Abstract W P31: Does Portable CT Imaging in a Mobile Stroke Treatment Unit (MSTU) Provide Adequate Quality for Early Critical Decision Making?
Bibliographic record
Abstract
BACKGROUND: Our hospital implemented a Mobile Stroke Treatment Unit (MSTU) on July 18, 2014 involving a pre-hospital delivery of stroke thrombolysis. The MSTU team evaluates potential IV tPA candidates using a portable CT head (pCTH) scan in the field. OBJECTIVE: To determine adequacy of MSTU CT quality for early ischemic changes and IV tPA administration. METHODS: A retrospective analysis was performed of patients approached by MSTU who received a pCTH (CereTom, Neurologica, Danvers, MA). Assessment of quality, artifacts, physician confidence and findings (intracranial hemorrhage (ICH), early ischemic changes using Alberta Stroke Program Early CT score (ASPECTS)) was performed. Two neurologists with ASPECTS certification and blinded to patient history reviewed images independently. Inter-rater agreement and Spearman’s correlation of numeric variables between the two reviewers were compared. For comparison inter-rater reliability, control CT scans performed in emergency department (ED) for early stroke evaluation in different sets of 20 patients were assessed by two reviewers. RESULTS: A total of 23 patients underwent pCTH in the MSTU since initiation. Two patients were found to have ICH, later confirmed by a standard hospital CT scan. The remaining 21 patients did not have any evidence of ICH, 10 (48%) of whom had a subsequent hospital CT or MRI confirming absence of ICH. pCTH quality was assessed to be adequate in 18 (85%) subjects by both reviewers to make decisions on thrombolysis treatment. CT artifacts were noted in 15 (71%) scans by reviewer 1 and 16 (76%) scans by reviewer 2 (k 0.4, p=0.2). ASPECTS on pCTH did not have high correlation between two raters (spearman’s rho=0.3, p=0.1). Confidence of ASPECTS was low in both reviewers (52% reviewer 1 vs 66% reviewer 2). In comparison, correlation between ED controls was better between the two reviewers (spearman’s rho= 0.6, p=0.01). Confidence of ASPECT score was high for both reviewers in the control group (95% reviewer 1; 100% reviewer 2). Artifacts were noted in few scans of controls (n=5, 25% reviewer 1; n=3, 15%, reviewer 2). CONCLUSION: The quality of pCTH on the MSTU is adequate for thrombolysis contraindications, but artifacts are common and subtle early ischemic changes are difficult to assess.
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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 | 0.006 | 0.050 |
| 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 | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".