MR characteristics of meningioma subtypes at 1.5 tesla

Microcystic Meningiomas: MRI-Pathologic Correlation

BACKGROUND AND PURPOSE

Microcystic meningiomas (MM) are a distinctive, rare subtype of Grade I meningiomas with limited radiological descriptions. We intend to identify unique imaging phenotypes and seek radiopathological correlations.

METHODS

Retrospective analysis of histopathologically proven MM was undertaken. Clinicodemographic profiles, imaging, and histopathological characteristics were recorded. Spearman rank correlations among radiological and pathological attributes were performed.

RESULTS

Twenty-eight cases were analyzed (mean age = 45.5 years; M:F = 1:1.54; mean volume = 50.1 mL; supratentorial n = 27). Most lesions were markedly T2 hyperintense (higher than peritumoral brain edema-a unique finding) (89.3%) and showed invariable diffusion restriction, severe peritumoral brain edema (edema index >2 in 64.3%), a "storiform" pattern on T2-weighted images (T2WI) (75%), reticular pattern on postcontrast T1 (78.6%)/diffusion-weighted images (DWI) (65.4%), hyperperfusion, T1 hypointensity (84.6%), and absence of blooming on susceptibility-weighted image (80.9%). Storiform/reticular morphology correlated with large cysts on histopathology (ρ = .56; P = .005753).  Lesion dimension positively correlated with reticular morphology on imaging (ρ = .59; P = .001173), higher flow voids (ρ = .65; P = .00027), and greater microcystic changes on histopathology (ρ = .51; P = .006778). Peritumoral brain edema was higher for lesions demonstrating greater angiomatous component (ρ = .46; P = .014451).

CONCLUSIONS

We have elucidated varied neuroimaging features and highlighted pathological substrates of crucial imaging findings of MM. MM ought to be considered as an imaging possibility in an extra-axial lesion with a marked hypodensity on noncontrast computed tomography, markedly T2-hyperintense/T1-hypointense signal, and a storiform/reticular pattern on T2W/GdT1w//DWI.

Evaluation of Epidemiologic Factors, Radiographic Features, and Pathologic Findings for Predicting Peritumoral Brain Edema in Meningiomas

BACKGROUND

Despite several treatment options that are available for meningiomas, surgery is the only method currently practiced. Peritumoral brain edema (PTBE) in meningiomas causes difficulty marginalizing the dissection in an intraoperative setting.

PURPOSE

To evaluate whether the epidemiological variables, imaging characteristics, and pathologic parameters are correlated with the presence of PTBE in meningiomas.

STUDY TYPE

Retrospective study from 2015 to 2018.

SUBJECTS

In all, 550 patients with histopathologically confirmed meningioma were included. After exclusion of patients with extradural, spinal, and intraventricular meningiomas and those with image artifacts, a total of 441 patients were included in the final analysis.

FIELD STRENGTH/SEQUENCE

Images were performed with 3T MR scanners and axial/sagittal T₁ WI, axial/coronal T₂ WI and axial/sagittal/coronal contrast-enhanced T₁ WI after administration of 0.1 mmol/kg of body weight of Gd-DTPA.

ASSESSMENT

Fourteen variables were patients' age, sex, skull changes, calcification, density, location, margin, volume, cerebrospinal fluid (CSF) cleft, signal intensity (SI) on T₂ WI, degree and pattern of contrast enhancement, WHO histological classification, and Ki-67 labeling index.

STATISTICAL TESTS

The relationship between each factor and the formation of PTBE was examined by multivariate logistic regression analysis.

RESULTS

After multivariate logistic regression, the absence of CSF cleft (odds ratio [OR]: 63.43, 95% confidence interval [CI]: 27.24-121.42, P = 1.2 × 10^-8 ), non-skull base location (OR: 15.32, 95% CI: 5.81-28.23, P = 0.0008), high SI on T₂ WI (OR: 5.05, 95% CI: 2.27-14.88, P = 0.01), and G I uncommon subtypes (OR: 4.75, 95% CI: 1.42-15.94, P = 0.01) were found to be significant independent factors associated with the occurrence of PTBE in meningiomas. In patients with PTBE-positive meningiomas, there was no significant correlation between the volume of PTBE and the volume of the tumor (r = 0.17, P = 0.60).

DATA CONCLUSION

These factors may be suggestive of anticipating the formation of PTBE.

LEVEL OF EVIDENCE

3 Technical Efficacy Stage: 3 J. Magn. Reson. Imaging 2020;52:174-182.

Are convexity meningiomas all the same? A clinico-radiological analysis of surgically treated eloquent areas convexity meningiomas

BACKGROUND

Convexity meningiomas are considered low-risk tumors, with high possibility of cure and low risk of relapse after resection. Very few studies have investigated meningiomas located in or around highly eloquent regions (namely perirolandic and perisylvian fissures). This study aimed to determine the differences in preoperative characteristics and postoperative outcomes between convexity meningiomas at eloquent area and non-eloquent areas.

METHODS

Retrospective study on patients who underwent surgical resection for convexity meningioma. Patients were divided into eloquent and non-eloquent area. Statistical analysis was made comparing preoperative and postoperative data of both groups.

