American Journal of Neuroradiology

[Guest guest]

American Journal of Neuroradiology 26:1115-1121, May 2005

© 2005 American Society of Neuroradiology

http://www.ajnr.org/cgi/content/abstract/26/5/1115

BRAIN

Diffusion-Weighted Imaging of Fungal Cerebral Infection

Paola Gaviania, B. Schwartze,g, E. Tessa Hedley-Whyteb,g,

L. Ligonf,g, Ari Robicsekc, Pamela Schaeferd,g and W.

Hensona,d,g

a E. and Pappas Center for Neuro-oncology Unit,

Massachusetts General Hospital, Boston

b E. and Pappas Center for Neuropathology Unit,

Massachusetts General Hospital, Boston

c E. and Pappas Center for Infectious Disease

Unit, Massachusetts General Hospital, Boston

d Division of Neuroradiology, Massachusetts General Hospital, Boston

e Division of Neuroradiology, Brigham and Women's Hospital, Boston

f Division of Neuropathology, Brigham and Women's Hospital, Boston

g Harvard Medical School, Boston

Address reprint requests to W. Henson, MD, E. and

Pappas Center for Neuro-oncology and Division of

Neuroradiology, Massachusetts General Hospital, Yawkey 9E, Fruit

Street, Boston, MA 02114

BACKGROUND AND PURPOSE: Diffusion-weighted imaging (DWI) is useful

in diagnosing bacterial brain abscesses, but DWI features of fungal

brain abscesses have not been characterized. Because fungal

abscesses are not purulent, we hypothesized that their DWI

characteristics are distinct from those of bacterial abscesses.

METHODS: We reviewed clinical, neuropathologic and neuroimaging

findings of patients with fungal brain infections due to Aspergillus

(n = 6), Rhizopus (n = 1), or Scedosporium (n = 1) species. DWI and

apparent diffusion coefficient (ADC) maps were obtained before

definitive diagnosis and antifungal therapy. ADC ratios

(lesion/contralateral white matter) were calculated.

RESULTS: Two patients had a rapidly progressive, fatal course, with

cerebritis and acute inflammation; fungal organisms were largely

restricted to vessels. Lesions were predominantly nonenhancing and

had heterogeneous foci of restricted diffusion. Six patients with

subacute neurologic presentations had acute or chronic inflammation,

capsule formation, focal necrosis, and fungal organisms disseminated

throughout the lesion. Their abscesses were ring enhancing. In five,

lesions had restricted diffusion in the central nonenhancing

portions. The sixth patient had a lesion with a peripheral rim of

restricted diffusion but elevated central diffusion; histopathology

showed early abscess formation. Mean ADC for all lesions was 0.33 ±

0.06 x 10–3 mm2/s, with an average ADC ratio of 0.43.

CONCLUSION: Fungal cerebral abscesses may have central restricted

diffusion similar to that of bacterial abscesses but with histologic

features of acute or chronic inflammation and necrosis rather than

suppuration. Altered water diffusion in these lesions likely

reflects highly proteinaceous fluid and cellular infiltration.