AJR 2001; 177:721-722
© American Roentgen Ray Society
An Unusual Central Nervous System Manifestation of Behçet's Disease
Sergi Ganau,
Joan Berenguer,
Teresa Pujol and
Josep M. Mercader
Hospital Clínic Barcelona Barcelona
08036, Spain
A 34-year-old man who had experienced a previous episode of cerebral
involvement of Behçet's disease presented with
a 9-day history of a throbbing headache and progressive right hemiparesis. CT
scans and conventional MR images showed an isointense lesion with a
hypointense 2-cm central area with ringlike contrast enhancement on
T1-weighted images (Fig. 4A) in
the left frontal region. This central area appeared slightly hyperintense on
T2-weighted images. Perilesional edema was also observed. Echoplanar MR
imaging and MR spectroscopy were performed, with the findings revealing the
possibility of a brain abscess. Diffusion-weighted images showed a bright
cavity and a markedly decreased apparent diffusion coefficient with
perilesional edema (Fig. 4B).
Perfusion MR imaging revealed that regional cerebral blood volume was
substantially decreased throughout the lesion. MR spectroscopy showed
end-products of bacterial breakdown (acetate, cytosolic amino acids, lactate,
and succinate) (Fig. 4C). Blood
and cerebrospinal fluid cultures were negative, and the patient was
empirically treated with antibiotics and corticosteroids, substantially
improving the symptoms. Follow-up CT and conventional MR studies revealed a
slight increase in the left frontal lesion. Neurosurgery was then performed,
revealing an abscess in which gram-positive cocci were identified.
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Fig. 4A. —34-year-old man with Behçet's
disease. Contrast-enhanced axial T1-weighted image (TR/TE range, 3300/24-83,
number of excitations, 2) shows ring contrast-enhancing lesion in the frontal
region with perilesional hypointense edema. Hypointense residual lesion, which
corresponds to previous vasculitic episode, is shown in right hemisphere.
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Fig. 4B. —34-year-old man with Behçet's
disease. Diffusion-weighted image (TR/TE, 8000/105; b value, 1000
sec/mm2) reveals increased signal in left frontal region surrounded
by hypointensity that corresponds to edema.
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Fig. 4C. —34-year-old man with Behçet's
disease. Proton spectrum obtained by point-resolved spectroscopy (Probe-SV;
General Electric Medical Systems, Milwaukee, WI; TR/TE, 1500/288, number of
excitations, 8) from lesion shows resonances representing (from right to left)
cytosolic amino acids (AA), lactate (Lac), alanine (Ala), acetate (Ac), and
succinate (Succ).
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Central nervous system involvement in
Behçet's disease is reported in 4-49% of all
patients [1]. Lesions are
mostly due to vasculitic processes. MR imaging is more sensitive in revealing
them than CT is. Nonhemorragic lesions are the most typical, and they are
usually hypointense on T1-weighted images and hyperintense on T2-weighted
images. Some of the lesions are enhanced after contrast media administration.
Homogeneous, heterogeneous, linear, circular, and ring patterns have been
described. In our patient, the findings on conventional MR imaging were rather
similar to those reported in the literature
[1,
2]. To our knowledge,
echoplanar MR imaging and spectroscopic findings in
Behçet's disease have not been previously
described.
Desprechins et al. [3]
described the diagnostic clue of diffusion-weighted MR images in patients with
cerebral "ring-enhancing" masses. The authors reported three cases
of brain abscesses with hyperintensity in the necrotic component
[3]. Ernst et al.
[4] reported reduced regional
cerebral blood volume in toxoplasmatic lesions and attributed that finding to
a probable lack of vasculature in the abscess. On MR spectroscopy, lactate
(1.3 parts per million) is often observed because of the necrotic tissue, but
it is not pathognomonic for abscesses. Nevertheless, the presence of cytosolic
amino acids (0.9 parts per million), acetate (1.9 parts per million), and
succinate (2.4 parts per million) is highly suggestive of abscesses
[5]. These findings in a
patient with Behçet's disease suggested a
brain abscess.
In our patient, diffusion-weighted imaging, perfusion imaging, and
spectroscopy contributed substantially to our making the correct
diagnosis.
References
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Koçer N, Islak C, Siva A, et al.
CNS involvement in neuro-Behçet syndrome: an
MR study. AJNR
1999;20:1015
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Tali ET, Atilla S, Keskin T, Simonson T, Isik S, Yuh WTC. MRI in
neuro-Behçet's disease.
Neuroradiology
1997;39:2
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Desprechins B, Stadnik T, Koerts G, Shabana W, Breucq C, Osteaux M.
Use of diffusion-weighted MR imaging in differential diagnosis between
intracerebral necrotic tumors and cerebral abscesses.
AJNR
1999;20:1252
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Ernst T, Chang L, Witt MD, et al. Cerebral toxoplasmosis and
lymphoma in AIDS: perfusion MR imaging experience in 13 patients.
Radiology
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Burtscher IM, Holtas S. In vivo proton MR spectroscopy of untreated
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1999;20:1049
-1053[Abstract/Free Full Text]
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