Abstract 60: Multiphase versus Single Phase CT Angiography for Detection of Distal Intracranial Occlusion
Bibliographic record
Abstract
Introduction: Detecting distal intracranial arterial occlusion is of increasing importance as current studies begin to evaluate the potential benefit of tPA in minor acute stroke. Multiphase CTA (mCTA) is a technique used routinely at our centre in the setting of suspected acute ischemic stroke (AIS). Hypothesis: We hypothesized that mCTA is diagnostically superior to CTA for detection of distal intracranial arterial occlusion in suspected AIS. Methods: Population comprised of patients with suspected AIS who had mCTA, followed by MR brain with DWI within 24 hours. mCTA involves 3 phases of enhanced CT from skull base to vertex following administration of a single iodinated contrast bolus. Prospective interpretation of unenhanced CT followed by single phase CTA was performed by a radiology resident, a stroke fellow, or a neuroradiologist. Unenhanced CT followed by mCTA was interpreted > 1 week after single phase CTA interpretation using the same dataset. MR exams were separately adjudicated to establish each case as positive or negative according to pre-specified criteria that suggests a high likelihood for the presence of an arterial occlusion on CTA (DWI lesion > 2mm diameter, not multiple small infarcts consistent with microembolic shower, not exclusively white matter lesion, not small deep gray matter lesion consistent with lacunar type infarct. Results and Conclusion: Of 322 patients, single phase CTA detected 69 occlusions (sensitivity 52.5%, specificity 98.1%) and mCTA detected 113 (sens = 81.8%, spec = 99.5%). mCTA detected a greater number of proximal occlusions (76 vs. 66), and a greater number of distal occlusions (37 vs. 3) than CTA. mCTA demonstrated a greater rate of detection for distal occlusions (relative rate = 9.67, 95% CI 3.76 - 24.84). CTA/MR agreement was moderate (kappa = 0.59) while mCTA/MR agreement was substantial (kappa = 0.81). Mean interpretation time for CTA was 239.8 seconds (95% CI 221.3 - 258.4) and 195.0 seconds (95% CI 176.9 - 213.1) for mCTA. In conclusion, our data suggest mCTA is superior to single phase for detection of distal intracranial occlusion.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.004 | 0.011 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 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".