Imaging

Brain Abscess

Preliminary Diagnosis: Brain Abscess

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

  • Multiplanar MRI with and without contrast

II. Describe the advantages and disadvantages of this technique for diagnosis of brain abscess.

Advantages

  • Most sensitive examination for brain abscess

  • Best anatomic resolution for brain imaging

  • Can depict early changes (cerebritis) that precede discrete abscess formation

  • MR spectroscopy can be performed to detect metabolites that may help confirm diagnosis

  • Can detect associated findings such as meningitis, ventriculitis, and multifocal abscesses and can delineate the degree of mass effect/herniation

  • No ionizing radiation

Disadvantages

  • Imaging alone may not be diagnostic. Several other entities can present as ring-enhancing lesions on MRI.

  • Requires patient cooperation to minimize motion artifact as the examination time is lengthy

  • Expensive

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

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

MRI is contraindicated in patients with non-MRI-compatible metallic implants and foreign bodies.

IV. What alternative imaging techniques are available?

CT brain with and without IV contrast

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

CT brain with and without IV contrast

Advantages

  • Examination can be obtained quickly, which reduces the chances of significant motion artifact in an uncooperative patient

  • Can better delineate bony changes when abscess is secondary to a more superficial process, such as sinusitis or trauma

Disadvantages

  • Decreased sensitivity and anatomic detail compared with MRI

  • Adequate renal function required for IV contrast administration, generally creatinine <1.7

  • Uses ionizing radiation

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

CT is contraindicated in pregnant patients.

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