Review of Hyperpolarized Pulmonary Functional <scp><sup>129</sup>Xe MR</scp> for <scp>Long‐COVID</scp>
Bibliographic record
Abstract
The respiratory consequences of acute COVID‐19 infection and related symptoms tend to resolve 4 weeks post‐infection. However, for some patients, new, recurrent, or persisting symptoms remain beyond the acute phase and persist for months, post‐infection. The symptoms that remain have been referred to as long‐COVID. A number of research sites employed 129Xe magnetic resonance imaging (MRI) during the pandemic and evaluated patients post‐infection, months after hospitalization or home‐based care as a way to better understand the consequences of infection on 129Xe MR gas‐exchange and ventilation imaging. A systematic review and comprehensive search were employed using MEDLINE via PubMed (April 2023) using the National Library of Medicine's Medical Subject Headings and key words: post‐COVID‐19, MRI, 129Xe, long‐COVID, COVID pneumonia, and post‐acute COVID‐19 syndrome. Fifteen peer‐reviewed manuscripts were identified including four editorials, a single letter to the editor, one review article, and nine original research manuscripts (2020–2023). MRI and MR spectroscopy results are summarized from these prospective, controlled studies, which involved small sample sizes ranging from 9 to 76 participants. Key findings included: 1) 129Xe MRI gas‐exchange and ventilation abnormalities, 3 months post‐COVID‐19 infection, and 2) a combination of MRI gas‐exchange and ventilation abnormalities alongside persistent symptoms in patients hospitalized and not hospitalized for COVID‐19, 1‐year post‐infection. The persistence of respiratory symptoms and 129Xe MRI abnormalities in the context of normal or nearly normal pulmonary function test results and chest computed tomography (CT) was consistent. Longitudinal improvements were observed in long‐term follow‐up of long‐COVID patients but mean 129Xe gas‐exchange, ventilation heterogeneity values and symptoms remained abnormal, 1‐year post‐infection. Pulmonary functional MRI using inhaled hyperpolarized 129Xe gas has played a role in detecting gas‐exchange and ventilation abnormalities providing complementary information that may help develop our understanding of the root causes of long‐COVID. Level of Evidence 1 Technical Efficacy Stage 5
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.012 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.005 | 0.004 |
| Bibliometrics | 0.010 | 0.010 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".