What is the best imaging modality to diagnose a spinal cord infarct?

Best Imaging to Diagnose Spinal Cord Infarct

MRI of the spine without and with IV contrast, including diffusion-weighted imaging (DWI), is the best imaging modality to diagnose spinal cord infarction. 1

Primary Imaging Protocol

MRI spine with the following sequences is mandatory:

• T2-weighted imaging demonstrates the classic "pencil-like" hyperintensity along the affected cord segments in virtually all cases (sensitivity approaching 100% after 24 hours) 1, 2

• Diffusion-weighted imaging (DWI) is essential because it detects spinal cord ischemia earlier than conventional T2-weighted sequences—often within hours of symptom onset when T2 images may still be normal 1, 3, 4

• Apparent diffusion coefficient (ADC) maps show corresponding hypointensity (restricted diffusion) with ADC values typically 0.23-0.86 × 10⁻³ mm²/s, significantly lower than normal cord tissue 4, 5, 6

• Gadolinium contrast administration helps exclude inflammatory or infectious etiologies, as spinal cord infarction typically shows no enhancement in the acute phase (first 24-48 hours), whereas inflammatory conditions like transverse myelitis usually enhance 1

Critical Timing Considerations

The imaging findings evolve predictably over time, which affects diagnostic accuracy:

• Within first 12 hours: DWI shows restricted diffusion (hyperintense on DWI, hypointense on ADC) even when T2-weighted images may be normal 3, 4

• 24 hours to 1 week: Both DWI and T2-weighted images show abnormalities; this is the optimal diagnostic window 3, 5

• After 1 week: DWI undergoes "pseudonormalization" (restricted diffusion resolves), making T2-weighted images the primary diagnostic sequence at this stage 3, 5

Characteristic MRI Features of Spinal Cord Infarction

On sagittal T2-weighted images:

• "Pencil-like" or "strip-like" hyperintensity along the longitudinal axis of the cord 5, 2
• Cord enlargement in approximately 56-63% of cases 5, 2
• Lesion length typically 1-2 vertebral segments (shorter than inflammatory myelitis) 6

On axial T2-weighted images:

• Bilateral hyperintensity in the anterior spinal artery (ASA) territory in 94% of cases 2
• "Owl's eyes" sign (bilateral anterior horn involvement) indicates poor prognosis 7
• Posterior spinal artery territory involvement is rare (6% of cases) 2

On DWI:

• 100% sensitivity in acute phase (first week) 6
• Better lesion-to-background contrast than T2-weighted imaging 5
• Can show "owl's eyes sign" and "pencil-like hyperintensity" earlier than T2 sequences 6

Key Differentiating Features from Inflammatory Myelitis

DWI and ADC maps are particularly valuable for distinguishing spinal cord infarction from neuromyelitis optica spectrum disorder (NMOSD):

• Spinal cord infarction: DWI hyperintensity with ADC hypointensity (restricted diffusion) 6
• NMOSD: DWI hyperintensity with ADC isointensity or hyperintensity (T2 shine-through effect, not true restricted diffusion) 6
• Lesion length: Infarction typically ≤2 vertebral segments; NMOSD typically ≥3 segments (longitudinally extensive transverse myelitis) 6
• Contrast enhancement: Absent in acute infarction; present in most inflammatory conditions 1, 5

Common Pitfalls to Avoid

• Do not rely on CT or radiography—these modalities cannot adequately visualize the spinal cord parenchyma and will miss the diagnosis 1

• Do not omit DWI sequences—conventional MRI alone may be normal in up to 45% of cases in the first 24 hours, whereas DWI detects ischemia within hours 1, 4

• Do not skip contrast administration—while infarction itself doesn't enhance acutely, contrast is necessary to exclude inflammatory mimics that require different treatment 1

• Do not image only the symptomatic level—image the entire spine initially, as clinical localization can be imprecise and multiple levels may be involved 1

Follow-Up Vascular Imaging

After confirming spinal cord infarction on MRI, MR angiography (MRA) of the spine should be considered to identify:

• Vertebral artery dissection or occlusion 1
• The artery of Adamkiewicz 1
• Spinal vascular malformations (though these more commonly present with hemorrhage) 1

However, MRA is not a first-line test and should only be obtained after the diagnosis is established on conventional MRI with DWI 1

Most Vulnerable Spinal Cord Levels

Contrary to traditional teaching about thoracolumbar watershed zones, recent evidence shows:

• Cervical cord (especially C2-C3): 44% of cases 2
• Thoracolumbar region (T10-L1) including conus medullaris: 44% of cases 2
• Upper thoracic (T3-T5): 12% of cases 2

This distribution should guide focused imaging when clinical localization is unclear 2