Kidney Sodium MRI: Extending the Concept of Residual Kidney Function in Hemodialysis
Bibliographic record
Abstract
Background: It is widely recognized that persistence of even modest amount residual kidney function (RKF) is associated with improved outcomes, in hemodialysis (HD) patients. The concept of RKF, as currently utilized, is exclusively based upon urine volume and small solute clearance-requiring complete interdialytic urinary collection. This makes accurate and consistent assessment measurement challenging and difficult to implement in clinical practice. More importantly it focusses almost exclusively on glomerular function, rather than a more inclusive consideration of overall kidney function to incorporate assessment of renal tubular mass. The aim of this study was to test the feasibility of obtaining useable 23Na-MRI kidney images, in the setting of dialysis dependance (as compared to normal subjects without CKD) and initially describe the associations between directly imaged medullary sodium content and other components of a more conventional approach to the definition of RKF. Methods: We included 21 healthy volunteers and 17 HD participants, fasted for eight hours prior to their study visit. Urine samples were collected to measure urinary osmolarity, before MRI scan. Results: Median (IQR) fasting medulla to cortex ratio was significantly higher 1.56 [1.5 - 1.61] in healthy volunteers compared to HD patients 1.22 [1.13 - 1.3], p<0.0001. Medulla to cortex ratio and median urinary osmolarity were correlated (r=0.87, p<0.0001) in the whole population. We found a significant association between HD vintage and medulla to cortex ratio whereas we did not find any association with urine volume. Sodium signal intensity distribution within healthy kidney describes two different peaksrelating to well defined cortex and medulla; whereas HD participants displays only a single peak indicative of the markedly lower sodium concentration. Conclusions: The application of kidney sodium MRI to the study of RKF in patients receiving maintenance HD is practical and provides a previously unavailable ability to interrogate the function of remnant tubular mass.
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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 | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| 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".