Transient ischaemic attack

Population Covered By The Guidance

This pathway provides guidance on the imaging adult patients with a history of suspected transient ischaemic attack.

Lead Researcher: Bridget Copson, Richard Mendelson

Experts & Contributors: Con Phatourous

Date reviewed: August 2023

Date Published: July 2025

Image 1a and 1b (Carotid Doppler): Moderate amount of plaque at the origin of the left common carotid artery (arrow) extending into the internal carotid artery. Velocity measurements indicate stenosis in the order of 70%.

Left Common and Internal Carotid Artery Stenosis

Image 2 (MR Angiography): Narrowing of the left middle cerebral artery with reduced flow (arrow).

Left Middle Cerebral Artery Stenosis

Left Internal Carotid Artery Stenosis

Worldwide, there is heterogeneity in the approach to imaging of TIA
Multiple international guidelines note the importance of clinical evaluation in a TIA clinic where available.
There is overall agreement between international guidelines that carotid imaging (and neuroimaging if performed) should be completed in the acute setting to triage patients who may require early management (suggested within 24 hours)
Carotid imaging (with CT angiogram or doppler ultrasound) should be performed to assess for extracranial arterial stenosis or vulnerable plaque.
If there is a stenosis > 50% or evidence of vulnerable plaque on doppler ultrasound, a second imaging modality is recommended.
While non-stenotic carotid plaque can be a cause for TIA, if there is no significant extracranial stenosis (<50%), further tests to investigate for an alternative cause for emboli should be considered (Echocardiogram/Holter).
If there is a stenosis > 50%, referral for consideration of carotid intervention is recommended.

Date of literature search:

September 2023 References are graded from Level I to V according to the Oxford Centre for Evidence-Based Medicine, Levels of Evidence. Download the document

Fonseca AC, Merwick A, Dennis M, Ferrari J, Ferro JM, Kelly P, et al. European Stroke Organisation (ESO) guidelines on management of transient ischaemic attack. European Stroke Journal. 2021;6(2):CLXIII-CLXXXVI. (Guideline)
Linden B. National Institute for Health and Care Excellence NG128 stroke and transient ischaemic attack in over 16s: diagnosis and initial management. British Journal of Cardiac Nursing. 2020;15(9):1-5. (Guideline)
Gladstone DJ, Lindsay MP, Douketis J, Smith EE, Dowlatshahi D, Wein T, et al. Canadian stroke best practice recommendations: secondary prevention of stroke update 2020. Canadian Journal of Neurological Sciences. 2022;49(3):315-37. (Guideline)
Kleindorfer DO, Towfighi A, Chaturvedi S, Cockroft KM, Gutierrez J, Lombardi-Hill D, et al. 2021 guideline for the prevention of stroke in patients with stroke and transient ischemic attack: a guideline from the American Heart Association/American Stroke Association. Stroke. 2021;52(7):e364-e467. (Guideline)
Whiteley WN, MacRaild A, Wang Y, Dennis M, Al-Shahi Salman R, Gray A, et al. Clinical Diagnosis and Magnetic Resonance Imaging in Patients With Transient and Minor Neurological Symptoms: A Prospective Cohort Study. Stroke. 2022;53(11):3419-28. (Level II Evidence)
Amarenco P, Lavallée PC, Labreuche J, Albers GW, Bornstein NM, Canhão P, Caplan LR, Donnan GA, Ferro JM, Hennerici MG, Molina C. One-year risk of stroke after transient ischemic attack or minor stroke. New England Journal of Medicine. 2016 Apr 21;374(16):1533-42. (Level II Evidence)
Coutts SB, Modi J, Patel SK, Aram H, Demchuk AM, Goyal M, et al. What causes disability after transient ischemic attack and minor stroke? Results from the CT and MRI in the Triage of TIA and minor Cerebrovascular Events to Identify High Risk Patients (CATCH) Study. Stroke. 2012;43(11):3018-22. (Level II evidence)
Health NIf, Excellence C. Stroke and transient ischaemic attack in over 16s: diagnosis and initial management: National Institute for Health and Care Excellence; 2019. (Guideline)
Wasserman JK, Perry JJ, Sivilotti ML, Sutherland J, Worster A, Émond M, et al. Computed tomography identifies patients at high risk for stroke after transient ischemic attack/nondisabling stroke: prospective, multicenter cohort study. Stroke. 2015;46(1):114-9. (Level II evidence)
Hurford R, Li L, Lovett N, Kubiak M, Kuker W, Rothwell PM. Prognostic value of “tissue-based” definitions of TIA and minor stroke: population-based study. Neurology. 2019;92(21):e2455-e61. (Level II evidence)
Amarenco P. Transient ischemic attack. New England Journal of Medicine. 2020;382(20):1933-41. (Level II Evidence)
Cassola N, Baptista-Silva JC, Nakano LC, Flumignan CD, Sesso R, Vasconcelos V, et al. Duplex ultrasound for diagnosing symptomatic carotid stenosis in the extracranial segments. Cochrane Database of Systematic Reviews. 2022(7). (Level 1 Evidence)
Yu A, Coutts S. Role of brain and vessel imaging for the evaluation of transient ischemic attack and minor stroke. Stroke. 2018;49(7):1791-5. (Level II Evidence)
Forjoe T, Asad Rahi M. Systematic review of preoperative carotid duplex ultrasound compared with computed tomography carotid angiography for carotid endarterectomy. The Annals of The Royal College of Surgeons of England. 2019;101(3):141-9. (Level 1 Evidence)
Mathiesen EB, Bønaa KH, Joakimsen O. Echolucent plaques are associated with high risk of ischemic cerebrovascular events in carotid stenosis: the Tromsø study. Circulation. 2001;103(17):2171-5. (Level III Evidence)
Iannuzzi A, Rubba P, Gentile M, Mallardo V, Calcaterra I, Bresciani A, et al. Carotid atherosclerosis, ultrasound and lipoproteins. Biomedicines. 2021;9(5):521. (Level III Evidence)
Weale AR, Urriza-Rodriguez D. Imaging in vascular disease. Surgery (Oxford). 2015;33(7):308-14. (Level III Evidence)
Naylor A, Ricco J-B, De Borst G, Debus S, De Haro J, Halliday A, et al. Editor's choice–management of atherosclerotic carotid and vertebral artery disease: 2017 clinical practice guidelines of the European Society for Vascular Surgery (ESVS). European Journal of Vascular and Endovascular Surgery. 2018;55(1):3-81. (Guideline)
Netuka D, Belšán T, Broulíková K, Mandys V, Charvát F, Malík J, et al. Detection of carotid artery stenosis using histological specimens: a comparison of CT angiography, magnetic resonance angiography, digital subtraction angiography and Doppler ultrasonography. Acta neurochirurgica. 2016;158:1505-14. (Level II Evidence)
Poisson SN, Nguyen-Huynh MN, Johnston SC, Furie KL, Lev MH, Smith WS. Intracranial large vessel occlusion as a predictor of decline in functional status after transient ischemic attack. Stroke. 2011;42(1):44-7. (Level II Evidence)
Saam T, Hetterich H, Hoffmann V, Yuan C, Dichgans M, Poppert H, et al. Meta-analysis and systematic review of the predictive value of carotid plaque hemorrhage on cerebrovascular events by magnetic resonance imaging. Journal of the American College of Cardiology. 2013;62(12):1081-91. (Level I Evidence)
Gupta A, Baradaran H, Schweitzer AD, Kamel H, Pandya A, Delgado D, et al. Carotid plaque MRI and stroke risk: a systematic review and meta-analysis. Stroke. 2013;44(11):3071-7. (Level I Evidence)
Wardlaw J, Chappell F, Stevenson M, De Nigris E, Thomas S, Gillard J, et al. Accurate, practical and cost-effective assessment of carotid stenosis in the UK. Health Technology Assessment (Winchester, England). 2006;10(30):iii-iv, ix. (Level II Evidence)