RESULTS

The study included a total of 117 patients: 80 with eloquent area tumor and 37 with non- eloquent area tumor. Statistically significant differences were detected between the groups in preoperative KPS (93 ± 10 in eloquent vs. 97 ± 6 in non-eloquent; p = .008) and in large-caliber vein involvement (76.3% in cases vs. 16.2% in controls; p < .001). Postoperatively, patients with eloquent area tumors showed initial deterioration in neurological status followed by recovery; final outcomes were comparable to that of patients with non-eloquent area tumors. However, patients with eloquent area meningiomas had higher propensity to suffer from seizures postoperatively. Postoperative complications and long-term outcomes were not significantly different between the two groups.

CONCLUSIONS

Patients with eloquent areas convexity meningiomas do not appear to have higher surgical risk. Neurological status is more likely to worsen immediately after surgery but long-term recovery is satisfactory. Seizure control after surgery appears to be poorer in patients with perirolandic meningioma.

Sclerosing Meningioma : Radiological and Clinical Characteristics of 21 Cases

Objective

A rare subtype of meningioma, sclerosing meningioma is not included in the current World Health Organization classification of meningiomas and is classified into the category of other morphological variation subtypes. Sclerosing meningioma is often misdiagnosed to other non-benign meningioma or malignant neoplasm, so it is important to diagnose sclerosing type correctly. We analyzed the radiological and clinical characteristics of a series of sclerosing meningiomas.

Methods

Twenty-one patients who underwent surgery in one institute with a histopathologically proven sclerosing meningioma were included from 2006 to 2014. Eighteen tumors were diagnosed as a pure sclerosing-type meningioma, and 3 as mixed type. Magnetic resonance image was taken for all patients including contrast enhancement image. Computed tomography (CT) scan was taken for 16 patients. One neuroradiologist and 1 neurosurgeon reviewed all images retrospectively.

Results

In the all 16 patients with preoperative CT images, higher attenuation was observed in the meningioma than in the brain parenchyma, and calcification was observed in 11 (69%). In 15 of the 21 patients (71%), a distinctive very low signal intensity appeared as a dark color in T2-weighted images. Nine of these 15 tumors (60%) exhibited heterogeneous enhancement, and 6 (40%) exhibited homogeneous enhancement that was unlike the homogeneous enhancing pattern shown by conventional meningiomas. Ten patients had a clear tumor margin without peritumoral edema.

Conclusion

Although these peculiar radiological characteristics are not unique to sclerosing meningioma, we believe that they are distinctive features that may be helpful for distinguishing sclerosing meningioma from other subtypes.

Spinal osteoblastic meningioma with hematopoiesis: radiologic-pathologic correlation and review of the literature

Spinal meningiomas associated with bone formation and hematopoiesis are rare tumors with only 3 prior case reports in the literature. We describe a case report of a woman who presented with back pain and an isolated event of urinary incontinence. A calcified spinal canal mass at T8 was identified on computed tomographic and magnetic resonance imaging. A gross total resection of the tumor was performed and pathologic examination showed a meningioma, World Health Organization grade 1, containing bone and bone marrow elements. A review of previously reported cases and a discussion of possible mechanisms of bone and hematopoiesis development in meningioma are presented.

Preoperative radiologic classification of convexity meningioma to predict the survival and aggressive meningioma behavior

Background

A subgroup of meningioma demonstrates clinical aggressive behavior. We set out to determine if the radiological parameters can predict histopathological aggressive meningioma, and propose a classification to predict survival and aggressive meningioma behavior.

Methods

A retrospective review of medical records was conducted for patients who underwent surgical resection of their convexity meningioma. WHO-2007 grading was used for histopathological diagnosis. Preoperative radiologic parameters were analyzed, each parameter was scored 0 or 1. Signal intensity on diffusion weighted MRI (DWI) (hyperintensity=1), heterogeneity on T1-weighted gadolinium enhanced MRI (heterogeneity=1), disruption of arachnoid at brain-tumor interface=1and peritumoral edema (PTE) on T2-weighted MRI (presence of PTE=1) and tumor shape (irregular shape=1). Multivariate logistic regression analyses were conducted to determine association of radiological parameters to histopathological grading. Kaplan-Meier and Cox regression models were used to determine the association of scoring system to overall survival and progression free survival (PFS). Reliability of the classification was tested using Kappa co-efficient analysis.

Results

Hyperintensity on DWI, disruption of arachnoid at brain-tumor interface, PTE, heterogenicitiy on T1-weighted enhanced MRI and irregular tumor shape were independent predictors of non-grade I meningioma. Mean follow-up period was 94.6 months (range, 12-117 months). Median survival and PFS in groups-I, II and III was 114.1±1.2 and 115.7± 0.8, 88± 3.3 and 58.5±3.9, 43.2± 5.1 and 18.2±1.7 months respectively. In cox regression analysis model, age (P<0.0001, OR–1.039, CI-1.017-0.062), WHO non-grade-I meningioma (P=0.017, OR–3.014, CI-1.217-7.465), radiological classification groups II (P=0.002, OR–6.194, CI–1.956-19.610) and III (P<0.0001, OR–21.658, CI–5.701-82.273) were independent predictors of unfavorable survival outcomes.

