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Brain Abscess

Andrew E. Auber1,  Clifford Belden1

1Brooke Army Medical Center, San Antonio, Texas

Publication Name: 
Current Protocols in Magnetic Resonance Imaging
Unit Number: 
Unit A4.1
DOI: 
10.1002/0471142719.mia0401s00
Online Posting Date: 
May, 2001
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Abstract

Magnetic Resonance Imaging (MRI) in cerebral abscess, as with most other forms of intracranial inflammatory or infectious diseases, is a powerful though largely nonspecific diagnostic tool. This unit presents a variant of a previously published standard imaging protocol, to include gadolinium-enhanced sequences for imaging of these patients. Several optional sequences, including diffusion (dMRI), perfusion (pMRI), and spectroscopic (MRS) sequences are outlined that can be employed should patient tolerance allow and if specific clinical situations require further clarification. The parameters given in this unit are derived from experience at 1.5 T and may need to be altered slightly depending on the field strength available and the specific equipment manufacturer.

     
 
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Table of Contents

  • Unit Introduction
  • Basic Protocol: Imaging of Cerebral Abscess
  • Alternate Protocol 1: Special Situations
  • Alternate Protocol 2: Imaging of Cerebral Abscess by Magnetic Resonance Diffusion, Perfusion, and Spectroscopy
  • Commentary
  • Bibliography
  • Figures
  • Tables
     
 
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Materials

Basic Protocol: Imaging of Cerebral Abscess

 Materials
  • Intravenous MRI contrast agent: gadolinium chelate (e.g., Magnevist,Omniscan, or Prohance)
  • Normal sterile saline (0.9% NaCl)

Alternate Protocol 2: Imaging of Cerebral Abscess by Magnetic Resonance Diffusion, Perfusion, and Spectroscopy

 Additional Materials
  • Enhanced gradient equipped MRI scanner
  • Specialized post-processing software, especially for pMRI image processing (a separate workstation is preferred for off-line processing of data sets, enabling continuous patient scanning to proceed)
  • Power injector for dynamic contrast administration (i.e., while scanning)
Looking for materials?  Suppliers Guide
     
 
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Figures

  • Figure A4.1.1
    A T2-weighted spin-echo transverse (TR = 2500 msec, TE = 80 msec, Nacq = 0.75) image of the brain (A) at the level of the midbrain shows several subtle abnormal foci of low signal intensity in the posterior brainstem and cerebellar peduncles (arrows) that on a gradient-echo coronal (TR = 500 msec, TE = 25 msec, Nacq = 1) image through the posterior midbrain (B) demonstrate marked magnetic susceptibility effect with “blooming” of the lesions (arrows). In addition there are numerous other foci demonstrated at multiple levels consistent with diffuse axonal injury in this 12-year-old boy who had sustained a severe closed head injury 2 months previously.

    View Image
  • Figure A4.1.2
    FLAIR (TR = 6000 msec, TE = 96 msec, Nacq = 1;TI = 1800 msec) and FSE T2-weighted (TR = 5616 msec, TE = 105 msec, Nacq = 1; echo train length = ETL = 12) transverse images (A,B) of the brain at the level of the corona radiata show an abnormal rounded low T2 signal intensity lesion (arrow) adjacent the left frontal horn of the lateral ventricle with surrounding edema. Precontrast (C) and post-contrast (D) transverse images at the same level (TR = 500 msec, TE = 12 msec, Nacq = 1) show intense enhancement of the lesion. The patient is a 41-year-old male with chronic sarcoidosis being treated with high-dose corticosteroids. The resulting chronic immunosuppression enabled infection and cerebral abscess formation by Bipolaris fungus. This patient previously underwent a left frontal lobe biopsy and resulting encephalomalacia is noted (asterisk). Magnetic resonance spectroscopy (PRESS, TR = 1600 msec, TE = 135 msec) of one of the abscesses (E) demonstrates a decrease in the NAA peak with elevation of the creatine and choline peaks consistent with a loss of neuronal tissue within the lesion.

