1614not just 2d but also 4d flow measurements in pulsatile phantom are accurate and reproducible
Bibliographic record
Abstract
Introduction: 4DFlow is an emerging technique with high potential in the evaluation of congenital and acquired heart diseases. The validation of accuracy and reproducibility of flow measurements in 4DFlow is of key importance for the clinical use of this technique. Here, we compare 2D and 4DFlow using a robust pulsatile flow phantom setup with different tube configurations and heart rates. Methods:Acquisition: A closed-circuit pulsatile flow phantom was built; composed by an industrial membrane flow pump, two counter-flow parallel silicone tubes (inflow tube at isocenter and center of FoV and outflow tube out of isocenter) and a Coriolis flow meter (Endress + Hauser), to measure a ground-truth net flow measure with a precision of about ±1ml/s. Two configurations were tested: 1) with tubes parallel to the z axis of the scanner (axial), and 2) with tubes placed in a double oblique. Flow phantom scans were performed on a GE 3T MR750w MR scanner (Waukesha, WI). Retrospectively gated PC; “breathhold” and “free-breathing” (with 3 averages) 2D through-plane FastCINE and kat ARC 4D Flow were scanned [1]. Table 1 summarizes the flow phantom configuration setups and the main MRI protocol parameters. Analysis: PC net flow measurements were evaluated using CVI42 software (Calgary, Canada) for 2D and Arterys (San Francisco, CA) for 4DFlow. For both, background phase correction (BPC) using static phantom correction [2] and image-based correction [3] was applied. Statistical analyses were performed in Microsoft Excel. Intraclass Correlation Coefficients (ICC) was used to evaluate reproducibility. The Bland-Altmann plot was used to compare the obtained net flow results using MR to the ground-truth value measured by the flow meter in percentage difference as a measure of accuracy. Results: At the position of the outflow tube (>8cm from isocenter) before BPC the highest background phase error of 13% for the lower VENC was found. However, Figure 1 shows a mean percentage error of less than 8% (less than 6% for 4DFlow) with respect to the ground-truth flow for both tubes and for all configurations after BPC. Reproducibility was excellent obtaining ICC = 0.97 for 20 datasets. Discussion: 2D PC and 4DFlow across multiple imaging conditions and setup configurations for a pulsatile flow phantom setup are reliable and accurate. References: 1. Lai P et al. ISMRM 2015. 2. Chernobelsky et al. 2007. 3. Tan et al. ISMRM 2014. JOURNAL/ehjci/04.02/01619449-201605001-00214/math_214MM1/v/2017-10-13T061416Z/r/image-png JOURNAL/ehjci/04.02/01619449-201605001-00214/math_214MM2/v/2017-10-13T061416Z/r/image-png JOURNAL/ehjci/04.02/01619449-201605001-00214/math_214MM3/v/2017-10-13T061416Z/r/image-png
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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 | 0.003 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".