Pathway User Guide

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The relative radiation level (RRL) of each imaging investigation is displayed in the pop up box.

SYMBOL	RRL	EFFECTIVE DOSE RANGE
	None	0
	Minimal	< 1 millisieverts
	Low	1-5 mSv
	Medium	5-10 mSv
	High	>10 mSv

Disclaimer

Status Of Recommendations Each pathway is designed to assist clinicians in situations when faced with a large array of possible diagnostic tests and examinations. However, it is recognised that diagnostic practice may differ from a particular pathway depending on local availability of equipment and expertise, as well as the experience of individual clinicians. Therefore each pathway is neither a rigid set of rules, nor a substitute for clinical assessment, and individual patient circumstances should always be considered.

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Panning

CT angiography and MR angiography should include head and neck and image the carotid arteries and Circle of Willis (CoW)

Choices for initial imaging include:
- Carotid Doppler ultrasound
- CT/CT angiography (CTA)
- MR/MR angiography (MRA)
Each modality has its strengths and weaknesses:
- CTA (within 3 days of ictus) is generally regarded as the gold standard,
- However, MR with DWI +/- SWI are very useful adjuncts (see below)
- Non-stenotic plaques (< 50%) may still be the cause of the TIA and medical treatment is recommended .
Carotid Doppler US
- Advantages of US include:
  - Collated diagnostic accuracy in a systematic review by Cochrane of duplex ultrasound compared to the gold standard of digital subtraction angiography was high with > 50% stenosis having a summary sensitivity of 0.91 and a summary specificity of 0.70, for >70% stenosis this improved to a summary sensitivity of 0.85 and specificity of 0.98. Summary sensitivity for occlusion was 0.91 and specificity was 0.95
  - Other studies compared CT angiogram (CTA) with ultrasound, and found with the inclusion of end diastolic volume and peak systolic velocity that the sensitivity and specificity of ultrasound was superior to CT angiogram for >70% stenosis (98.7% and 94.1% respectively compared to 90.6 and 93%)
  - Plaque echogenicity,
  - Increased intimal thickness,
  - Neovascularisation and stiffness .
  - Hypoechoic plaques have an increased risk of cerebrovascular event independent of degree of stenosis .
- Disadvantages of Doppler US include:
CTA/MRA
- CT angiography and MR angiography should include the head and neck, and image the carotid arteries and Circle of Willis (CoW)
- Given there remain limitations of ultrasound, and if a stenosis > 50% is identified, CTA or MR angiogram (MRA) is recommended for confirmation
- CTA/MRA has benefit of intracranial vascular assessment which provides further prognostication for future vascular events
- MRA has the advantage of assessing for intra-plaque haemorrhage, the presence of which is associated with high risk for cerebrovascular events .
- MRA has 92% specificity and ~ 75% sensitivity for detection of severe internal carotid artery stenosis
- MRI protocol may include DWI and SWI (Susceptibility Weighted Imaging).
- For any TIA lasting longer than 1 hour there is a 50% chance of detecting DWI hits on DWI.
- SWI gives information on pial haemosiderosis and cerebral amyloid angiopathy can present with TIA symptoms.
- DWI is useful as an abnormality identifies the vascular territory of the TIA or if multiple territories are invovled. Occasionally posterior circulation TIAs can mimic clinically an anterior circulation TIA.
- MRA has a lower resolution than CTA, is more prone to movement artifact and any stenosis over 70% can result in a flow gap and thus is prone to over-estimation
- CTA may be limited by heavily calcified plaques

Transient ischaemic attack

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