Conclusions

Preoperative radiological classification can be used as a supplement to the histopathological grading. Group-I meningiomas demonstrate benign radiological, histopathological and clinical features; group-III demonstrates aggressive features. Group-II meningiomas demonstrate intermediate features; the need for more aggressive follow-up and/or treatment should be further investigated.

Spinal accessory neuropathy associated with the tumor located on the jugular foramen

Spinal accessory neuropathy is commonly caused by iatrogenic injury or secondary to trauma or infection. Nevertheless, the tumor related palsy is rare. We present a case of an 18-year-old male patient suffering from paralysis of his right trapezius and sternocleidomastoid muscle. An electrophysiologic diagnostic study confirmed the spinal accessory neuropathy of the proximal segment. In addition, magnetic resonance imaging showed the location of tumor on the jugular foramen. However, the type of the tumor was not confirmed through biopsy because the patient refused surgical procedure. Based on the study, it is hypothesized that the tumor located on the jugular foramen should be considered as a cause of the spinal accessory nerve of the proximal segment.

Primary esophageal meningioma: first literature report

We have described a primary esophageal meningioma (MG) clinical case diagnosed in a 62-year-old woman; also, we review the literature about extracranial MGs. To our knowledge, this is the first case report of an extracranial MG occurring primarily in the esophagus. These are benign neoplasms reported classically in the central nervous system (CNS). The extrancranial MGs have histopathologic and inmunohistochemical features identical to those observed in CNS MGs; thus, the main diagnostic hurdle is to keep it in the differential for lesions occurring outside the CNS.

Predictors of meningioma consistency: A study in 243 consecutive cases

BACKGROUND

Meningioma is a common neoplasm primarily arising in the central nervous system. Its consistency is considered to be one of the critical prognostic factors for determining surgical resectability. The present study endeavored to investigate predictive factors associated with the tumor consistency.

METHODS

Two hundred and forty-three consecutive participants who underwent resective surgery of meningioma were examined. The authors designed an objective grading system for meningioma consistency and utilized it for assessing consistency among all cases. We focused on the relationship between preoperative tumor characteristics on neuroimaging studies and the consistency.

RESULTS

The tumor attributes on T2-weighted image (T2WI) and fluid attenuated inversion recovery (FLAIR) image were significantly correlated with the tumor consistency (p = 0.004 and 0.045, respectively). The hypointense tumors on both MRI sequences tended to be hard, whereas the tumors showing hypersignal intensity were associated with soft consistency. There was no correlation between the consistency and age, gender, duration of neurologic symptoms, tumor location, size, calcification, cystic portion, en plague appearance, tumor-brain contact interface expressed by cerebrospinal fluid (CSF) cleft, perilesional vasogenic edema, bony status, features on T1-weighted image (T1WI) and pattern of contrast enhancement. In multiple logistic regression analysis, the tumor characteristics on T2WI and FLAIR image were independent factors significantly correlated with the tumor consistency (p = 0.005 and 0.041, respectively). The tumor consistency was also correlated with operative radicalness as evaluated by the Simpson criteria.

CONCLUSIONS

Signal intensity on T2WI and FLAIR image can be used for insinuating meningioma consistency. Presurgical prediction of the consistency is highly valuable in operative planning, particularly in arduous cases.

Differential diagnosis of jugular foramen lesions

The anatomy of the jugular foramen is complex. It contains the lower cranial nerves and major vascular structures. Tumors that develop within it, or extend into it, provide significant diagnostic and surgical challenges. In this article, we describe the anatomy of the jugular foramen and outline an imaging protocol that can differentiate between lesions, thereby aiding diagnosis and facilitating management.

Peritumoral brain edema in meningiomas : correlation of radiologic and pathologic features

OBJECTIVE

The primary objective of this study was to perform a retrospective evaluation of the radiological and pathological features influencing the formation of peritumoral brain edema (PTBE) in meningiomas.

METHODS

The magnetic resonance imaging (MRI) and pathology data for 86 patients with meningiomas, who underwent surgery at our institution between September 2003 and March 2009, were examined. We evaluated predictive factors related to peritumoral edema including gender, tumor volume, shape of tumor margin, presence of arachnoid plane, the signal intensity (SI) of the tumor in T2-weighted image (T2WI), the WHO histological classification (GI, GII/GIII) and the Ki-67 antigen labeling index (LI). The edema-tumor volume ratio was calculated as the edema index (EI) and was used to evaluate peritumoral edema.

RESULTS

Gender (p=0.809) and pathological finding (p=0.084) were not statistically significantly associated with peritumoral edema by univariate analysis. Tumor volume was not correlated with the volume of peritumoral edema. By univariate analysis, three radiological features, and one pathological finding, were associated with PTBE of statistical significance: shape of tumor margin (p=0.001), presence of arachnoid plane (p=0.001), high SI of tumor in T2WI (p=0.001), and Ki-67 antigen LI (p=0.049). These results suggest that irregular tumor margins, hyperintensity in T2WI, absence of arachnoid plane on the MRI, and high Ki-67 LI can be important predictive factors that influence the formation of peritumoral edema in meningiomas. By multivariate analysis, only SI of the tumor in T2WI was statistically significantly associated with peritumoral edema.

