What is the preferred imaging modality, Non-Contrast Computed Tomography (CT) versus Contrast Computed Tomography (CT), for initial acute stroke workup?

From the Guidelines

Non-Contrast Computed Tomography (CT) is the preferred initial imaging modality for acute stroke workup.

Key Points

• The primary goal of initial imaging in acute stroke is to exclude hemorrhage and identify early infarct signs, which can be achieved with non-contrast CT 1.
• Non-contrast CT is widely available, quick, and sensitive for detecting intracranial hemorrhage, making it the ideal initial imaging modality 1.
• Contrast CT may be considered later in the workup, particularly if CT angiography (CTA) or CT perfusion (CTP) is needed to guide hyperacute care, but it should not delay initial treatment with tPA thrombolysis or endovascular therapy 1.
• The use of contrast infusion in initial imaging is not necessary unless required for CTA or CTP, or if there is a concern about a brain tumor or infectious process 1.
• Recent guidelines and studies support the use of non-contrast CT as the initial imaging modality, with vascular imaging, such as CTA, considered later in the workup if necessary 1.

Imaging Modalities

• Non-contrast CT: initial imaging modality of choice for acute stroke workup
• Contrast CT: may be considered later in the workup for CTA or CTP
• CT angiography (CTA): may be considered to guide hyperacute care, particularly if there is a high suspicion of large vessel occlusion (LVO) 1
• CT perfusion (CTP): may be considered to assess cerebral blood flow and guide hyperacute care 1

From the Research

Imaging Modalities for Acute Stroke Workup

The preferred imaging modality for initial acute stroke workup is a topic of ongoing research and debate.

• Non-Contrast Computed Tomography (CT) is traditionally used in the initial assessment of acute ischemic stroke patients to exclude hemorrhage or alternative pathology 2, 3.
• However, recent studies suggest that Contrast Computed Tomography (CT) with CT Perfusion (CTP) imaging may provide additional benefits in guiding treatment decisions, such as endovascular mechanical thrombectomy (MT) and intravenous thrombolysis (IVT) 2, 4.
• Virtual Non-Contrast CT (VNCCT) reconstructed from intravenous contrast-enhanced dual-energy CT (iv-DECT) has also been shown to be a feasible alternative to non-contrast CT in patients with suspected acute cerebral ischemia, with similar diagnostic performance 5.
• The reliability of visual assessment of non-contrast CT, CT angiography source images, and CT perfusion in patients with suspected ischemic stroke has been evaluated, with CT perfusion showing excellent inter- and intra-observer agreement 4.

Comparison of Imaging Modalities

• Non-contrast CT is widely available and rapid, making it an ideal initial imaging tool for evaluating stroke 3.
• CT angiography (CTA) is commonly used as a follow-up study to identify intracranial large vessel occlusions and cervical carotid or vertebral artery disease 3.
• CT perfusion is widely used in endovascular therapy trials and provides valuable information on tissue viability and fate in acute stroke 2, 3, 4.
• Magnetic Resonance Imaging (MRI) and Magnetic Resonance Angiography (MRA) can provide additional insights into stroke etiology and outcomes prognostication 3.
• Advanced stroke imaging techniques, such as CT and MR angiography and perfusion imaging, are increasingly being used in acute stroke settings 6.