What is the most appropriate initial CT scan to order for a patient presenting with intermittent headaches, radiation to the left eye, and transient visual changes: CTA, CT venogram, or CT head and brain?

From the Guidelines

For a patient presenting with intermittent headaches, radiation to the left eye, and transient visual changes, a CTA (CT angiography) of the head and neck is the most appropriate initial imaging study. This recommendation is based on the high sensitivity and specificity of CTA in diagnosing vascular pathology, including arterial injury, as reported in a prospective study of 146 trauma patients who received both catheter angiography and CTA, with a sensitivity of 97.7% and a specificity of 100% for the diagnosis of vascular injury 1. The patient's symptoms, such as radiation of pain to the left eye and transient visual changes, suggest possible vascular pathology, and CTA is the most useful initial imaging evaluation for suspected intracranial arterial injury.

The Biffl grading scale for arterial injury, which has been shown to be reliable for CTA, can help guide management, with medical therapy with antiplatelet or anticoagulation potentially appropriate for lower grades of arterial injury, and endovascular or surgical treatment more likely required for higher grades 1. While a non-contrast CT head and brain can provide a rapid assessment of potential intracranial pathologies, the patient's symptoms suggest a higher likelihood of vascular pathology, making CTA a more targeted and appropriate initial imaging study.

Key points to consider when ordering a CTA include:

• The use of modern CT equipment, which has been shown to have comparable accuracy to catheter angiography 1
• The development of >8-slice multidetector-row CT, which has allowed CTA to become the standard in diagnosis of suspected cerebrovascular injury 1
• The potential for CTA to guide management, with different treatment approaches depending on the grade of arterial injury 1

In contrast, a CT venogram would be more specifically indicated if venous sinus thrombosis is suspected, which typically presents with different symptoms. A non-contrast CT head and brain may be considered if there is a high suspicion of other intracranial pathologies, such as hemorrhage or mass lesions, but the patient's symptoms suggest a higher likelihood of vascular pathology, making CTA a more appropriate initial imaging study.

From the Research

Initial Evaluation

The patient presents with a two-week history of intermittent headaches, radiation to the left eye, and transient visual changes. Given the symptoms, a thorough evaluation is necessary to determine the underlying cause.

Imaging Options

The following imaging options are considered:

• CTA (Computed Tomography Angiography)
• CT venogram
• CT head and brain

Considerations for Each Option

• CTA: Studies have shown that CTA can be useful in evaluating patients with acute severe headache, normal neurological examination, and normal noncontrast head computed tomography (NCCT) 2, 3. CTA can help identify vascular abnormalities such as aneurysms, cerebral venous thrombosis (CVT), and reversible cerebral vasoconstriction syndrome (RCVS).
• CT venogram: CT venography is a suitable noninvasive method to study cerebral veins and can be used to diagnose sinus thrombosis 4, 5. It is superior to conventional CT and can provide detailed information about flow and anatomy of cerebral veins.
• CT head and brain: A noncontrast CT head and brain is typically the initial imaging modality for evaluating headaches, but it may not provide sufficient information to diagnose certain conditions such as CVT or RCVS.

Recommendation

Based on the patient's symptoms and the available evidence, a CTA or CT venogram may be considered as the initial imaging modality. However, if there is a high suspicion of cerebral venous thrombosis, a CT venogram may be more appropriate 6, 5. It is essential to consider the patient's clinical presentation and medical history when selecting the most suitable imaging option.

Key Points to Consider

• The patient's symptoms, such as radiation to the left eye and transient visual changes, suggest a possible vascular cause.
• CTA and CT venogram can provide valuable information about vascular abnormalities, but the choice of imaging modality depends on the suspected underlying condition.
• A thorough evaluation, including a detailed medical history and physical examination, is necessary to determine the most appropriate imaging strategy.