Imaging diseases of the aorta by MRI: a cost-effectiveness analysis of contrast-enhanced studies compared to non-contrast enhanced angiographic studies
Bibliographic record
Abstract
Free-breathing, ECG-triggered, navigator-gated 3D segmented steady state free precession (SSFP) MRA is a promising MR technique for imaging the thoracic aorta. We wanted to establish the economic impact of using non-contrast enhanced angiography (non-CEMRA) in our unit compared to the same time period last year when only CEMRA was used. Over a 3 month period, 22% of referrals to our cardiac MRI unit (Siemens Aera©, Erlangen, Germany) were for diseases of the aorta. These patients were divided into 5 subsets: 1) familial screening (Marfans, Turners, etc), 2) dilatation, 3) follow-up aortic dissection, 4) congenital aortic and valve disease & 5) vasculitis. 80 data sets for patients referred for evaluation of their aorta were examined. These were compared with 80 data sets in patients with aortic disease imaged in a similar period when only CEMRA was available. Clinical evaluation included recording the patients' serum creatinine, correlation with aortic measurements from previous imaging studies and subjective assessment of image quality. Cost analysis included costs of contrast agent, power injector sets and routine consumable costs associated with intravenous access. The unit price for consumables for thoracic aortic CEMRA was estimated at $140CAD*/patient ($110CAD for Gadolinium and $30CAD for other disposables). Vasculitis patients (group 5) were excluded from both data sets as intravenous contrast was needed for delayed enhancement imaging. No patient was excluded from CE-angiography due to a high serum creatinine (eGFR in all patients ≥ 30mls/min). No patient undergoing non-CEMRA required an additional CEMRA for a non-diagnostic study. We examined 75 data sets in the 'pre-navigator' group and 72 in the 'post-navigator' group. In the pre-navigator group, 50 patients (67%) underwent CEMRA as part of their examination: 9/12 (75%) group 1, 12/28 (43%) group 2, 2/3 (67%) group 3 and 27/32 (84%) group 4. In the post-navigator group, 14 patients (19%) underwent CEMRA: 5/18 (28%) group 1 (268% reduction), 6/31 (19%) group 2 (266% reduction), 1/5 (20%) group 3 (335% reduction) and 5/18 (28%) group 4 (300% reduction). Costs associated directly with CEMRA in the pre-navigator group were $7000CAD (50 x $140CAD) and in the post-navigator group were $1960CAD (14 x $140CAD), a saving of $5040. *CAD = Canadian dollars. We conclude that using a free-breathing, ECG-triggered, navigator-gated 3D segmented steady state free precession (SSFP) sequence is a cost-effective way of imaging disease of the aorta without compromising imaging quality.
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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 | 0.009 | 0.046 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.004 |
| Bibliometrics | 0.003 | 0.003 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| 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 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".