,"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":0.9585,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2022-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":536401,"name":"Yuxi Pang","orcid":"0000-0001-5039-0236","position":0,"is_corresponding":true}],"reference_count":59,"raw_metadata":null,"created_at":"2026-07-19T00:33:28.480200Z","pmid":null,"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":[]}