Can a Magnetic Resonance Angiography (MRA) of the carotids and a Magnetic Resonance Imaging (MRI) of the brain be performed at the same time?

Combined MRI Brain and MRA Carotids: Technical Feasibility and Clinical Practice

Yes, MRI of the brain and MRA of the carotid arteries can absolutely be performed during the same imaging session, and this combined approach is explicitly recommended in current ACR guidelines for multiple clinical scenarios including stroke evaluation, TIA workup, and cranial neuropathy assessment. 1

Standard Combined Imaging Protocols

The American College of Radiology specifically endorses "MRA head and neck" as a single combined examination with appropriateness ratings of 8 out of 9 (usually appropriate) for:

• TIA evaluation: Combined MRI brain with MRA head and neck receives the highest appropriateness rating, allowing simultaneous assessment of brain parenchyma and vascular anatomy 1
• Acute stroke workup: MRI brain can be obtained in conjunction with MRA head and neck, with preferred protocols including noncontrast head MRA and contrast-enhanced neck MRA 1
• Cranial neuropathy: MRA may be complementary to MRI to characterize vasculature when evaluating brainstem syndromes or suspected carotid dissection 1

Technical Implementation

The combined examination is performed as a single continuous session without repositioning the patient:

• Time efficiency: A standardized multimodal MRI protocol including brain imaging and MRA can be completed in approximately 10 minutes, making it highly practical for clinical use 2
• Simultaneous coverage: The examination provides noninvasive noncontrast imaging of cervical and cerebral vasculature along with brain parenchyma in one session 3
• Protocol flexibility: Institutions can combine MRI head with MRA head and neck without or with IV contrast depending on clinical indication 1

Contrast Administration Strategy

The preferred approach for combined imaging uses noncontrast MRA of the head (time-of-flight technique) with contrast-enhanced MRA of the neck:

• Head MRA: Time-of-flight technique without contrast effectively assesses intracranial vasculature for stenosis or occlusion 2
• Neck MRA: Contrast-enhanced technique provides superior visualization of carotid bifurcation and extracranial vessels 1
• Brain MRI: Can be performed without contrast for most stroke and ischemic evaluations, as acute and chronic ischemic changes are depicted without IV contrast 2

Clinical Advantages of Combined Imaging

Performing both studies together offers multiple benefits:

• Comprehensive evaluation: Allows assessment of both the brain parenchyma for infarction/hemorrhage and the vascular supply for stenosis, occlusion, or dissection in a single session 1, 3
• Ischemic complication detection: MRI/MRA provides additional characterization of ischemic complications compared to CTA, particularly valuable in dissection cases 1
• Workflow efficiency: Conducting all relevant studies in as few sessions as possible avoids treatment delays, which is critical in acute stroke management 2

Diagnostic Accuracy

The combined MRI/MRA approach demonstrates excellent diagnostic performance:

• Stenosis detection: MRA shows sensitivity of 100% and specificity of 96% for detecting >50% internal carotid artery stenosis, with 100% sensitivity and 77% specificity for >75% stenosis 4
• Correlation with angiography: MRA demonstrates 86% agreement with contrast angiography for internal carotid artery assessment 3
• Surgical concordance: Degree of stenosis detected by MRA is concordant with surgical findings in 98% of patients (39 of 40) 3

Common Pitfalls to Avoid

Critical errors that compromise patient outcomes:

• Delaying treatment for imaging: If a patient is within the 4.5-hour window for acute stroke and has no contraindications on initial imaging, IV tPA should be initiated without waiting for additional vascular imaging 2
• Assuming single modality sufficiency: Do not assume normal CT excludes the need for MRI/MRA; studies show MRI detects additional findings in up to 27% of patients with normal CT 5
• Overreliance on MRA alone: While MRA is highly accurate, it tends to overestimate stenosis severity compared to conventional angiography, particularly at the carotid bifurcation 6, 7

When Combined Imaging is Most Appropriate

Specific clinical scenarios where combined MRI brain and MRA carotids should be ordered together:

• Suspected carotid dissection with cranial nerve palsies: MRA evaluates for dissection while MRI assesses brainstem and ischemic complications 1
• TIA with unknown etiology: Combined imaging identifies both parenchymal changes and vascular stenosis/occlusion in a single session 1
• Brainstem syndromes: Most are due to infarction/hemorrhage, requiring both parenchymal assessment and vascular characterization 1