Optimally Repeatable Kinetic Model Variant for Myocardial Blood Flow Measurements with <sup>82</sup>Rb PET
Bibliographic record
Abstract
Purpose. Myocardial blood flow (MBF) quantification with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">R</mml:mi><mml:mi mathvariant="normal">b</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn mathvariant="normal">82</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> positron emission tomography (PET) is gaining clinical adoption, but improvements in precision are desired. This study aims to identify analysis variants producing the most repeatable MBF measures. Methods. 12 volunteers underwent same-day test-retest rest and dipyridamole stress imaging with dynamic <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">R</mml:mi><mml:mi mathvariant="normal">b</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn mathvariant="normal">82</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> PET, from which MBF was quantified using 1-tissue-compartment kinetic model variants: (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mrow><mml:mn fontstyle="italic">1</mml:mn></mml:mrow></mml:math>) blood-pool versus uptake region sampled input function (Blood/Uptake-ROI), (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mrow><mml:mn fontstyle="italic">2</mml:mn></mml:mrow></mml:math>) dual spillover correction (SOC-On/Off), (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:mrow><mml:mn fontstyle="italic">3</mml:mn></mml:mrow></mml:math>) right blood correction (RBC-On/Off), (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M6"><mml:mrow><mml:mn fontstyle="italic">4</mml:mn></mml:mrow></mml:math>) arterial blood transit delay (Delay-On/Off), and (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M7"><mml:mrow><mml:mn fontstyle="italic">5</mml:mn></mml:mrow></mml:math>) distribution volume (DV) constraint (Global/Regional-DV). Repeatability of MBF, stress/rest myocardial flow reserve (MFR), and stress/rest MBF difference (ΔMBF) was assessed using nonparametric reproducibility coefficients (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M8"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">R</mml:mi><mml:mi mathvariant="normal">P</mml:mi><mml:mi mathvariant="normal">C</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">n</mml:mi><mml:mi mathvariant="normal">p</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math> = 1.45 × interquartile range). Results. MBF using SOC-On, RVBC-Off, Blood-ROI, Global-DV, and Delay-Off was most repeatable for combined rest and stress: <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M9"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">R</mml:mi><mml:mi mathvariant="normal">P</mml:mi><mml:mi mathvariant="normal">C</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">n</mml:mi><mml:mi mathvariant="normal">p</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math> = 0.21 mL/min/g (15.8%). Corresponding MFR and ΔMBF <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M10"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">R</mml:mi><mml:mi mathvariant="normal">P</mml:mi><mml:mi mathvariant="normal">C</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">n</mml:mi><mml:mi mathvariant="normal">p</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math> were 0.42 (20.2%) and 0.24 mL/min/g (23.5%). MBF repeatability improved with SOC-On at stress (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M11"><mml:mi>p</mml:mi><mml:mo><</mml:mo><mml:mn fontstyle="italic">0.001</mml:mn></mml:math>) and tended to improve with RBC-Off at both rest and stress (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M12"><mml:mi>p</mml:mi><mml:mo><</mml:mo><mml:mn fontstyle="italic">0.08</mml:mn></mml:math>). DV and ROI did not significantly influence repeatability. The Delay-On model was overdetermined and did not reliably converge. Conclusion. MBF and MFR test-retest repeatability were the best with dual spillover correction, left atrium blood input function, and global DV.
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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 | 0.005 | 0.015 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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".