Assessing photoplethysmographic imaging performance beyond facial perfusion analysis
Bibliographic record
Abstract
Photoplethysmographic imaging (PPGI) systems are relatively new non-contact biophotonic diffuse reflectance systems able to assess arterial pulsations through transient changes in light-tissue interaction. Many PPGI studies have focused on extracting heart rate from the face or hand. Though PPGI systems can be used for widefield imaging of any anatomical area, whole-body investigations are lacking. Here, using a novel PPGI system, coded hemodynamic imaging (CHI), we explored and analyzed the pulsatility at major arterial locations across the whole body, including the neck (carotid artery), arm/wrist (brachial, radial and ulnar arteries), and leg/feet (popliteal and tibial arteries). CHI was positioned 1.5 m from the participant, and diffuse reactance from a broadband tungsten-halogen illumination was filtered using 850{1000 nm bandpass filter for deep tissue penetration. Images were acquired over a highly varying 24-participant sample (11/13 female/male, age 28.7±12.4 years, BMI 25.5±5.2 kg/m<sup>2</sup>), and a preliminary case study was performed. B-mode ultrasound images were acquired to validate observations through planar arterial characteristics.
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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 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 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".