Hyperpolarized Helium 3 MRI in Mild-to-Moderate Asthma: Prediction of Postbronchodilator Reversibility
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Bibliographic record
Abstract
Background Longitudinal progression to irreversible airflow limitation occurs in approximately 10% of patients with asthma, but it is difficult to identify patients who are at risk for this transition. Purpose To investigate 6-year longitudinal changes in hyperpolarized helium 3 (3He) MRI ventilation defects in study participants with mild-to-moderate asthma and identify predictors of longitudinal changes in postbronchodilator forced expiratory volume in 1 second (FEV1) reversibility Materials and Methods Spirometry and hyperpolarized 3He MRI were evaluated in participants with mild-to-moderate asthma in two prospectively planned visits approximately 6 years apart. Participants underwent methacholine challenge at baseline (January 2010 to April 2011) and pre- and postbronchodilator evaluations at follow-up (November 2016 to June 2017). FEV1 and MRI ventilation defects, quantified as ventilation defect volume (VDV), were compared between visits by using paired t tests. Participants were dichotomized by postbronchodilator change in FEV1 at follow-up, and differences between reversible and not-reversible groups were determined by using unpaired t tests. Multivariable models were generated to explain postbronchodilator FEV1 reversibility at follow-up. Results Eleven participants with asthma (mean age, 42 years ± 9 [standard deviation]; seven men) were evaluated at baseline and after mean 78 months ± 7. Medications, exacerbations, FEV1 (76% predicted vs 76% predicted; P = .91), and VDV (240 mL vs 250 mL; P = .92) were not different between visits. In eight of 11 participants (73%), MRI ventilation defects at baseline were at the same location in the lung at follow-up MRI. In the remaining three participants (27%), MRI ventilation defects worsened at the same lung locations as depicted at baseline methacholine-induced ventilation. At follow-up, postbronchodilator FEV1 was not reversible in six of 11 participants; the concentration of methacholine to decrease FEV1 by 20% (PC20) was greater in FEV1-irreversible participants at follow-up (P = .01). In a multivariable model, baseline MRI VDV helped to predict postbronchodilator reversibility at follow-up (R 2 = 0.80; P < .01), but PC20, age, and FEV1 did not (R 2 = 0.63; P = .15). Conclusion MRI-derived, spatially persistent ventilation defects predict postbronchodilator reversibility 78 months ± 7 later for participants with mild-to-moderate asthma in whom there were no changes in lung function, medication, or exacerbations. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Stojanovska in this issue.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 it