Quantitative renal PET imaging with Rubidium-82 can discriminate individuals with different degrees of renal impairment
Bibliographic record
Abstract
164 Background: While non-invasive quantitative (K1) renal imaging with Rubidium-82 (Rb-82) PET has been shown to be feasible in healthy volunteers, its clinical application remains uncertain.Objective:The aim of the study was to investigate changes in renal K1 (as marker of blood flow; quantified in Rb-82 PET images) across various degrees of renal impairment.Methods: We studied 102 patients (mean age 60 ± 12 years; LVEF 62 ± 14%; median creatinine 1.13 mg/dL [IQR 0.89 - 4.58]; male 56%; blacks 44%; diabetes 38%; hypertension 81%; coronary disease 25%; heart failure 15%) who underwent list-mode rest/stress Rb-82 myocardial perfusion PET/CT for evaluation of inducible ischemia, and in whom the right and/or left kidney were partial or fully included in the field of view of the heart. On both the rest and stress delayed images, volumes of interest were drawn along the entire left ventricular (LV) wall, the visualized right and/or left kidneys, and the center of the left atrial blood pool. Tissue and blood pool time activity curves were generated from the dynamic datasets, and a two-compartment model was applied for quantitative evaluation of tracer kinetics at rest and during stress. Results: Patients were divided into 5 groups according to their glomerular filtration rate (GFR): group 1 (n=54; GFR ≥ 60 ml/min/1.73m2), group 2 (n=6; GFR 45-59 ml/min/1.73m2), group 3 (n=5; GFR 30 - 44 ml/min/1.73m2), group 4 (n=3; GFR 15 - 29 ml/min/1.73m2), and group 5 (n=34; GFR <15 ml/min/1.73m2). Overall, renal K1 did not vary between rest and stress (0.83 ± 0.43 vs. 0.84 ± 0.46 ml/min/g; P=0.42) or between the right and left kidney (0.84 ± 0.44 vs. 0.85 ± 0.43 ml/min/g; P=0.42). Renal K1 showed a clear correlation with renal function (r = -0.64; P<0.001) with a stepwise reduction across GFR 1-5 groups (1.12 ± 0.35, 0.93 ± 0.30, 0.68 ± 0.18, 0.49 ± 0.15, 0.44 ± 0.20 mL/min/gr, respectively; P<0.0001). The renal-to-LV K1 ratio showed that flow was significantly higher in the kidney in groups 1 and 2, comparable between organs in group 3, and lower in the kidney than the heart in groups 4 and 5 (1.82 ± 0.54, 1.50 ± 0.27, 1.17 ± 0.56, 0.79 ± 0.25, 0.66 ± 0.25, respectively; P<0.0001).Conclusion:Non-invasive evaluation of renal flow with Rb-82 PET is feasible during cardiac evaluations and can discriminate patients with varying degrees of renal dysfunction. Further studies are necessary to better delineate the relationship between absolute renal blood flow and the perfusion coefficient K1, as well as its predictive role in the development of renal dysfunction.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".