MRI Phase-Contrast Blood Flow in Fasting Pediatric Patients with Fontan Circulation Correlates with Exercise Capacity
Bibliographic record
Abstract
Purpose To assess regional blood flow in fasting pediatric patients with Fontan circulation by using MRI and to explore associations with clinical parameters. Materials and Methods In this retrospective study, pediatric patients who had undergone the Fontan procedure (<18 years of age) and had undergone clinical cardiac MRI, performed after at least 4 hours of fasting, between 2018 and 2021 were included. Regional blood flow was compared with published healthy volunteer data (n = 19) and assessed in relation to hemodynamic parameters and clinical status. Data are presented as medians, with first to third quartiles in parentheses. Mann-Whitney U, Kruskal-Wallis, χ2, and Spearman rank correlation tests were used. Results Fifty-five patients (38 boys) with median age at MRI of 14 years (IQR, 11–16 years) and median time from Fontan procedure to MRI of 10 years (IQR, 8–12 years) were included. Patients after Fontan procedure had lower ascending aortic, inferior vena cava, and total systemic blood flow compared with healthy volunteers (3.00 L/min/m2 [IQR, 2.75–3.30 L/min/m2] vs 3.61 L/min/m2 [IQR, 3.29–4.07 L/min/m2]; 1.73 L/min/m2 [IQR, 1.40–1.94 L/min/m2] vs 2.24 L/min/m2 [IQR, 2.06–2.75 L/min/m2]; 2.78 L/min/m2 [IQR, 2.45–3.10 L/min/m2] vs 3.95 L/min/m2 [IQR, 3.20–4.30 L/min/m2], respectively; P < .001). Portal vein flow was greater than hepatic vein flow in 25% of patients. Fontan blood flow was inversely correlated with pre-Fontan mean pulmonary artery pressure (Spearman rank correlation coefficient [rs]= −0.42, P = .005) and ventricular end diastolic pressure (rs = −0.33, P = .04) and positively correlated with post-Fontan percent predicted oxygen consumption at peak workload (rs = 0.34, P = .02). Conclusion Reference ranges are provided for regional systemic blood flow derived by using MRI in fasting pediatric patients with Fontan circulation, who had lower systemic blood flow compared with healthy volunteers. Lower fasting Fontan blood flow correlated with lower exercise capacity. Keywords: Pediatrics, Heart, Congenital, MR Imaging, Hemodynamics/Flow Dynamics, Cardiac Supplemental material is available for this article. © RSNA, 2022
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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 | 0.000 | 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) | 0.001 | 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".