Imaging

Epidural Abscess

Preliminary Diagnosis: Epidural Abscess

I. What imaging technique is first-line for this diagnosis

MRI of the spine with and without contrast. STIR and post-contrast fat-saturated images should be included.

II. Describe the advantages and disadvantages of this technique for diagnosing epidural abscess.

Advantages

  • Highest sensitivity for detecting epidural abscess.

  • Can detect early signs of infection, such as epidural thickening, before a discrete abscess forms.

  • Can detect signal alteration in the spinal cord and narrowing of the neural foramina.

Disadvantages

  • Requires significant patient cooperation to minimize motion artifact, as the exam time is lengthy.

  • Expensive.

  • Adequate renal function with GFR >60 is needed for IV contrast administration. Patients with GFR 30-60 can be evaluated for contrast administration on a case-by-case basis.

III. What are the contraindications for the first-line imaging technique?

Contraindicated in patients with non-MRI compatible metallic hardware or foreign bodies.

IV. What alternative imaging techniques are available?

  • CT of the spine with intravenous contrast

  • CT Myelography

V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of epidural abscess.

CT of the spine with intravenous contrast

Advantages

  • Can be obtained quickly, reducing chances of significant motion artifact in an uncooperative patient.

Disadvantages

  • Less sensitive and specific for detection of abscess compared to MRI.

  • Requires adequate renal function for administration of IV contrast, generally creatinine <1.7.

  • Utilizes ionizing radiation.

CT myelography

Advantages

  • Better at detecting deformity of the thecal sac and block of CSF flow than CT with IV contrast.

Disadvantages

  • Requires lumbar puncture for administration of intrathecal contrast.

  • Not specific for abscess. Herniated disc or epidural hematoma can produce similar imaging findings.

  • Utilizes ionizing radiation.

VI. What are the contraindications for the alternative imaging techniques?

CT of the spine with intravenous contrast

  • Contraindicated in pregnant patients.

CT Myelography

  • Contraindicated in pregnant patients.

  • Contraindicated in patients with platelets <50,000 or INR >1.7 due to risk of epidural hematoma secondary to lumbar puncture.

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