Aberrant myocardial sheetlet mobility in hypertrophic cardiomyopathy detected using in vivo cardiovascular magnetic resonance diffusion tensor imaging
Bibliographic record
Abstract
Background: Cardiac diffusion tensor imaging (cDTI) contains information on cross-myocyte components of intramyocardial water diffusion. Assuming these to be constrained by the sheetlet and shear layer microstructure of left ventricular myocardium [ 1 ], we hypothesized that cDTI at two cardiac phases would identify changing sheetlet orientations and abnormalities in hypertrophic cardiomyopathy (HCM). We performed cDTI in vivo at 3 Tesla at end-systole and late-diastole in 11 healthy controls and 11 patients with HCM, with previous late gadolinium enhancement (LGE) for detection of fibrosis. Voxel-wise analysis of diffusion tensors relative to ventricular coordinates showed transmural changes of helix-angle, with no differences between phases or between HCM and controls. In controls, the orientation of the second eigenvector of diffusion (E2A), changed from more wall-parallel in diastole to more wall-perpendicular in systole, in accord with the predicted reorientations of sheetlet populations. HCM hearts showed markedly abnormal global E2A in diastole consistent with impaired relaxation (46.8° vs 24.0° controls, p < 0.001), and minor abnormal global E2A in systole consistent with hypercontraction (63.9° vs 56.4° controls, p = 0.026). In hypertrophic regions, sheetlets retained relatively systolic orientations in diastole, independent of fibrosis, which differed from regions of normal wall thickness (LGE present 57.8°, p = 0.0028, LGE absent 54.8°, p = 0.0022 vs normal thickness 38.1°). In vivo DTI quantifies cross-myocyte diffusion. We are potentially showing impaired in vivo diastolic reorientation of sheetlet populations in HCM, although further investigation is required as myocardial strain is a possible confounder. Current work includes the measurement of 3D strain in all subjects for assessment of contractility and for strain correction of the diffusion tensor [ 2 ]. The persistence of a systolic conformation may provide novel phenotypic insight into diastolic abnormalities arising from sarcomeric dysfunction, with potential therapeutic implications.
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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 | 0.002 |
| 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 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 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".