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Purpose To investigate the contribution of perfusion-weighted MR imaging (PWI) by using the relative cerebral blood volume (rCBV) ratio in the differential diagnosis of various intracranial space-occupying lesions. Materials and Methods This study involved 105 patients with lesions (high-grade glioma (N = 26), low-grade glioma (N= 11), meningioma (N = 23), metastasis (N = 25), hemangioblastoma (N = 6), pyogenic abscess (N = 4), schwannoma (N = 5), and lymphoma (N = 5)). The patients were examined with a T2*-weighted (T2*W) gradient-echo single-shot EPI sequence. The rCBV ratios of the lesions were obtained by dividing the values obtained from the normal white matter. Statistical analysis was performed with the Mann-Whitney U-test. A P-value less than 0.05 was considered statistically significant. Results The rCBV ratio was 5.76 ± 3.35 in high-grade gliomas, 1.69 ± 0.51 in low-grade gliomas, 8.02 ± 3.89 in meningiomas, 5.27 ± 3.22 in metastases, 11.36 ± 4.41 in hemangioblastomas, 0.76 ± 0.12 in abscesses, 1.10 ± 0.32 in lymphomas, and 3.23 ± 0.81 in schwannomas. The rCBV ratios were used to discriminate between 1) high- and low-grade gliomas (P < 0.001), 2) hemangioblastomas and metastases (P< 0.05), 3) abscesses from high-grade gliomas and metastases (P < 0.001), 4) schwannomas and meningiomas (P < 0.001), 5) lymphomas from high-grade gliomas and metastases (P < 0.001), and 6) typical meningiomas and atypical meningiomas (P < 0.01). Conclusion rCBV ratios can help discriminate intracranial space-occupying lesions by demonstrating lesion vascularity. It is possible to discriminate between 1) high- and low-grade gliomas, 2) hemangioblastomas and other intracranial posterior fossa masses, 3) abscesses from high-grade gliomas and metastases, 4) schwannomas and meningiomas, 5) lymphomas and high-grade gliomas and metastases, and 6) typical and atypical meningiomas. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc.

In this study, we investigated the relationship between genetic alterations such as chromosome 22 aneuploidy and p53 gene deletion, and the pathological types of meningioma of typical and aggressive forms. Thirty-four meningiomas (23 typical and 11 aggressive) were examined by application of fluorescence in situ hybridization (FISH) with chromosome 22 specific alpha satellite probe and a combination of p53 locus specific and chromosome 17 centromere specific alpha satellite probes, to evaluate the chromosome 22 aneuploidy and gain or loss of p53 gene along with chromosome 17. The results showed that, although chromosome 22 aneuploidy was seen in 7 out of 23 typical (30.4%) and 4 out of 11 aggressive meningiomas (36.3%), no p53 deletion was detected in typical meningiomas, and p53 deletion was detected in 3 out of 11 aggressive meningiomas (1 atypical and 2 malignant), which had recurrence. There were no simultaneous occurrences of p53 gene deletions between typical and aggressive meningiomas. The present findings indicate that the loss of chromosome 22 may be involved with tumorogenesis of typical and aggressive meningiomas, while p53 gene deletions may be involved with malignant progression and recurrence in the aggressive meningiomas.

Introduction 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. Conclusion 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.

PURPOSE: In recent years there have been many attempts to define a subset of aggressive malignant meningiomas based on histopathology and imaging technologies. The purpose of this study was to evaluate the level of peritumoral edema and its volume using the imaging technologies, computer tomography and magnetic resonance imaging, and correlate these results with the histological WHO classification. Reported causes of tumoral edema and its relationships to the histological characteristics were also reviewed. METHODS: The cases of 55 patients with meningiomas who underwent surgery at the Hospital das Clinicas (Fac Med Univ Sao Paulo) between September 1993 and September 1997 were reviewed. The level of edema according to the classification of Ide et al. (1995) was compared to the histological WHO classification. RESULTS: Classification of the degree of edema was: level 0 edema - 28 cases ; level I edema - 19 cases; level II edema - 8 cases. Histological classification was: benign meningioma - 43 cases; atypical meningiomas - 11 cases; malignant meningioma - 1 case. There was a significant (P = .0089) correlation between the degree of tumoral edema and the histological characteristics. CONCLUSIONS: These results suggest that the degree of edema as revealed by computer tomography and magnetic resonance imaging can be an important clinical predictive factor for the histological grade of the meningioma. OBJETIVO: Nos últimos anos têm-se descrito alguns subtipos de meningiomas de comportamento peculiarmente agressivo. Muitas tentativas têm sido feitas no intuito de estabelecer critérios imagenológicos ou histopatológicos de malignidade. O objetivo desse estudo é avaliar, através de Tomografia Computadorizada e Ressonância Nuclear Magnética o grau de edema peritumoral e seu volume, correlacionando-os com a classificação histológica da OMS. As causas relatadas de edema peritumoral e sua possível correlação histológica foram também revistos. MÉTODOS: Foram estudados 55 casos de meningiomas operados no Hospital das Clinicas (FMUSP) entre Setembro de 1993 e Setembro de 1997. O grau de edema segundo a classificação de Ide et al. (1995) foi comparado com a classificação da OMS. RESULTADOS: Os achados relativos a edema foram: edema grau 0 - 28 pacientes; grau I - 19 pacientes; grau II - 8 pacientes. A classificação histológica demonstrou: meningiomas benignos - 43 casos; meningiomas atípicos - 11 casos meningioma maligno - 1 caso. Demonstrou-se uma correlação significativa (p = 0,0089) entre o grau de edema dos meningiomas e suas características histológicas. CONCLUSÕES: Esses resultados sugerem que o grau de edema avaliado imagenologicamente pela Tomografia Computadorizada e Ressonância Nuclear Magnética pode ser um importante fator preditivo da gradação histológica dos meningiomas.