Suspected acute stroke (adult)
Sudden focal neurological deficit. Record the time last known well. Call a code stroke.
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RadiologyDiagnostic
Acute Stroke Imaging Protocol (AHA/ASA)
Acute Stroke Imaging Protocol (AHA/ASA): Suspected acute stroke (adult) → Before the scan: glucose, age under 18, pregnancy → Immediate non-contrast CT ...
Pathway Overview
14 steps
Algorithm Steps
14 total
01Start 02Warning Before the scan: glucose, age under 18, pregnancy
Check these on arrival. Do not delay imaging.
- Check capillary glucose. Treat hypoglycaemia first; it can mimic stroke.
- Under 18 years: this adult pathway does not apply. Use a paediatric stroke pathway.
- Pregnant: do not delay imaging. Thrombolysis only on stroke specialist advice (uterine bleeding risk); consider thrombectomy.
03Action Immediate non-contrast CT brain (or MRI)
Scan at once if reperfusion therapy is possible. All other suspected strokes: urgent scan, preferably within 60 min.
- CT or MRI are both acceptable if available at once. Do not let MRI delay treatment.
- Thin-slice (<2 mm) non-contrast CT shows hyperdense thrombus better.
- Possible reperfusion candidate: do CTA (and CTP if needed) in the same session.
04Decision Haemorrhage on CT?
- If Yes
05End Haemorrhage on CT: no thrombolysis; ICH or SAH pathway
Do not give thrombolysis, antiplatelet or anticoagulant. Reverse any anticoagulant urgently. Get neurosurgical review.
If No06Decision No haemorrhage: time since last known well?
- Within 4.5 h
07Action Within 4.5 h: assess for IV thrombolysis now
Adult with a potentially disabling deficit (any NIHSS score). If eligible, give as early as possible; do not wait for CTA or thrombectomy. Non-disabling deficit (e.g. isolated sensory loss): no thrombolysis; give antiplatelet.
- Do not give if: haemorrhage; clear hypodensity over 1/3 of MCA territory; active bleeding; suspected aortic dissection; infective endocarditis. BP must be below 185/110 mmHg before treatment and kept below that for 24 h after. If it cannot be lowered, do not give.
- Do not give if: INR above 1.7 (including warfarin); platelets below 100 x10^9/L; unfractionated heparin in 48 h with raised APTT; treatment-dose LMWH in 24 h. Do not wait for these results unless anticoagulant use or coagulopathy is suspected. DOAC in last 48 h (or unknown): do not give unless a stroke specialist advises (specific reversal agent first, or thrombectomy if LVO).
- Relative, stroke specialist weighs risk and benefit: previous ICH; intra-axial brain tumour; brain or spinal surgery or major head trauma in 3 months; ischaemic stroke in 3 months; other major surgery or trauma in 14 days; GI or urinary bleed in 21 days.
- Tenecteplase 0.25 mg/kg (max 25 mg) single IV bolus over 5-10 s. Use the 25 mg stroke vial (5 mg/mL); the stroke dose is lower than the heart attack dose. OR alteplase 0.9 mg/kg (max 90 mg) at 1 mg/mL: 10% IV bolus, then the rest over 60 min.
08Action CTA arch to vertex, with CTP if needed
Do CTA for every possible thrombectomy candidate. Do not wait for renal function before giving contrast.
- Do not delay thrombolysis to get CTA or CTP.
- CTA: shows the occlusion site and the access route.
- CTP or MRI: shows core and penumbra; used to select patients beyond 6 h.
- No thrombectomy on site: send images to the thrombectomy centre (telestroke) and arrange transfer.
09Decision Large vessel occlusion (ICA, M1, proximal or dominant M2, basilar, tandem)?
- If Yes
10Action LVO: urgent thrombectomy referral
Thrombectomy if it can start within 24 h of last known well. Call the neurointervention team now.
- Give IV thrombolysis first if eligible. Neither treatment should delay the other.
- BP: keep below 185/110 mmHg before the procedure. After successful recanalisation, a target SBP below 140 mmHg is harmful unless another condition needs it.
- A large core (low ASPECTS or large CTP core) does not by itself exclude thrombectomy. Decide with the stroke team.
- Weigh pre-stroke function, frailty, comorbidities and the patient's wishes.
