BOLD MRI at 1.5 Tesla in juvenile idiopathic arthritis: preliminary experience
Bibliographic record
Abstract
BOLD MRI contrast results from changes in the microvascular ratio of oxyhemoglobin (oxyHb) to deoxyhemoglobin (deoxyHb) (1). DeoxyHb is paramagnetic, which results in a local bulk magnetic susceptibility effect and subsequent MRI signal change in T(2)*-weighted functional MRI scans (1). Although BOLD contrast has been studied extensively in functional MRI studies of the brain, limited investigation has been performed in other tissues. Juvenile idiopathic arthritis (JIA) is the most common rheumatic disorder of childhood (2), with the knee being the most frequently affected joint (3). With the increasing availability and use of disease-modifying and antirheumatic biologic drugs for the treatment of JIA (4), the early determination of joint abnormality has become extremely important. Given the lack of clinical and laboratory tests that enable the functional evaluation of perisynovial oxygenation in JIA, the use of BOLD MRI to measure early soft tissue physiological imbalances due to hypoxia is appealing (5). In inflammatory arthritis, the increased metabolic demand of the inflamed synovium and the inadequate delivery of oxygen caused by poor perfusion through the inflamed synovium (5) result in hypoxia within the inflamed joint in the acute stage of arthritis. Consequently, the synovial blood flow increases to compensate for the hypoxic status of the joint. In JIA, despite the local hyperemia, the synovial capillaries develop an abnormal oxygen transportation capability (5,6), which may result in abnormal concentrations of oxyHb and deoxyHb at the capillary level. To date, no single imaging assay or surrogate marker has been demonstrated to adequately reflect the spectrum of metabolic events involved in inflammatory arthritis. We hypothesized that BOLD MRI would be able to reflect the state of oxygenation in the microcirculation of periarticular tissues in JIA children at 1.5 Tesla as previously shown for other pathological states (7). Previous studies of our group in rabbit models of inflammatory arthritis demonstrated the feasibility (8), criteria validity (9), interframework reliability for data acquisition (10), combination of region-of-interest (ROI)-related reading parameters that provide the highest accuracy for discrimination of the presence or absence of arthritis in acute and subacute stages of the disease (11), and responsiveness of the technique to short-term joint temperature changes (12). However, no previous study has demonstrated whether the BOLD MRI technique is able to differentiate inflammatory from healthy perisynovial tissue at 1.5 Tesla and determine interval soft tissue changes as a result of intraarticular corticosteroid injections in the knees of JIA patients. In the present paper, we describe the BOLD MRI methodology and preliminary results on the feasibility of using BOLD MRI at 1.5 Tesla to measure the responsiveness (sensitivity to change) of the interval of soft-tissue changes in JIA patients with unilateral knee arthritis following intraarticular injection of corticosteroids as a proof of concept. We knew in advance the expected effectiveness of the injection procedure, which reduces synovial inflammation in JIA in approximately 76% of cases at 6 weeks after the injection (13).
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".