CONCLUSION

Results of this study indicate that irregular tumor margin, hyperintensity in T2WI, absence of arachnoid plane on the MRI, and high Ki-67 LI may be important predictive factors influencing the formation of peritumoral edema in meningiomas.

¹H-MRS of intracranial meningiomas: what it can add to known clinical and MRI predictors of the histopathological and biological characteristics of the tumor?

OBJECTIVE

The main goal of the present study was evaluation of proton magnetic resonance spectroscopy (¹H-MRS) in diagnosis of histopathologically aggressive intracranial meningiomas.

METHODS

Single-voxel ¹H-MRS of 100 intracranial meningiomas was performed before their surgical resection. Investigated metabolites included mobile lipids, lactate, alanine, N-acetylaspartate (NAA), and choline-containing compounds (Cho). According to criteria of World Health Organization (WHO) 82 meningiomas were assigned histopathological grade I, 11 grade II, and 7 grade III. The MIB-1 index varied from 0% to 27.3% (median, 1.6%). In 43 cases tight adhesion of the tumor to the pia mater or brain tissue was macroscopically identified at surgery. The consistency of 49 meningiomas was characterized as soft, 26 as hard, and 25 as mixed.

RESULTS

No one metabolic parameter had statistically significant association with histopathological grade and subtype, invasive growth, and consistency of meningioma. Univariate statistical analysis revealed greater ¹H-MRS-detected Cho content (P=0.0444) and lower normalized NAA/Cho ratio (P=0.0203) in tumors with MIB-1 index 5% and more. However, both parameters lost their statistical significance during evaluation in the multivariate model along with other clinical and radiological variables. It was revealed that non-benign histopathology of meningioma (WHO grade II/III) is mainly predicted by irregular shape (P=0.0076) and large size (P=0.0316), increased proliferative activity by irregular shape (P=0.0056), and macroscopically invasive growth by prominent peritumoral edema (P=0.0021).

CONCLUSION

While ¹H-MRS may be potentially used for the identification of meningiomas with high proliferative activity, it, seemingly, could not add substantial diagnostic information to other radiological predictors of malignancy in these tumors.

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.

METHOD

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.

FINDINGS

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.

Petroclival mixed meningioma

We present a 47-year-old lady with a large dumb-bell petroclival-cavernous sinus meningioma. The tumour was of mixed histopathology; the anterior part, in relationship to the cavernous sinus, was a syncitial meningioma and the posterior part in the petroclival region was a transitional meningioma. The two histological subtypes of meningioma within the same tumour displayed remarkable differences in their radiological features, nature of extensions, relationship with the adjoining structures and consistency. The clinical course of the two subtypes was also different. The unusual features of this case are reported and the relevant literature briefly reviewed.

Thallium-201 brain SPECT to diagnose aggressiveness of meningiomas

This investigation was conducted to determine the ability of 201Tl brain SPECT with respect to preoperative prediction of lesional aggressiveness of meningioma. Fifty-nine lesions in 42 patients were examined. Early (15 min) and late (3 h) SPECT were obtained. Early uptake ratio (ER; lesion to normal brain average count ratio), late uptake ratio (LR) and the ratio of LR to ER (L/E ratio) were calculated. Twenty-three lesions exhibited malignant features based on histologic or clinical course such as recurrence or skull invasion. Both ER and LR of malignant meningiomas were significantly higher than those in thirty-six benign lesions. Benign lesions were classified into two groups for further analysis: meningotheliomatous type, which is the most common histology, and benign lesions other than the meningotheliomatous (other benign) type. ER in other benign type was lower than the meningotheliomatous and the malignant type. LR afforded differentiation of the malignant type from the two benign types. These two benign types could be distinguished on the basis of the L/E ratio. These results indicate that high pre-operative ER and LR values in patients with meningioma are indicators of the aggressiveness of lesions, i.e., malignant meningioma, recurrence or skull invasion.

(1)H-MRS metabolic patterns for distinguishing between meningiomas and other brain tumors

Yet meningiomas have characteristic neuroimaging features, some other lesions are still confusing with meningiomas. The aim of this study was trying to find the typical (1)H-MRS metabolic factors of histologic subtyped meningiomas, schwannomas, metastases, and other brain tumors for differential diagnosis among them. (1)H-MRS using STEAM (TE/30 ms, TR/2 sec) and PRESS (TE/288 ms, TR/2 sec) sequences were performed on 44 untreated brain tumors. Obtained metabolic patterns from the typical spectra of meningioma, schwannoma, metastasis were compared with each other or other brain tumors to evaluate the usefulness for diagnosis between them. Alanine(Ala) was observed in 15 cases of the 19 meningiomas with a little variation to three histologic subtypes, while minimal lipids were observed in every 19 meningiomas. Elevated glutamate/glutamine(Glx) was detected in 12 cases of the meniningiomas. Increased myo-inositol(mI) was detected in 11 cases of the 13 schwannomas. Dominant lipids signals as well as long-T2 lipids were detected in every metastasis in conjunction with elevated choline (Cho). Enhanced Glx was observed in 4 cases of the 8 metastases without correlation of primary tumor site or types. Hemangiopericytoma showed different spectral patterns from typical meningiomas: only dominant Cho, minimal lipids and absence of Ala or Glx signals. These metabolic patterns in typical tumors may provide a basis for differential diagnosis (average value of chi(2) = 23.33, p < 0.01) between meningiomas and schwannomas as well as metastases. However proton spectral distinction among the different histologic subtypes of meningiomas was not definite.

