Added Value of Stroke Protocol MRI Following Negative Initial CT in the Acute Stroke Setting

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Computed Tomography (CT) is the primary imaging modality for acute stroke.
• A significant number of acute stroke cases present with a normal initial CT scan.
• Further diagnostic imaging is often required when CT is inconclusive.

Purpose of the Study:

• To evaluate the diagnostic utility of stroke protocol Magnetic Resonance Imaging (MRI) after a negative initial CT brain scan.
• To quantify the added value of MRI in diagnosing acute stroke when CT results are normal.
• To assess the rate of positive MRI findings in patients with clinical stroke syndromes and negative CT scans.

Main Methods:

• Retrospective analysis of patients within a tertiary referral stroke center over six months.
• Inclusion criteria: clinical stroke syndrome, negative initial CT brain, and subsequent diffusion-weighted MRI.
• Review of stroke and radiology databases to identify eligible patients.

Main Results:

• Out of 92 reviewed patients, 73 met the inclusion criteria (39 male, 34 female, mean age 62.1 years).
• Twenty MRI studies (27.4%) revealed acute or subacute ischemia despite a normal initial CT.
• The average time between CT and MRI was 4.7 days.

Conclusions:

• While CT remains the first-line investigation for acute stroke, it has limitations in detecting early ischemic changes.
• Stroke protocol MRI demonstrates substantial added diagnostic value in cases with a negative initial CT.
• Utilizing MRI after a negative CT improves the accuracy of stroke diagnosis and detection of ischemic events.