The use of pressure dependent subharmonic resonance to increase the signal to noise ratio of ultrasound contrast agent imaging.
Bibliographic record
Abstract
Conventional methods of subharmonic (SH) imaging of ultrasound contrast agents (UCAs) employ a frequency which is approximately twice the resonance frequency of the UCA (the SH resonance frequency). However, this approach may be limited by a low signal to noise ratio. To address this problem, the Hoff model was solved for several UCAs and the SH resonance frequencies of the bubble were calculated for different applied pressures (PAs). By increasing the PA above the pressure threshold for SH generation, the SH resonance frequency shifts toward lower values. Calculation of the scattered pressure in the regime of stable oscillations show that, if the bubble is sonicated with its pressure dependent SH resonance frequencies, the backscattered signal can be significantly stronger than when sonicating with the conventional SH resonance frequency (although the initiation of the SH occurs at a higher PA). The enhancement of the SH and ultraharmonic amplitudes can be up to 7 and 14 dB, respectively. This enhancement may lead to better UCA SH imaging, especially for molecular based imaging protocols.
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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 | 0.001 | 0.001 |
| 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".