Abstract 16863: Cardiac Magnetic Resonance T1 Mapping as a Window Into the Myocardium in Friedreich Ataxia
Bibliographic record
Abstract
Introduction: Left ventricular (LV) remodeling and hypertrophy are common findings in Friedreich Ataxia (FA) and associated with a poorer prognosis. Cardiac magnetic resonance (CMR) T1 mapping, a technique used to assess myocardial fibrosis, may be able to identify cardiomyopathic changes in FA at an early stage of the cardiac disease process. We hypothesized that T1 mapping variables would demonstrate myocardial involvement in FA independently of the recognized LV structural and functional changes. Methods: A standardized CMR protocol including T1 mapping and measurements of LV mass, LV end-diastolic volume, native T1 time, post gadolinium (PostGad) T1 time, and calculation of the LV mass/volume ratio (LVMVR), partition coefficient (PC), and extracellular volume (ECV) was performed at two sites on FA subjects who were homozygous for GAA repeats in the FXN gene. GAA repeat length in the shorter allele (GAA1) of the frataxin gene ( FXN ) was used as a surrogate for the degree of frataxin deficiency. Results: Ninety-five FA subjects (56% males, median age 22 yrs, age of onset 10 yrs, GAA1 700) were scanned. Nine FA subjects had a LV ejection fraction (EF) <55%; their T1 variables were not different than those with preserved LVEF. Fifty-three subjects had an elevated LVMVR (>1.20); their T1 variables were not different from those without an elevated LVMVR. On multivariate analysis, GAA1 correlated with native T1 time (p=0.009), PostGad T1 time (p=0.003), PC (p<0.001), and ECV (p<0.001) after adjusting for sex, age and site. LVMVR was a correlate of native T1 time when adjusted for sex, age and site (p=0.019), but not when also adjusted for GAA1, whereas GAA1 still predicted native T1 when adjusted for sex, age, site, and LVMVR (p=0.018). Conclusion: T1 mapping provides information about the myocardium in FA which is correlated with the degree of frataxin deficiency and is independent of LV remodeling. Study of the relationship between T1 variables and cardiac outcomes is now needed to help determine the utility of this technique as a monitoring and prognostic biomarker for this rare disease.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.003 | 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 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".