- Beyond 24 h: consider only if imaging shows salvageable brain (consensus advice only).
11Action No LVO, or after thrombectomy: stroke unit care
After thrombolysis: no antiplatelet or anticoagulant for 24 h and until repeat imaging excludes haemorrhage. Thrombectomy without thrombolysis, or no reperfusion treatment: start antiplatelet once imaging excludes haemorrhage. Stent placed: antiplatelet timing per the neurointerventionist.
- Neurological deterioration: urgent clinical review and repeat CT.
- Swallow screen before any oral food, fluid or medicine.
- Repeat CT or MRI about 24 h after thrombolysis or thrombectomy.
- Atrial fibrillation: the stroke team sets the anticoagulant start time by infarct size and imaging.
12End Continue stroke unit care
Rehabilitation and secondary prevention follow the stroke unit pathways.
If No- Path rejoins step 11Shared downstream outcome
- 4.5-24 h or wake-up
13Action 4.5 to 24 h or wake-up stroke: CTP or MRI to select treatment
4.5-9 h (or from mid-point of sleep) with CTP mismatch: IV alteplase 0.9 mg/kg (max 90 mg) may be given, unless immediate thrombectomy is planned.
- Unknown onset with MRI DWI-FLAIR mismatch: alteplase 0.9 mg/kg (max 90 mg) may be given within 4.5 h of symptom recognition.
- Same disabling-deficit rule, contraindications, coagulation limits and BP limit as the within-4.5 h step.
- Beyond 9 h: thrombolysis only on stroke specialist advice (for example LVO when thrombectomy is not available in time). Assess for thrombectomy.
- Path rejoins step 08Shared downstream outcome
- More than 24 h
14Action More than 24 h: no thrombolysis; CTA and CTP if deficit is disabling
Thrombectomy may still be considered if imaging shows salvageable brain (consensus advice only). Decide with the stroke team.
- Path rejoins step 08Shared downstream outcome
Guideline Source
2026 AHA/ASA Guideline for the Early Management of Patients With Acute Ischemic Stroke; Australian and New Zealand Living Clinical Guidelines for Stroke Management (Chapters 2 and 3)
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Adults only. Children need a paediatric stroke pathway.
- Thrombectomy beyond 24 h rests on consensus advice only; selection beyond 6 h and for a large core varies by centre. Decide with the stroke team.
- CTP and MRI mismatch criteria vary by institution.
Contraindicated Populations
Children under 18 years (use a paediatric stroke pathway)
Applicable Regions
USAUUKEU
AU: Follows the Australian and New Zealand Living Clinical Guidelines for Stroke Management. METALYSE 25 mg (tenecteplase) is registered for acute ischaemic stroke within 4.5 h.
EU: ESO guidelines apply.
UK: NICE NG128 (stroke and TIA in over 16s) applies.
US: AHA/ASA 2026 acute ischaemic stroke guideline. AHA keeps BP below 180/105 mmHg after thrombolysis.
Version 2Next review: 2027-09-30
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Related Resources
Frequently Asked Questions
What is the Acute Stroke Imaging Protocol (AHA/ASA)?
The Acute Stroke Imaging Protocol (AHA/ASA) is a diagnostic clinical algorithm for Radiology. It provides a structured decision tree to guide clinical decision-making, based on 2026 AHA/ASA Guideline for the Early Management of Patients With Acute Ischemic Stroke; Australian and New Zealand Living Clinical Guidelines for Stroke Management (Chapters 2 and 3).
What guideline is the Acute Stroke Imaging Protocol (AHA/ASA) based on?
This algorithm is based on 2026 AHA/ASA Guideline for the Early Management of Patients With Acute Ischemic Stroke; Australian and New Zealand Living Clinical Guidelines for Stroke Management (Chapters 2 and 3) (DOI: 10.1161/STR.0000000000000513).
What are the limitations of the Acute Stroke Imaging Protocol (AHA/ASA)?
Known limitations include: Adults only. Children need a paediatric stroke pathway.; Thrombectomy beyond 24 h rests on consensus advice only; selection beyond 6 h and for a large core varies by centre. Decide with the stroke team.; CTP and MRI mismatch criteria vary by institution.. Individual patient factors may require deviation from these recommendations.
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