title: Meningiomas with conventional MRI findings resembling intraaxial tumors: can perfusion-weighted MRI be helpful in differentiation?
abstract: BACKGROUND
  To investigate the contribution of perfusion-weighted MRI to the differentiation of meningiomas with atypical conventional MRI findings from intraaxial tumors.
  
  
  METHODS
  We retrospectively analyzed 54 meningiomas, 12 glioblastomas and 13 solitary metastases. We detected 6 meningiomas with atypical features on conventional MRI resembling intraaxial tumors. The regional cerebral blood flow (rCBV) ratios of all tumors were calculated via perfusion-weighted MRI. The signal intensity-time curves were plotted and three different curve patterns were observed. The type 1 curve resembled normal brain parenchyma or the postenhancement part was minimally below the baseline, the type 2 curve was similar to the type 1 curve but with the postenhancement part above the baseline, and the type 3 curve had the postenhancement part below the baseline accompanied by widening of the curve. Student's t-test was used for statistical analysis.
  
  
  RESULTS
  On CBV images meningiomas were hypervascular and the mean rCBV ratio was 10.58+/-2.00. For glioblastomas and metastatic lesions, the rCBV ratios were 5.02+/-1.40 and 4.68+/-1.54, respectively. There was a statistically significant difference in rCBV ratios between meningiomas and glioblastomas and metastases (P<0.001). Only one of the meningiomas displayed a type 2 curve while five showed a type 3 curve. Glioblastomas and metastases displayed either a type 1 or a type 2 curve. None of the meningiomas showed a type 1 curve and none of the glioblastomas or metastases showed a type 3 curve.
  
  
  CONCLUSIONS
  Differentiating meningiomas with atypical conventional MRI findings from malignant intraaxial tumors can be difficult. Calculation of rCBV ratios and construction of signal intensity-time curves may contribute to the differentiation of meningiomas from intraaxial tumors.
authors.affiliation: Department of Radiology, Uludag University Medical School, Bursa, Turkey. bahattinh@hotmail.com
authors.forename: Bahattin
authors.initials: B
authors.lastname: Hakyemez
authors.forename: Nalan
authors.initials: N
authors.lastname: Yildirim
authors.forename: Cüneyt
authors.initials: C
authors.lastname: Erdoğan
authors.forename: Hasan
authors.initials: H
authors.lastname: Kocaeli
authors.forename: Ender
authors.initials: E
authors.lastname: Korfali
authors.forename: Mufit
authors.initials: M
authors.lastname: Parlak
mesh_terms: D000368:Aged; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000503:physiopathology / Q000556:secondary; D002560:Cerebrovascular Circulation / Q000502:physiology; D003937:Diagnosis, Differential; D005260:Female; D005909:Glioblastoma / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008577:Meningeal Neoplasms / Q000175:diagnosis* / Q000503:physiopathology; D008579:Meningioma / Q000175:diagnosis* / Q000503:physiopathology; D008875:Middle Aged; D012189:Retrospective Studies