What is the appropriate timeframe for a Computed Tomography (CT) scan in acute stroke diagnosis?

From the Guidelines

The appropriate timeframe for a Computed Tomography (CT) scan in acute stroke diagnosis is within 20 minutes of arrival in the emergency department (ED) for at least 50% of patients who may be candidates for IV alteplase and/or mechanical thrombectomy 1.

Key Points

• Brain imaging should be performed on all patients admitted to hospital with suspected acute stroke on arrival to hospital, with noncontrast CT (NCCT) being the preferred initial imaging modality 1.
• The door-to-imaging time should be reduced to minimize delays in treatment, with a goal of completing the CT scan within 25 minutes of the patient's arrival in the ED 1.
• Interpretation of CT scans should be done promptly by a physician with expertise in reading CT and MRI studies of the brain parenchyma, ideally within 45 minutes of patient arrival in the ED 1.
• Advanced imaging, such as CT perfusion or MRI, may be considered for patient selection for acute reperfusion therapy beyond the time windows for intravenous fibrinolysis, but should not delay treatment 1.

Important Considerations

• The benefit of IV alteplase and mechanical thrombectomy is time-dependent, with earlier treatment leading to bigger proportional benefits 1.
• CT hyperdense MCA sign and CT hypoattenuation should not be used as criteria to withhold IV alteplase from patients who otherwise qualify 1.

From the Research

Timeframe for CT Scan in Acute Stroke Diagnosis

The appropriate timeframe for a Computed Tomography (CT) scan in acute stroke diagnosis is crucial for effective treatment. According to the studies, the following timeframes are relevant:

• The therapeutic window for acute stroke treatment can extend up to 4.5 hours after stroke onset for intravenous tissue plasminogen activator treatment, and up to 24 hours for endovascular thrombectomy (EVT) 2.
• The median duration of a CT scan is around 9 minutes, which is shorter than the median duration of an MRI scan (13 minutes) 3.
• The stroke-onset-to-imaging time, onset-to-intravenous tPA time, and onset-to-angiography-suite time do not differ significantly between CT and MRI groups, indicating that CT can be performed within a similar timeframe to MRI without delaying treatment or impacting functional outcome 3.
• CT angiography (CTA) and xenon-enhanced CT cerebral blood flow (XeCT CBF) can be used in conjunction with CT to distinguish subgroups of acute ischemic stroke victims and predict the subgroups most likely to benefit from thrombolytic therapy, with a timeframe of up to 24 hours after stroke symptom onset 4.

Key Considerations

• The choice of imaging modality (CT or MRI) does not significantly impact functional outcome in acute ischemic stroke patients 3.
• CT-based assessment, including CT, CTA, and XeCT CBF, can provide valuable information for selecting patients for acute-stroke treatment and predicting outcome 4.
• The use of CT techniques, such as angio-CT and perfusion CT, can help improve patient triage and selection of the most adequate treatment, leading to further improvements in clinical outcomes 5.