Prediction of Tumor-brain Adhesion in Intracranial Meningiomas by MR Imaging and DSA

OBJECTIVES

The purpose of this study was to evaluate the usefulness of MRI (magnetic resonance imaging) and DSA (digital subtraction angiography) by using preoperative MRI and DSA findings in the examination of meningiomas before excision. In particular, we focused on their usefulness in predicting tumor-brain adhesion during surgery.

MATERIALS AND METHODS

The subjects were 36 patients with intracranial meningioma who underwent tumor excision at which time neurosurgeons examined the tumor-brain adhesion. Two neurosurgeons evaluated the degree of tumor-brain adhesion from operation records and videotapes recorded during surgery. Two neuroradiologists retrospectively evaluated the preoperative MRI findings including tumor diameter, signal intensity of the tumor parenchyma obtained with T(2)-weighted imaging (T(2)WI), characteristics of the tumor-brain interface, and degree of peritumoral brain edema. The vascular supply was also evaluated from the preoperative DSA findings. The relationship between these MRI and DSA findings and the degree of tumor-brain adhesion during surgery as classified by the neurosurgeons was statistically analyzed.

RESULTS

The degree of peritumoral brain edema and the shapes and characteristics of the tumor-brain interface, including the findings of FLAIR (fluid-attenuated inversion recovery) imaging and vascular supply observed by DSA, were significantly correlated with tumor-brain adhesion. In particular, the shapes and characteristics of the tumor-brain interface as observed by T(1)-weighted imaging (T(1)WI), T(2)WI, and FLAIR, respectively, as well as the vascular supply observed by DSA, were closely correlated with the degree of tumor-brain adhesion encountered during surgery. According to these results, we developed a method of predicting tumor-brain adhesion that considers the shape of the tumor-brain interface revealed by MRI and the vascular supply revealed by DSA.

CONCLUSIONS

We retrospectively examined the findings of MRI and DSA performed before excision of meningioma and clarified the relationship between the findings and tumor-brain adhesion. We speculated that tumor-brain adhesion can be accurately and simply predicted before surgery with a new method that considers the shape of the tumor-brain interface observed by MRI and vascular supply observed by DSA.

Meningiomas with brain edema: radiological characteristics on MRI and review of the literature

OBJECT

Despite their benign characteristics, meningiomas are often accompanied by perifocal brain edema. The aims of this study are to determine what kind of characteristics on magnetic resonance (MR) image are indicative of a meningioma that produces brain edema and to investigate the mechanism responsible for brain edema accompanying meningiomas.

METHODS

Fifty-one patients with meningioma were examined by magnetic resonance imaging (MRI), and tumor size, tumor location, shape of tumor margin, peritumoral rim, and signal intensity of tumor on T2-weighted image (T2WI) were compared and correlated with the presence versus absence of brain edema. Surgical histopathology was also examined and correlated with the MRI findings and brain edema.

RESULTS

Shape of tumor margin, peritumoral rim, and signal intensity of tumor on T2WI correlated with brain edema on multivariate analyses.

CONCLUSION

Invasive pattern of brain-tumor interface and hyperintensity on T2WI were indicative factors of meningiomas producing brain edema.

Peritumoral brain edema in intracranial meningiomas: effects of radiological and histological factors

OBJECTIVE

We examined the radiological and histological features influencing the development of peritumoral brain edema (PTBE) among patients with meningiomas.

METHODS

Factors causing PTBE were retrospectively analyzed for 125 patients with primary intracranial meningiomas. These factors included tumor size, tumor location, brain-tumor interface, signal intensity on T2-weighted scans, contrast enhancement, and cyst formation (as observed on magnetic resonance imaging scans), as well as tumor vascularity and blood supply (as observed in digital subtraction angiography studies). We defined the edema/tumor volume ratio as the edema index, and we used this index to evaluate PTBE.

RESULTS

A relationship between the tumor size and the volume of PTBE was observed. Convexity and middle fossa meningiomas demonstrated the greatest increases in mean edema indices. Meningothelial, anaplastic, microcystic, and angiomatous subtypes exhibited higher edema indices than did other types. Multivariate analysis demonstrated two significant radiological factors: cortical penetration (as defined by the disappearance of the arachnoid layer on magnetic resonance imaging scans) (relative risk, 2.067; P = 0.0148) and vascular supply from the pial-cortical arteries (as observed on angiograms) (relative risk, 2.087; P = 0.0082).

CONCLUSION

Tumor infiltration into adjacent brain parenchyma and a pial-cortical blood supply are critical factors for the development of PTBE among patients with meningiomas.

