When should I order a computed tomography angiography (CTA)?

From the Guidelines

A computed tomography angiography (CTA) should be ordered in the presence of one or more of the following findings in a severe limb trauma patient: externalised bleeding of arterial origin, vicinity of the injury site to a main vascular axis, presence of a non-expanding haematoma, isolated neurological deficit, or an ankle-brachial index (ABI) less than 0.9, as recommended by the latest guidelines 1. When evaluating the need for a CTA, it is essential to consider the clinical presentation and the potential benefits of detailed vascular imaging. The following scenarios may warrant a CTA:

• Suspected vascular injury in a severe limb trauma patient, as identified by the presence of externalised bleeding, proximity to a main vascular axis, non-expanding haematoma, isolated neurological deficit, or ABI less than 0.9 1
• Evaluation of vascular conditions such as pulmonary embolism, aortic dissection, aneurysms, arterial stenosis, or vascular malformations
• Planning for vascular interventions, such as revascularization procedures
• Emergency situations like acute chest pain with suspected aortic pathology or stroke evaluation within the treatment window The test involves intravenous contrast administration, so patients with significant kidney dysfunction (GFR <30 mL/min) or contrast allergies may require alternative imaging or premedication protocols 1. Some key points to consider when ordering a CTA include:
• The use of CTA as the first-line radiological examination for the exploration of limb vessels in severe trauma patients, due to its high sensitivity and specificity 1
• The importance of adequate hydration before and after the procedure, particularly in patients with kidney concerns
• The potential use of N-acetylcysteine for kidney protection in patients with significant kidney dysfunction
• The value of CTA in providing excellent anatomical detail of vessels, making it superior to non-contrast CT for vascular pathology 1 In patients with lower extremity peripheral artery disease, CTA can be useful for assessment of anatomy and severity of disease, and to determine potential revascularization strategy, as recommended by the 2024 ACC/AHA/AACVPR/APMA/ABC/SCAI/SVM/SVN/SVS/SIR/VESS guideline 1.

From the Research

Computed Tomography Angiography (CTA) Ordering Guidelines

When considering ordering a computed tomography angiography (CTA), several factors come into play, particularly in the context of stroke and transient ischemic attack (TIA). The decision to order a CTA should be based on the clinical presentation and the need for rapid diagnosis and treatment of vascular lesions.

Indications for CTA

• In cases of suspected stroke, particularly ischemic or hemorrhagic, CTA can be useful in identifying relevant vascular lesions 2.
• For patients with transient ischemic attacks (TIAs) or minor ischemic strokes, CTA can help in decision-making regarding further treatment, such as carotid endarterectomy 3.
• CTA is also indicated in patients with a high-risk profile, those with a high prior probability of carotid artery stenosis, or when surgery can be performed without delay 3.
• In the setting of acute stroke, upfront vascular imaging with CTA can impact thrombectomy transfer time and is recommended for all suspected ischemic stroke patients presenting within 24 hours of symptom onset 4.

Timing of CTA

• Early assessment of the intracranial and extracranial vasculature using CTA can predict recurrent stroke and clinical outcome in patients with TIA and minor stroke 5.
• The timing of CTA should be as soon as possible after the onset of symptoms, with studies showing that early CTA can reduce door-to-CTA start and door-to-CTA result times 4.

Comparison with Other Imaging Modalities

• The use of CTA compared to other imaging modalities, such as non-contrast computed tomography (NCCT) or magnetic resonance angiography (MRA), does not significantly reduce recurrent stroke, mortality, or disability in ischemic stroke and TIA patients 6.
• However, CTA can provide valuable information on vascular lesions and guide further management, making it a useful tool in the diagnostic workup of stroke and TIA patients 2, 3, 5.