11C-6 New Observations on the Anisotropy of Ultrasound Blood Backscatter as a Function of Frequency and Shear Rate
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
It is recognized that biological tissues with orientated structures show an angular dependence in echogenicity. Previous works on ultrasound (US) blood backscattering have pointed out that red blood cell (RBC) aggregates (or rouleaux) had privileged orientations in a tubular flow inducing measurable US anisotropic behaviours, but results are scarce. The non Newtonian blood velocity profile in tube flow may however be seen as an obstacle to the understanding of the anisotropic spatial organization of RBC aggregates. In this study, whole blood was circulated in a Couette flow apparatus, which allowed to predictably modulate the RBC aggregate sizes and orientations, and to quantify their respective effects on the angle dependent backscatter coefficient (BSC). Anticoagulated porcine bloods were adjusted to 40% hematocrit and inserted into the Couette flow apparatus, at 37degC. US data were acquired and analyzed using two broadband focused transducers at 20 MHz and 35 MHz. The BSC was measured at ten different insonification angles from 30deg to 150deg with respect to the direction of the blood flow, for shear rates of 2 s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and 10 s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . A control experiment was also conducted on porcine RBCs suspended in a saline solution (no aggregation). The results indicate no anisotropic effect for the saline suspension and a significant angular dependence for whole blood. At an incident frequency of 20 MHz, the anisotropy was 4.3 dB for a shear rate of 2 s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , while it was 4.6 dB for a shear rate of 10 s"1. Similarly, at an incident frequency of 35 MHz, the anisotropy was 5.1 dB for a shear rate of 2 s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and 6.2 dB for a shear rate of 10 s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . Thus, the higher anisotropic variation at 35 MHz may indicate a better US sensitivity to the rouleaux orientation at that frequency. Furthermore, at a shear rate of 2 s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , the maximum BSC was measured at an angle of 75deg, whereas at a shear rate of 10 s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , it was maximum at an angle of 90deg. These last results suggest that the RBC aggregate orientation is shear rate dependent. In conclusion, the Couette flow system that was employed is a good strategy to predictably control the orientation of RBC aggregates as a function of the shear rate.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.000 | 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 it