Cardiac gating calibration by the Septal Scout for magnetic resonance coronary angiography
Bibliographic record
Abstract
BACKGROUND: Electrocardiogram (ECG) gating is commonly used to synchronize imaging windows to diastasis periods over multiple heartbeats in magnetic resonance (MR) coronary angiography. Calibration of the ECG gating parameters is typically based on a cine cardiovascular MR (CMR) video of the beating heart. Insufficient temporal resolution in the cine-CMR method, however, may produce gating errors and motion artifacts.It was previously shown that tissue Doppler echocardiography (TDE) can identify accurate diastasis window timings by observing the movement of the interventricular septum (IVS). We present a new CMR technique, the Septal Scout, for measuring IVS motion. We demonstrate that cardiac gating windows determined by the Septal Scout produce sharper coronary MR angiography images than windows determined by cine-CMR. METHODS: 9 healthy volunteers were scanned on a GE Optima 450w 1.5T MR system. Cine-CMR was acquired and used to identify the start and end times of the diastasis window (Wcine). The Septal Scout employs a one-dimensional steady-state free precession (SSFP) readout along the ventricular septum prescribed from the 4-chamber view. The Septal Scout data is processed to produce a septal velocity function, from which the diastasis window was determined (Wsep). Non-contrast-enhanced MR angiography was performed twice for each volunteer: once gated to Wcine, once to Wsep. Vessel sharpness was assessed subjectively by two experienced observers, and quantitatively by full width half maximum (FWHM) measurements of cross-sectional vessel profiles. In addition, TDE was performed on a subcohort of 6 volunteers where diastasis windows (WTDE) were determined from the IVS velocity measured in the 4-chamber view. Wsep and WTDE were compared using Pearson's correlation. RESULTS: MRA acquisitions were successful in all volunteers. Vessel segments produced smaller FWHM measurements and were deemed sharper when imaged during the Septal Scout gating windows (p < 0.05). Subjective assessment of sharpness also improved for the Septal Scout-gated scans (p < 0.01 for both observers). Lastly, Wsep and WTDE were highly correlated (R > 0.98, p < 0.001). CONCLUSIONS: The MR Septal Scout technique was introduced and demonstrated to be more accurate at determining cardiac gating windows than cine-CMR, yielding sharper coronary MR angiography images.
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How this classification was reachedexpand
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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".