Secretory meningioma: clinicopathologic features of eight cases

The clinical and morphological features of eight patients with meningothelial meningiomas with numerous pseudopsammoma bodies (secretory meningiomas) are presented. The six female and two male patients ranged in age from 43 to 68 years. Tumours were located at the petroclival region in two, the lateral parasellar region in two, the petrous apex in one and the sphenoid ridge in three patients. On magnetic resonance imaging, they were iso or hypointense on T1-weighted images, and hyper or isointense on T 2-weighted images. Peritumoral brain edema was absent in five cases, and was mild to moderate in three cases. Serum carcinoembryonic antigen (CEA) levels were measured preoperatively in three patients, with one having an elevated serum CEA level which re turned to normal following tumour resection. Immunohistochemical analysis on the resected tumour tissues, pseudopsammoma bodies and surrounding tumour cells were shown to be CEA-positive. Ultrastructurally, pseudopsammoma bodies were composed of granular and filamentous materials located predominantly in the intracellular lumina, which were lined by microvilli. While these morphological features of focal epithelial and secretory differentiation of tumour cells call attention to the broad spectrum of differentiation properties of meningiomas, the biological behavior of the eight tumours reported herein corresponded to those of meningiomas in general.

Correlation of the relationships of brain-tumor interfaces, magnetic resonance imaging, and angiographic findings to predict cleavage of meningiomas

OBJECT

The authors examined the relationships of brain-tumor interfaces, specific magnetic resonance (MR) imaging features, and angiographic findings in meningiomas to predict tumor cleavage and difficulty of resection.

METHODS

Magnetic resonance imaging studies, angiographic data, operative reports, clinical data, and histopathological findings were examined retrospectively in this series, which included 126 patients with intracranial meningiomas who underwent operations in which microsurgical techniques were used. The authors have identified three kinds of brain-tumor interfaces characterized by various difficulties in microsurgical dissection: smooth type, intermediate type, and invasive type. The signal intensity on T1-weighted MR images was very similar regardless of the type of brain-tumor interface (p > 0.1). However, on T2-weighted images the different interfaces seemed to correlate very precisely with the signal intensity and the amount of peritumoral edema (p < 0.01), allowing the prediction of microsurgical effort required during surgery. On angiographic studies, the pial-cortical arterial supply was seen to participate almost equally with the meningeal-dural arterial supply in vascularizing the tumor in 57.9% of patients. Meningiomas demonstrating hypervascularization on angiography, particularly those fed by the pial-cortical arteries, exhibited significantly more severe edema compared with those supplied only from meningeal arteries (p < 0.01). Indeed, a positive correlation was found between the vascular supply from pial-cortical arteries and the type of cleavage (p < 0.05).

CONCLUSIONS

In this analysis the authors proved that there is a strong correlation between the amount of peritumoral edema, hyperintensity of the tumor on T2-weighted images, cortical penetration, vascular supply from pial-cortical arteries, and cleavage of the meningioma. Therefore, the consequent difficulty of microsurgical dissection can be predicted preoperatively by analyzing MR imaging and angiographic studies.

Intracranial meningiomas: correlations between MR imaging and histology

The authors have examined the relationship between magnetic resonance imaging (MRI) and histopathological features in 35 surgically verified intracranial meningiomas. Tumor signals on T1-weighted images were rather similar regardless of the histologic subtype of the tumors. On T2-weighted images, hypointense meningiomas were mainly fibroblastic and hyperintense tumors were mainly syncytial and angioblastic, and partly transitional. Isointense tumors were mainly transitional and partly fibroblastic and syncytial. The authors conclude that the signal intensity of the MRI may be useful in the preoperative characterization of intracranial meningiomas. T1-weighted images may predict the presence of cysts and intratumoral blood vessels; whereas T2-weighted images can give information about histological subtype, vascularity and consistency. Meningiomas hyperintense to the cortex on T2 are usually soft, more vascular and more frequently of syncytial or angioblastic subtype; tumors hypointense or hypo-isointense on T2 tend to have a more hard consistency and are more often of fibroblastic or transitional subtype.

Solitary meningeal plasmacytomas

BACKGROUND

Solitary extramedullary plasmacytoma (SEP) represents a rare separate clinical pathological entity; it is radiosensitive, curable, and unrelated to myeloma. Only 15 cases have been reported.

PATIENTS AND METHODS

Authors report two well documented cases of dural plasmocytomas mimicking meningiomas. This paper points out differences between plasmacytomas, with very different initial presentation, and other meningeal tumors including extensive radiological investigations. Diagnostic options and outcomes are discussed.

CONCLUSION

With solitary plasmacytomas, radiological diagnosis is difficult to assess. Serum is generally free of monoclonal protein. The importance of the most recent techniques in ruling out other pathological entities is stressed. Histopathological examination is required to document a monoclonal type of plasma cell tumor. Treatment includes surgery and radiotherapy. Differential radiological diagnosis will be discussed.

