Should a magnetic resonance imaging (MRI) of the brain be obtained approximately 24 hours after onset of a left‑sided ischemic cerebrovascular accident (stroke) when the initial non‑contrast computed tomography (CT) was normal and the patient with compensated Child‑Pugh class A cirrhosis declined thrombolysis and mechanical thrombectomy?

MRI Brain at 24 Hours Post-Stroke: Clinical Utility Despite Declined Intervention

Yes, obtain an MRI brain at 24 hours post-stroke even though the patient declined acute reperfusion therapies, as this imaging serves critical diagnostic, prognostic, and secondary prevention purposes that directly impact subsequent management and outcomes.

Primary Rationale for 24-Hour Follow-Up Imaging

A repeat brain scan at 24 hours after initial stroke event should be performed regardless of clinical stability, as this is a standard recommendation for all stroke patients 1. This timing is specifically chosen because:

• Diagnostic confirmation: About one-quarter of acute stroke cases with initially negative CT will show evidence of acute/subacute infarction on MRI within 1-2 days, which helps confirm the diagnosis and may improve patient education and adherence to prevention regimens 2, 1

• MRI detects 32.5% of acute infarcts missed by initial CT in patients presenting with stroke symptoms, with particular value for posterior circulation strokes where follow-up MRI may be appropriate even when initial imaging is negative 2, 3

• The 24-hour scan is required before starting anticoagulants or antiplatelet agents for secondary stroke prevention, making it essential for safe initiation of preventive therapies 1

Why MRI Over Repeat CT at 24 Hours

MRI is superior to CT for confirming ischemic stroke and characterizing the lesion at this timepoint:

• MRI with diffusion-weighted imaging (DWI) has 77% sensitivity versus only 16% for CT within the first 3 hours, and remains superior for up to 12 hours and beyond 4, 5

• MRI provides additional diagnostic information including lesion pattern that can provide clues to underlying etiology in 13.7% of cases, which is critical for tailoring secondary prevention strategies 3

• MRI is more accurate for detecting chronic hemorrhage and small intraventricular hemorrhages, which may influence anticoagulation decisions 1

Specific Clinical Value in This Patient

Despite the declined acute interventions, the 24-hour MRI serves multiple critical purposes:

1. Hemorrhagic Transformation Surveillance

• Patients with cirrhosis have altered hemostasis and increased bleeding risk
• Excluding hemorrhagic conversion is essential before initiating antiplatelet or anticoagulation therapy for secondary prevention 1
• This is particularly important given the patient's cirrhosis, even if compensated

2. Stroke Mechanism Identification

• MRI can identify intracranial atherosclerotic disease, which supports treatment to aggressive antiatherosclerotic targets and often indicates need for dual antiplatelet therapy 2
• Lesion pattern on DWI can suggest cardioembolic versus small vessel versus large vessel etiology, fundamentally changing secondary prevention strategy 3

3. Prognostication and Rehabilitation Planning

• Confirming diagnosis and extent of infarction helps with patient education and prognostication, which promotes adherence to prescribed prevention regimens 2, 1
• Final infarct volume guides rehabilitation intensity and discharge planning

Recommended MRI Protocol

Order MRI brain without contrast including the following sequences 4:

• DWI: Most sensitive for acute infarction (91% sensitivity, 95% specificity within 6 hours) 4
• FLAIR: Detects 91% of ischemic lesions and assesses chronicity 4
• Gradient-echo (GRE) or susceptibility-weighted imaging (SWI): Excludes hemorrhagic transformation with superior sensitivity compared to CT 4
• MRA head and neck (time-of-flight, no contrast needed): Identifies large vessel stenosis/occlusion to guide secondary prevention 4

Contrast is not indicated for routine stroke follow-up imaging, as acute and chronic ischemic changes are depicted without IV contrast 4

Critical Caveat Regarding Cirrhosis

The patient's early cirrhosis (Child-Pugh A) is not a contraindication to MRI, but consider:

• Gadolinium contrast should be avoided if there is any concern for renal dysfunction (risk of nephrogenic systemic fibrosis), though the recommended protocol above does not require contrast 4
• The cirrhosis itself was the stated reason for declining thrombolysis, but this does not negate the value of diagnostic imaging for secondary prevention

Common Pitfall to Avoid

Do not assume that declining acute intervention eliminates the need for follow-up imaging. The 24-hour scan serves entirely different purposes:

• Acute intervention (declined) = treating the current stroke
• 24-hour imaging = confirming diagnosis, excluding complications, and enabling safe secondary prevention to prevent the next stroke

The patient still requires aggressive secondary stroke prevention, and the MRI findings will directly guide antiplatelet selection, anticoagulation decisions (if cardioembolic source identified), statin intensity, and blood pressure targets 2, 1.