{
  "abstract": "The lumbar cartilage endplate (CEP) is a short-$T_2^*$ structure whose composition has been linked to disc health. Ultrashort-echo-time (UTE) MRI enables direct CEP visualization, but acceleration and reconstruction may alter quantitative $T_2^*$ even when image quality improves. We evaluated how radial undersampling and reconstruction strategy affect CEP $T_2^*$ fidelity in a fully synthetic setting. A 96 x 96 sagittal lumbar phantom with five CEP levels (ground-truth $T_2^*$: 24, 22, 20, 18, and 16 ms) was simulated with six UTE echoes, eight receive coils, and radial sampling. Acceleration factors $R=1,2,4,6,8$ used 302, 151, 76, 50, and 38 spokes, respectively. Reconstructions were CG-SENSE, joint multi-echo FISTA, and direct model-based estimation from k-space. Twenty independent complex-noise realizations were evaluated per acceleration. Direct model-map RMSE increased from 0.172 ms at $R=1$ to 0.800 ms at $R=4$, 1.472 ms at $R=6$, and 2.256 ms at $R=8$. At $R=4$, joint-FISTA had lower image NRMSE than the direct model (0.132 vs. 0.203), while the direct map had lower level-wise $T_2^*$ RMSE than CG-SENSE and joint-FISTA ROI fits (0.800 vs. 1.448 and 1.288 ms; estimators differed). At $R=8$, CG-SENSE ROI fitting had the lowest $T_2^*$ RMSE (1.501 ms), whereas the direct model showed systematic underestimation (bias, -2.136 ms; CCC, 0.723). Image fidelity and quantitative biomarker fidelity therefore diverged under radial acceleration. In this synthetic framework, $R=4$ was a promising operating point for direct CEP $T_2^*$ mapping, whereas $R=8$ produced substantial bias and spatial instability. Scanner, phantom, and in vivo validation are required before clinical translation.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2611.00005",
  "author_total": 1,
  "authors": [
    {
      "name": "Yousef Riyazifar"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/a7r837zax421h.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2611.00005",
  "fulltext_url": null,
  "id": "a7r837zax421h",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2611.00005",
  "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": null,
  "pdf_url": "https://arxiv.org/pdf/2611.00005",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/a7r837zax421h.ris",
  "sources": [
    {
      "first_seen": "2026-11-03T12:20:59Z",
      "native_id": "2611.00005",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2611.00005"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.med-ph",
      "subfield": "biological-medical"
    }
  ],
  "title": "Quantitative $T_2^*$ Fidelity in Accelerated Radial Ultrashort-Echo-Time MRI of the Lumbar Cartilage Endplate: A Synthetic Computational Validation Study",
  "title_text": "Quantitative T_2^* Fidelity in Accelerated Radial Ultrashort-Echo-Time MRI of the Lumbar Cartilage Endplate: A Synthetic Computational Validation Study",
  "type": "preprint",
  "updated_at": "2026-11-05T15:20:18Z",
  "url": "https://research.draconitic.com/paper/a7r837zax421h",
  "venue": "arXiv",
  "versions": []
}