{
  "abstract": "BackgroundCerebrovascular reactivity (CVR) is a sensitive marker of vascular health, most commonly measured with BOLD fMRI during hypercapnic gas challenges. Hypoxia is a complementary but under-characterized vasoactive stimulus. We characterize a combined hypercapnic-hypoxic gas-challenge paradigm at 7 Tesla BOLD fMRI and its cross-session reproducibility.\n\nMethodsEleven healthy adults were scanned twice at 7 Tesla during an 18-minute multi-echo, multiband BOLD acquisition, receiving fixed-inspired hypercapnic (5% CO2) and hypoxic (10% O2) gas boluses separated by medical-air recovery periods, with end-tidal gas and peripheral saturation monitoring. Hypercapnic and hypoxic CVR were estimated using three trace-based general linear models -- end-tidal gas, peripheral saturation, and Severinghaus-derived arterial saturation -- and a finite impulse response model. Cross-session reproducibility was assessed by region-of-interest intraclass correlation.\n\nResultsThe paradigm produced robust, condition-specific gray-matter BOLD responses that reproduced across sessions. The Severinghaus-derived saturation regressor generalized significantly better than end-tidal and peripheral regressors under cross-session validation and outperformed the finite impulse response model in 58% of gray-matter voxels. Reproducibility across cortical, subcortical, and brainstem atlases was moderate-to-high (median cortical intraclass correlation 0.71).\n\nConclusionA combined hypercapnic-hypoxic paradigm yields reproducible voxelwise cerebrovascular reactivity maps at 7 Tesla; Severinghaus-derived arterial saturation is the most generalizable regressor for hypoxic reactivity.",
  "abstract_shown": true,
  "affiliations": [
    "McGill University, Department of Biological and Biomedical Engineering"
  ],
  "article_type": "PUBLISHAHEADOFPRINT",
  "arxiv": null,
  "author_total": 8,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "S. LoParco"
    },
    {
      "name": "M. Miedema"
    },
    {
      "name": "G.-Y. Choi"
    },
    {
      "name": "M. Sayeh"
    },
    {
      "name": "J. Wang"
    },
    {
      "name": "M. H. Boudrias"
    },
    {
      "name": "G. Mitsis"
    },
    {
      "name": "R. Hoge"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/2e2mamkv91kqn.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.09.11.26362747",
  "fulltext_url": "https://www.medrxiv.org/content/10.64898/2026.09.11.26362747v1.full",
  "id": "2e2mamkv91kqn",
  "issns": [],
  "landing_url": "https://www.medrxiv.org/content/10.64898/2026.09.11.26362747v1",
  "language": null,
  "licence": "CC-BY-NC-ND",
  "licence_label": "CC BY-NC-ND",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "medrxiv",
      "radiology and imaging"
    ],
    [
      "openalex",
      "2741|Advanced MRI Techniques and Applications"
    ]
  ],
  "openalex": "W7212447815",
  "pdf_url": "https://www.medrxiv.org/content/10.64898/2026.09.11.26362747v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-11",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/2e2mamkv91kqn.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:30Z",
      "native_id": "10.64898/2026.09.11.26362747",
      "source": "medrxiv",
      "url": "https://www.medrxiv.org/content/10.64898/2026.09.11.26362747v1"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "medrxiv:radiology and imaging",
      "subfield": "imaging"
    }
  ],
  "title": "Cerebrovascular Reactivity to Hypoxic and Hypercapnic Gas Challenges Using 7T BOLD fMRI",
  "title_text": "Cerebrovascular Reactivity to Hypoxic and Hypercapnic Gas Challenges Using 7T BOLD fMRI",
  "type": "preprint",
  "updated_at": "2026-10-30T12:18:30Z",
  "url": "https://research.draconitic.com/paper/2e2mamkv91kqn",
  "venue": "medRxiv",
  "versions": []
}