{
  "abstract": "Purpose: Free-breathing multi-echo MRI enables hepatic PDFF/R2* quantification without breath-holds, but respiratory motion can affect R2* estimation through motion-induced field variations. We investigated whether respiratory motion sensitivity is reduced at 0.55T versus 3T and developed a time-resolved free-breathing 4D MRI approach without respiratory binning. Methods: A navigator-embedded multi-echo stack-of-stars sequence was implemented. Ten subjects were scanned during free breathing and deliberate bulk motion at both 3T and 0.55T. Data were reconstructed using motion-averaged, motion-resolved, and time-resolved approaches. Quantitative performance was also evaluated in a PDFF/R2* phantom using Cartesian and radial acquisitions. Results: Phantom experiments showed close radial-Cartesian agreement for R2* and PDFF at 3T. At 0.55T, R2* showed good agreement over the low-to-moderate range but higher uncertainty at high R2*, where larger radial-Cartesian PDFF differences were also observed. R2* was substantially less sensitive to respiratory motion at 0.55T than at 3T, whereas PDFF was relatively insensitive at both field strengths. Under bulk motion, time-resolved reconstruction provided robust R2* and PDFF measurements, with particularly high consistency between free-breathing and bulk-motion acquisitions at 0.55T. Conclusion: R2* quantification was less sensitive to respiratory motion at 0.55T than at 3T, while PDFF remained relatively insensitive. Time-resolved reconstruction provided additional robustness to bulk motion. Reduced susceptibility effects at 0.55T and time-resolved reconstruction may provide complementary advantages for motion-robust free-breathing hepatic R2* and PDFF quantification.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.23240",
  "author_total": 8,
  "authors": [
    {
      "name": "Jeffery Wong"
    },
    {
      "name": "Jingjia Chen"
    },
    {
      "name": "Ding Xia"
    },
    {
      "name": "Xiang Xu"
    },
    {
      "name": "Els Fieremans"
    },
    {
      "name": "Dmitry S. Novikov"
    },
    {
      "name": "Hersh Chandarana"
    },
    {
      "name": "Li Feng"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/0j430npryyhev.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.23240",
  "fulltext_url": null,
  "id": "0j430npryyhev",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.23240",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "physics.med-ph"
    ],
    [
      "openalex",
      "2741|Advanced MRI Techniques and Applications"
    ]
  ],
  "openalex": "W7214027930",
  "pdf_url": "https://arxiv.org/pdf/2609.23240",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-19",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/0j430npryyhev.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:19Z",
      "native_id": "2609.23240",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.23240"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.med-ph",
      "subfield": "biological-medical"
    }
  ],
  "title": "Free-Breathing PDFF and R2* Quantification at 0.55T: Reduced Respiratory Motion Sensitivity and a Time-Resolved 4D MRI Approach",
  "title_text": "Free-Breathing PDFF and R2* Quantification at 0.55T: Reduced Respiratory Motion Sensitivity and a Time-Resolved 4D MRI Approach",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:19Z",
  "url": "https://research.draconitic.com/paper/0j430npryyhev",
  "venue": "arXiv",
  "versions": []
}