The effect of pre-activation vial temperature on the acoustic properties of definity
Bibliographic record
Abstract
Definity™ is a widely available clinically approved ultrasound contrast agent. The manufacturer's instructions indicate that the refrigerated vial should be allowed to reach room temperature prior to its 45 second mechanical agitation activation process. Activation results in vial heating, and it has been previously observed that ‘smaller’ bubbles are formed later in this process (> 10 seconds) when the vial temperature is elevated. The objective of this work was to examine the effects of initial vial temperature on the size distribution, frequency dependent attenuation (1.5–27 MHz) and nonlinear imaging performance of Definity™. Experiments were conducted with vials at refrigerator temperature (2°C), room temperature (22°C), or 37°C at the outset of the activation procedure. The size distributions were found to be strongly dependent on initial vial temperature, and the attenuation results indicated considerable differences in the frequency response of the agent, most notably the appearance of a peak at 4 MHz for the 2°C case. Nonlinear imaging results performed with a wall-less vessel phantom indicated that 2°C vials produced an enhancement 4.6 dB greater than for 22°C Definity™ (p < 0.03). These results therefore indicate that not permitting the vial to reach room temperature has a considerable impact on the imaging performance of Definity™. Conversely, activating a cooled vial can provide a means by which to improve contrast enhancement when using low frequency clinical transducers.
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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 | 0.002 |
| 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) | 0.002 | 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".