P187The role of cardiovascular magnetic resonance imaging in assessing heart failure with a short, contrast-agent free protocol
Bibliographic record
Abstract
OnBehalf: MUHC CMR Group INTRODUCTION: Heart Failure (HF) is the leading cause of cardiovascular morbidity, mortality, and health care use. New technological developments, including the use of T1 and T2-imaging to assess tissue characterization, in Cardiovascular Magnetic Resonance Imaging (CMR) has led to reduced scan times. The potential for contrast-agent free protocols have further been made possible through Oxygenation-Sensitive CMR (OS-CMR) in combination with standardized breathing maneuvers, which has been established as a potential marker for microvascular function. PURPOSE: The aim of this study was to assess the time of a contrast-free protocol for routine clinical heart failure assessment. METHODS: Twelve heart failure patients (mean age 64 ± 9 years; 36% female) and fourteen age-matched healthy volunteers (mean age 56 ± 5 years; 64% female) underwent a CMR on a clinical 3T scanner (Skyra, Siemens, Erlangen, Germany). The short, contrast-free CMR protocol included standard cine sequences for ventricular function (short axis stack), T1 mapping (MOLLI, short axis view), T2 mapping (FLASH, short axis view), and OS-CMR (in basal and mid-ventricular short axis views). Strain values were obtained using the standard cine short-axis views and the 2- and 4-chamber long-axis images. The global myocardial oxygenation reserve (MORE) was obtained from OS-CMR images at baseline and during a long breath-hold that was preceded by a 60s period of hyperventilation. Time of scan was determined from the first and last sequences performed. RESULTS: Compared with the control group, patients with HF had, on average, a higher global T1 (p < 0.0001), higher global T2 (p = 0.0009), larger end-diastolic volume (p = 0.0005), larger end-systolic volume (p < 0.0001), larger left-ventricular end-diastolic atrial volume (p = 0.0016) and lower left-ventricular ejection fraction (p < 0.0001), with a reduced global peak systolic circumferential strain (<0.0001), and global peak systolic longitudinal strain (p < 0.0001). In patients, the breathing-induced MORE was also significantly lower than in healthy controls (0.3 ± 3.3 vs 4.5 ± 4.2, p = 0.013). The study protocol was significantly shorter (p < 0.0001) than the current clinical MRI protocol, 49.3 ± 10.7 and 31.4 ± 8.3 minutes, respectively. CONCLUSION: A significantly shorter, contrast-free CMR protocol of 31- compared to the standard 49-minute protocol was able to determine that heart failure patients were characterized by functional, mapping, and strain CMR parameters as well as impaired coronary microvascular function, that could be detected by OS-CMR.
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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 | 0.005 | 0.008 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.002 |
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".