Brain edema in meningiomas is associated with increased vascular endothelial growth factor expression

OBJECTIVE

Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF), an endothelial cell-specific cytokine, induces proliferation of endothelial cells and increases vascular permeability dramatically. All gliomas secrete significant amounts of VEGF, whereas meningiomas are variable in expression. Thus, we sought to determine whether the extent of VPF/VEGF expression in meningiomas correlated with differences in brain edema associated with these tumors.

METHODS

Meningioma tissue samples from 37 patients (15 men, average age 65 +/- 13 yr; 22 women, average age 60 +/- 10 yr) who underwent surgery at or were referred to the University of Alabama Hospital were examined retrospectively for the extent of expression of immunoreactive VPF/VEGF. Additionally, peritumoral edema was assessed on a blinded basis radiographically from preoperative magnetic resonance imaging scans. Selected specimens were examined by in situ hybridization to document the source of VPF/VEGF.

RESULTS

The predominant meningioma subclassifications were transitional (57%) or meningothelial (27%) subtypes. VPF/VEGF immunoreactivity ranged from 0 to 3.5, with a median value of 2 on a subjective 5-point scale; magnetic resonance imaging-assessed edema ranged in extent from 0 to 4 (subjective 5-point scale), with a median value of 2.5. The correlation of determination (R2) of magnetic resonance imaging-assessed tumor edema rating and VPF/VEGF staining intensity rating was 0.6087 (r = 0.78; P = 0.0001). In situ hybridization localized VPF/VEGF messenger ribonucleic acid in meningioma cells and not in normal parenchymal brain cells.

CONCLUSION

These data suggest that meningioma-associated edema may be a result of the capacity of meningioma cells to produce VPF/VEGF locally, leading to increased tumor neovascularization and enhanced vascular permeability.

A review of the radiological features of intracranial meningiomas

To evaluate the role of radiological imaging of meningiomas in confirming the diagnosis and as a neuroanatomical aid to surgical planning, 115 patients with surgically excised meningiomas between 1990 and 1993 were studied. Computed tomography (CT), magnetic resonance imaging (MRI) (on a 0.5 T unit) and angiography were reviewed, and compared with histopathology (when available). Seventy-eight CT, 89 MRI and 85 angiographic studies were reviewed, and correlated with histopathology in 67 cases. In 48 cases, the surgical specimens could not be pathologically classified. The most common lesion sites were the cerebral convexities, falx and sphenoidal ridges. True demarcation of cleavage planes was seen on 73% of MRI and 10% of CT studies. Computed tomography showed hyperostosis in 27% and MRI in 7% of studies. Tumours enhanced strongly with contrast in 98% of CT scans. On MRI there were variable signal intensities on different sequences, and no correlation between signal intensities and histological subtype was found. Oedema was present in 59% of CT and 66% of MRI studies, and was most pronounced in lesions > 3 cm in diameter. Tumour calcification was seen in 62% of CT and 8% of MRI studies. Vascular abnormalities were seen on 65% of MRI, 21% of CT and 84% of angiogram studies. Angiographic tumour vascularity did not correlate with histologic subtype. All three imaging modalities have management roles: CT for bony changes and calcification, MRI for multiplanar and vessel anatomy imaging, and angiography for vessel delineation and embolization if required.

Different thallium-201 single-photon emission tomographic patterns in benign and aggressive meningiomas

To evaluate the possibility of preoperatively obtaining an index of aggressiveness for intracranial meningiomas, we prospectively studied 22 patients with computed tomographic or magnetic resonance imaging evidence of meningeal tumour, using single-photon emission tomography (SPET) of the brain and thallium-201 (201Tl). On a brain-dedicated SPET scanner, a rapid acquisition protocol with early, short scans was started simultaneously with the intravenous administration of 111 MBq 201Tl, covering the initial intratumoral distribution of the tracer. Twenty minutes post injection, a delayed SPET scan was also obtained. On the reconstructed and attenuation-corrected images we calculated the 201Tl concentration in tumour and normal contralateral brain tissue, and compared intratumoral tracer concentration in the initial and the final part of the rapid acquisition protocol. Benign and malignant meningiomas were classified as such based on histological examination. In malignant lesions, the ratio of the 201Tl concentration at 2-4 min post injection to that at 14-16 min was found to be significantly higher than in non-aggressive neoplasms (mean+/-1 SD: 1.14+/-0.31 and 0.56+/-0.13, respectively, P <0.01). Conversely, in the delayed scan, most lesions showed high tracer concentration, and the two groups could not be distinguished. In addition, three recurrent meningiomas displayed the same imaging behaviour as the malignant group, i.e. had similar 201Tl concentration values at 2-4 and at 14-16 min. Our findings suggest that the comparative assessment of intratumoral 201Tl concentration at 2-4 and at 14-16 min post injection could provide a fast, simple method to differentiate preoperatively intracranial meningiomas with different biological behaviour.

