Microcystic meningiomas: radiological characteristics of 16 cases.
BACKGROUND
As a rare subtype of meningioma, only a few reports deal with radiological characteristics of microcystic meningiomas and the problem remains controversial. The authors have analyzed the radiological findings of a series of microcystic meningiomas with a special focus on magnetic resonance images (MRI) and conventional angiography.


METHODS
Sixteen patients of histologically proven microcystic meningiomas were included. Analysis of preoperative MRI including signal intensity characteristics, enhancement patterns and peritumoural edema were performed and correlated with angiographic and histological findings. Peritumoural edema was graded using edema index (EI) which was defined as the ratio of VE/VT.


RESULTS
The tumours were uniformly visualized as a high-signal mass lesion in T2-weighted images and as a low-signal mass lesion in T1-weighted images regardless of tumour vascularity shown by angiography. T2-weighted images revealed that peritumoural brain edema was severe in 11, moderate in 1, mild in 2 and negligible in 2 patients and this was closely related to the co-existence of irregular tumour marginal enhancement. However, other features failed to distinguish these lesions from other subtypes of meningioma.


CONCLUSIONS
The cases presented demonstrate that characteristic MRI findings suggestive of microcystic meningiomas are; (1) low signal intensity mass in T1- and high signal intensity mass in T2-weighted images; (2) high incidence of peritumoural edema.
Paek
S H
SH
Department of Neurosurgery and Clinical Research Institute, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea.
Kim
S H
SH
Chang
K H
KH
Park
C-K
CK
Kim
J E
JE
Kim
D G
DG
Park
S-H
SH
Jung
H-W
HW
D000328:Adult; D000368:Aged; D001929:Brain Edema / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology; D002533:Cerebral Angiography / Q000379:methods; D002536:Cerebral Arteries / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008577:Meningeal Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000473:pathology*; D008579:Meningioma / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000473:pathology*; D008875:Middle Aged; D011237:Predictive Value of Tests; D014057:Tomography, X-Ray Computed / Q000379:methods