Can focal cerebral arteriopathy present with negative Magnetic Resonance Angiography (MRA) findings?

Focal Cerebral Arteriopathy Can Present with Negative MRA Findings

Yes, focal cerebral arteriopathy (FCA) can present with negative Magnetic Resonance Angiography (MRA) findings, necessitating further diagnostic evaluation with catheter angiography when clinical suspicion remains high. 1

Understanding Focal Cerebral Arteriopathy and MRA Limitations

Focal cerebral arteriopathy is characterized by unilateral intracranial arteriopathy involving the distal internal carotid artery and proximal segments of the middle and anterior cerebral arteries. Its detection through imaging is crucial for appropriate management:

• MRA has inherent limitations in detecting certain vascular abnormalities, particularly those involving small vessels or subtle arterial changes 1
• Small-vessel vasculitis, including some forms of FCA, may have vessel abnormalities too small to be demonstrated on MRA 1
• MRA without contrast can diagnose arteriovenous malformations (AVMs) and aberrant internal carotid arteries but has less sensitivity for detecting smaller vascular abnormalities 1

Diagnostic Algorithm When FCA is Suspected

When focal cerebral arteriopathy is suspected but initial MRA is negative:

1. First-line imaging:

   • MRI brain with diffusion-weighted imaging to evaluate for acute infarction 1
   • MRA head (preferably with contrast) for initial vascular assessment 1

2. If MRA is negative but clinical suspicion remains high:

   • Proceed to catheter angiography (conventional cerebral angiogram) 1
   • Catheter angiography is the gold standard and has better sensitivity than MRA 1

3. Follow-up imaging:

   • Serial imaging is essential to differentiate FCA from progressive arteriopathies 2
   • Repeat MRA or catheter angiography in 1-2 weeks if initial studies are negative 1

Why MRA May Miss Focal Cerebral Arteriopathy

Several factors contribute to false-negative MRA results in FCA:

• MRA has limited spatial resolution compared to catheter angiography 1
• Source images of 3-D time-of-flight MRA can detect moderate to high-flow vascular abnormalities but may miss subtle arterial changes 1
• Small-vessel vasculitis (vessel abnormality too small to be demonstrated on MRA) is best diagnosed by brain biopsy when imaging is negative 1
• Early stages of arteriopathy may not yet demonstrate significant luminal changes detectable by MRA 3

Clinical Implications and Management

The diagnosis of FCA has significant implications for patient management:

• Misdiagnosis can lead to inappropriate treatment choices and increased risk of stroke recurrence 3
• FCA can be confused with other conditions such as arterial dissection, moyamoya disease, or vasculitis at initial presentation 3
• In pediatric patients, FCA is one of the most common causes of arterial ischemic stroke and requires accurate diagnosis for appropriate management 4
• Adult patients with FCA typically present with recurrent transient ischemic attacks or minor strokes within a single vascular territory over days to weeks 2

Important Caveats

• When MRA is negative but clinical suspicion for vascular abnormality remains high, catheter angiography should not be delayed 1
• Catheter angiography carries risks, particularly in young children, and should be performed by experienced personnel 1
• The diagnostic accuracy of imaging studies should be considered in the context of the patient's age, clinical presentation, and risk factors 3
• Recent evidence suggests a possible association between viral infections (including COVID-19) and FCA, highlighting the importance of thorough clinical evaluation 4, 5