Which imaging modality is commonly used to visualize collateral networks in Moyamoya disease?

• A. MR angiography
• B. MRI without contrast
• C. Plain CT
• D. Ultrasound

Answer: (A)

The key concept is that Moyamoya disease creates a distinctive network of collateral cerebral vessels that are best seen with vascular imaging. MR angiography is commonly used because it visualizes the cerebral arteries and the abnormal Moyamoya collateral vessels clearly, often noninvasively and without radiation. Time-of-flight or other MR angiography methods can reveal both the focal narrowing of the intracranial arteries and the dense, smokelike collateral networks that develop in response. In children, noncontrast MR angiography is especially useful to minimize contrast exposure while still providing detailed vascular maps. In contrast, MRI performed without contrast highlights brain tissue rather than vessels, plain CT offers limited detail of intracranial vasculature, and ultrasound cannot reliably image deep intracranial collateral networks. While catheter angiography provides definitive vascular detail, MR angiography remains the practical, commonly used option for visualizing Moyamoya collaterals.