Should I get a computed tomography (CT) brain scan or magnetic resonance imaging (MRI) after experiencing transient ischemic attack (TIA) symptoms a week ago?

Brain Imaging After TIA One Week Ago: MRI is Preferred

You should get an MRI with diffusion-weighted imaging (DWI) as the preferred imaging modality, though a CT scan is acceptable if MRI is unavailable or contraindicated. 1 Even though you are presenting one week after symptom onset, brain imaging remains important for confirming the diagnosis, identifying the stroke mechanism, and guiding secondary prevention strategies.

Why MRI Over CT at This Time Point

• MRI with DWI is vastly superior to CT for detecting ischemic lesions after TIA, showing 77% sensitivity compared to only 16% for CT within the first few hours 2
• CT misses approximately 95% of acute ischemic lesions in TIA patients - in one study, CT showed no acute pathology in 95.7% of cases, but subsequent MRI revealed acute infarcts in 32.5% of those same patients 3
• Nearly half (48%) of TIA patients have visible ischemic lesions on DWI, even when symptoms have completely resolved 4
• MRI findings can change your diagnosis and treatment plan - diffusion imaging alters the suspected anatomic localization and etiologic mechanism in over one-third of TIA patients 4

Complete Diagnostic Workup You Need

Beyond brain imaging, you require a comprehensive stroke evaluation:

Vascular Imaging (Critical - Don't Skip This)

• CT angiography (CTA) from aortic arch to vertex is the ideal first-line test to assess both extracranial and intracranial circulation 1
• Carotid ultrasound or MR angiography are acceptable alternatives based on availability 1
• This is essential because identifying carotid stenosis >50% requires urgent treatment - the benefit of carotid revascularization diminishes rapidly after 2 weeks 5

Cardiac Evaluation

• 12-lead ECG is mandatory to screen for atrial fibrillation and other cardioembolic sources 1, 6
• Prolonged cardiac monitoring (Holter or event monitor) is reasonable if initial workup doesn't identify a clear cause 1
• Echocardiography should be considered, particularly if no other cause is identified 1, 6

Laboratory Tests

• Complete blood count, electrolytes, coagulation studies (aPTT, INR), renal function, glucose/HbA1c, lipid profile, and troponin 1

Your Risk Category and Urgency

Since you're presenting one week after symptom onset:

• You fall into the "lower risk" category for immediate recurrent stroke, as the highest risk period is within the first 48 hours 1
• However, you should still be evaluated by a neurologist or stroke specialist ideally within one month of symptom onset 1
• The early stroke risk after TIA is as high as 10% within the first week, so even at one week out, completing this evaluation remains important 5

Critical Pitfalls to Avoid

• Don't assume "normal" means no stroke risk - even if imaging is negative, you need the complete vascular and cardiac workup to identify treatable causes 1, 6
• Don't delay carotid imaging - if you had anterior circulation symptoms (weakness, speech problems), carotid stenosis must be ruled out urgently 5
• Don't skip the cardiac evaluation - atrial fibrillation is a major treatable cause requiring anticoagulation 1
• Ensure outpatient neurology follow-up is arranged before leaving the healthcare system 5

Practical Algorithm for Your Situation

1. Schedule brain MRI with DWI (or CT if MRI unavailable) 1
2. Obtain CTA of head and neck (or carotid ultrasound + transcranial Doppler) 1, 6
3. Get 12-lead ECG immediately 1
4. Complete basic laboratory workup 1
5. Arrange neurology follow-up within 2-4 weeks 1
6. Consider hospitalization if imaging reveals: acute infarction on DWI, large artery stenosis requiring intervention, or cardioembolic source 1, 5

The combination of MRI and vascular imaging provides the most complete picture of your stroke risk and guides optimal secondary prevention strategies, even when presenting a week after symptoms 1, 6.