Two‐dimensional time correlation relaxometry of skeletal muscle in vivo at 3 Tesla
Bibliographic record
Abstract
A hybrid two-dimensional relaxometry (2DR) sequence was used to simultaneously measure both the spin-spin (R2) and spin-lattice relaxation rates (R1) of skeletal muscle in vivo. The 2DR sequence involved a 180 degrees inversion pulse followed by a variable delay time (30 values from 40 to 7000 ms); a projection presaturation (PP) scheme to localize a 16-ml cylindrical voxel; and a CPMG sequence (950 even echoes, effective echo spacing = 1.2 ms, equilibrium time = 12 s). The 2DR data were collected at 3.0 Tesla from the flexor digitorum profundus of eight healthy males, 26 +/- 2 years old. Analysis was performed with a 2D version of the non-negative least-squares algorithm and a one-way ANOVA. All subjects exhibited at least three spin-groups (R2 < 200 s(-1)), designated B, C, and D, with R2 values of 42.7, 26.5, and 8.1 s(-1), and fractional volumes of 52, 35, and 7%, respectively. The R1 values of B and C were similar, congruent with0.7 s(-1), but different from that of D (P < 0.001), which had an R1 of 1.0 s(-1). The results suggest that exchange between B and C ranges from 0.7-16.2 s(-1), while exchange between either of these spin-groups with D is slower. If the data are interpreted with a compartment model, in which spin-groups with short and long R2 values are attributed to extra- and intracellular fluid, respectively, the exchange of water across the cell membrane in living skeletal muscle is slow or intermediate relative to both R1 and R2.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".