    View Image
  • Figure A4.1.3
    FSE (TR = 3380 msec, TE = 90 msec, Nacq = 2; ETL = 8) T2-weighted (A) image through the occipital lobe shows a large heterogeneous lesion with prominent surrounding edema. There are layers of low T2 signal within its wall (arrows) suggesting not only abscess but possible microhemorrhage. The corresponding post-contrast T1-weighted (TR = 600 msec, TE = 14 msec, Nacq = 2) transverse (B) image reveals a relatively defined deep wall (arrow) compared to the more superficial wall (white arrow) and a target configuration (arrowhead), as well. This 40-year-old male with AIDS was treated for presumed toxoplasmosis with lesion resolution over the ensuing 8 weeks (not shown).

    View Image
  • Figure A4.1.4
    This 23-year-old female presented with headache and ataxia. (A) The FSE-T2 (TR = 5616 msec, TE = 105 msec, Nacq = 1; ETL = 8) and (B) post-contrast T1-weighted (TR = 500 msec, TE = 12 msec, Nacq = 1) transverse images show a heterogeneous rounded lesion of the right posterior midbrain (arrows) without definite enhancement. However, the transverse dMRI sequence (TR = 3000 msec, TE = 100 msec; b = 1000 sec/mm2) discloses corresponding high signal on the ADC map (C) and low signal on the diffusion-weighted image (D) compatible with a tumoral cyst. A low-grade astrocytoma was subsequently proven at surgical biopsy. This lesion presents a dMRI signal pattern opposite to that expected with cerebral abscess.

    View Image

Literature Cited

 Literature Cited
    Burtscher, I.M. and Holtas, S. 1999. In vivo proton MR spectroscopy of untreated and treated brain abscesses. Am. J.Neuroradiol. 20:1049-1053.
    Castillo, M. 1998. Neuroradiology Companion: Methods, Guidelines, and Imaging Fundamentals, 2nd ed. Lippincott New York.
    Desprechins, B., Stadnik, T., Koerts, G., Shabana, W., Breucq, C., and Osteaux, M. 1999. Use of diffusion-weighted MR imaging in differential diagnosis between intracerebral necrotic tumors and cerebral abscesses. Am. J. Neuroradiol. 20:1252-1257.
    Ernst, T.M., Chang, L., Witt, M.D., Aronow, H.A., Cornford, M.E., Walot, I., and Goldberg, M.A. 1998. Cerebral toxoplasmosis and lymphoma in AIDS: Perfusion MR experience in 13 patients. Radiology 208:663-669.
    Grand, S., Passaro, G., Ziegler, A., Esteve, F., Boujet, C., Hoffmann, D., Rubin, C., Segebarth, C., Decorps, M., Le Bas, J., and Remy, C. 1999. Necrotic tumor versus brain abscess: Importance of amino acids detected at 1H MR spectroscopy—initial results. Radiology 213:785-793.
    Mathisen, G.E. and Johnson, J.P. 1997. Brain abscess. Clin. Infect. Dis. 25:763-781.
    Orrison, W.W., Lewine, J.D., Sanders, J.A., and Hartshorne, M.F. 1995. Functional Brain Imaging. Mosby, St. Louis.
    Shellock, F.G. 1996. Pocket Guide to MR Procedures and Metallic Objects. Lippincott-, Philadelphia.
    Taveras, J.M. and Pile-Spellman, J. 1996. Inflammatory diseases. In Neuroradiology, 3rd ed. pp. 259-326. Williams and Wilkins, Baltimore, Maryland.
    Wong, J. and Quint, D.J. 1999. Imaging of central nervous system infections. Semin. Roentgenol. 34:123-143.
 Key References
    Orrison et al., 1995. See above

Contains lucid explanations for the physics and basic scan parameters of standard and advanced magnetic resonance imaging studies.

     
 
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