Meningioma: proliferating potential and clinicoradiological features

We examined the proliferative potentials of meningiomas in 120 patients using the MIB-1 antibody against the Ki-67 antigen and compared them with the clinicoradiological features. The Ki-67 staining index (SI) did not relate to the age and sex of the patients or the location of the tumors. Asymptomatic meningiomas showed significantly lower SIs (mean +/- standard deviation [SD], 0.87 +/- 0.56%) than symptomatic meningiomas (mean +/- SD, 1.63 +/- 2.17%). We found no relation between SIs and clinical symptoms and signs in the symptomatic meningiomas. A weak correlation was found between the size of tumors and Ki-67 SIs (r = 0.21; P = 0.024). There were significant differences in SIs between calcified (mean +/- SD, 0.77 +/- 0.41%) and noncalcified tumor (mean +/- SD, 1.75 +/- 2.25%). Diffusely calcified tumors (mean +/- SD, 0.57 +/- 0.34%) showed lower SIs than focally calcified tumors (mean +/- SD, 0.92 +/- 0.41%). Lobulated tumors showed higher SIs (mean +/- SD, 2.85 +/- 3.68%) than round tumors (mean +/- SD, 1.06 +/- 0.67%). Tumors with perifocal edema or unclear borders had higher SIs than did those without such features. Signal intensities on T1-weighted magnetic resonance images had no relation to SIs, whereas low-intensity tumors on T2-weighted images, most of which presented diffuse calcification on computed tomographic scans, showed lower SIs. This study indicates that several clinicoradiological features relate to the proliferative potential of meningiomas and that they may contribute to the management of patients.

Aggressive meningeal tumors: review of a series

A series of 25 patients with aggressive meningeal tumors was studied to determine the efficacy of various management options. The median age of the patients was 52 years, with a range of 13 to 73 years. A marked male preponderance (64%) was noted. Twenty of 25 patients experienced recurrence during a median follow-up time of 47 months. Survival and freedom from recurrence varied with histological diagnosis. Recurrence was noted sooner in patients who had received partial resections on first presentation of tumor than in those who had received total resections at first presentation. Survival time was also shorter for patients who underwent partial resections at first presentation than for patients who underwent total resections. Patients' prognoses did not improve as a result of either chemotherapy or radiotherapy. Of six patients with extracranial metastases, the median time to metastasis was 102 months, with a 5-year metastasis-free rate of 85%. The most common sites of metastasis in these six patients were lung and bone. In each tumor type, histological features used in diagnosis and radiological features studied from computerized tomography and magnetic resonance imaging were evaluated, compared, and discussed. Of eight patients studied with an in vivo bromodeoxyuridine (BUdR) labeling index (LI), seven showed an LI of 1% or more. The authors support the incorporation of the BUdR LI into the diagnostic process to provide a better estimate of the potential for tumor recurrence.

Neuroimaging of meningeal disease

In the past two decades, the advent of CT and MRI has made a considerable impact on the evaluation of meningeal diseases, conditions once regulated to cytological, histopathological, or postmortem analyses alone. This article reviews the imaging findings in various meningeal processes with particular attention to the anatomic definition of the meningeal layers and their relationship to the development of meningeal pathology and consequent imaging characteristics.

Meningiomas: correlation between MRI characteristics and operative findings including consistency

The findings on magnetic resonance imaging (MRI) in 73 surgically verified intracranial meningiomas were correlated with their histology and consistency during resection. T 1-weighted imaging was least useful since most of the tumours were iso-intense, similar to cortical grey matter regardless of histology or tumour consistency. The signal intensity on T2-weighted images was found to best correlate with both the histology and consistency of the meningioma. Generally, the low intensity portion of the tumour on T2-weighted images indicated a more fibrous and harder character, while the higher intensity portions indicated a more soft character. Most of the fibroblastic meningiomas showed the features of a hard tumour while angioblastic tumours showed the features of soft tumours. Tumours predicted to be harder on MR imaging generally took longer to resect than softer ones, and this relationship was shown best for the larger tumours. Using linear regression analysis, it appears that operative time for soft tumours is more affected by factors other than tumour consistency. Blood loss during surgery was also unrelated to the consistency of the tumour. These results suggest that the histology and consistency of meningiomas may be predictable from findings on T2-weighted imaging, and this may also predict the difficulty and time required for resection.

Magnetic resonance imaging and pathological correlates of meningiomas

We examined the relationships between specific magnetic resonance imaging features and certain gross and microscopic characteristics of meningiomas, including vascularity, gross texture (consistency), and venous sinus involvement. Magnetic resonance imaging scans, surgery reports, and the histopathological findings of tumors were examined retrospectively in 54 patients. Sinus involvement was accurately predicted on T1-weighted images in 9 of 10 cases (P = 0.001) and tumors with cystic changes in 3 of 3 cases. T1-weighted images were not useful for predicting vascularity unless actual flow voids could be visualized (five of six cases). There was no correlation between T1 signal intensity, tumor consistency, or histological findings. In tumors without detectable vascularity on T1-weighted images, hyperintensity relative to gray matter on T2-weighted images was correlated with increased vascularity (P = 0.004). Tumors with soft consistency (P = 0.007), cellular atypia, invasion, angioblastic, or melanocytic components were also hyperintense, compared with gray matter on T2-weighted images (P = 0.0266). Aggressive meningiomas were found to be more vascular (P = 0.045). No correlation was found between the degree of surrounding edema or contrast enhancement with histopathological findings, vascularity, or consistency.