High-Resolution Breath-Hold Contrast-Enhanced MR Angiography of the Entire Carotid Circulation
Bibliographic record
Abstract
OBJECTIVE: The purpose of this study was to evaluate the effect of breathing on image quality of the aortic arch and carotid vessels during contrast-enhanced MR angiography and to show that high-resolution breath-hold contrast-enhanced MR angiography combined with a timing-bolus technique can produce high-quality images of the entire carotid circulation. MATERIALS AND METHODS: Forty patients underwent high-resolution contrast-enhanced MR angiography on a 1.5-T Magnetom Symphony. A coronal three-dimensional (3D) gradient-echo sequence (TR/TE, 4.36/1.64; flip angle, 25 degrees) with asymmetric k-space acquisition was used. The 136 x 512 matrix yielded voxel sizes of 1.33 x 0.64 x 1.0 mm. A timing-bolus acquisition, orientated in the coronal plane to include the aortic arch, was obtained initially during free-breathing. Twenty milliliters of gadopenetate dimeglumine was injected at 2 mL/sec. Unenhanced and enhanced 3D volumes were recorded. A subtracted 3D set was calculated and subjected to a maximum-intensity-projection algorithm. Half of the patients held their breath during angiography and the other half did not. Aortic arch motion was measured on the timing-bolus acquisition as the distance moved by a single pixel in both the x and y directions. Maximum-intensity-projection MR images were assessed independently by two observers, and vessel sharpness was scored on a scale of 1-5. Sharpness was also assessed quantitatively by generating a signal intensity profile across the aortic arch vessel wall and calculating the average of the upslope and downslope at full-width half maximum. Visualization of carotid branch vessels was scored on a scale of 0-5, and venous contamination was scored on a scale of 0-3. RESULTS: Average in-plane aortic arch movement was 10.3 mm in the x direction and 8.7 mm in the y direction. Quantitative and qualitative sharpness of the aortic arch and great vessel origins was better (p < 0.05) during breath-holding than during non-breath-holding. No difference in the sharpness of the carotid vessels was noted between the two groups. Carotid branch vessels were well visualized from the aortic arch to the intracerebral circulation. The average venous contamination score was 0.56. CONCLUSION: Breath-holding greatly improves the sharpness of the aortic arch and great vessel origins but has no effect on visualization of the carotid vessels. High-resolution breath-hold contrast-enhanced MR angiography can produce high-quality, artifact-free images of the entire carotid circulation from the aortic arch to the intracerebral circulation.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| 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".