|Year : 2014 | Volume
| Issue : 2 | Page : 387-389
An atypical meningioma demystified and advanced magnetic resonance imaging techniques
Despoina Voultsinou1, Georgios K Matis2, Olga I Chrysou3, Theodossios A Birbilis3, Angeliki Cheva4, Triantafillos Geroukis1
1 Department of Radiology, General Hospital of Thessaloniki "G. Papanikolaou", Thessaloniki, Greece
2 Department of Neuroradiology, University Hospital of Zürich, Zürich, Switzerland
3 Department of Neurosurgery, Democritus University of Thrace Medical School, Alexandroupolis, Greece
4 Department of Pathology, General Hospital of Thessaloniki "G. Papanikolaou", Thessaloniki, Greece
|Date of Web Publication||14-Jul-2014|
Georgios K Matis
10 Plattenstrasse, Room 1401, CH-8032, Zürich
Source of Support: None, Conflict of Interest: None
A 40-year-old male presented with visuospatial processing disturbances. Family history was free. Conventional and advanced magnetic resonance imaging (MRI) studies were performed. On T2 and fluid attenuation inversion recovery images, an increased signal intensity extra-axial lesion was demonstrated. Post-contrast scans depicted homogeneous intense contrast medium enhancement. T2* star sequence was negative for hemorrhagic or calcification foci. Diffusion-weighted imaging findings were indicative of malignant behavior and magnetic resonance venography confirmed superior sagittal sinus infiltration. Increased cerebral blood volume values were observed and peri-lesional oedema on perfusion-weighted imaging was also demonstrated. The signal intensity-time curve depicted the characteristic meningioma pattern. Spectroscopy showed increased choline and alanine levels, but decreased N-acetyl-aspartate levels. Conventional MRI is adequate for typical types of meningiomas. However, the more atypical ones, in which even the histopathologic specimen may demonstrate characteristics of typical meningioma, could be easier diagnosed with advanced MRI techniques.
Keywords: Atypical meningioma, diffusion-weighted imaging, functional magnetic resonance imaging, magnetic resonance venography, magnetic resonance spectroscopy, perfusion-weighted imaging
|How to cite this article:|
Voultsinou D, Matis GK, Chrysou OI, Birbilis TA, Cheva A, Geroukis T. An atypical meningioma demystified and advanced magnetic resonance imaging techniques. J Can Res Ther 2014;10:387-9
|How to cite this URL:|
Voultsinou D, Matis GK, Chrysou OI, Birbilis TA, Cheva A, Geroukis T. An atypical meningioma demystified and advanced magnetic resonance imaging techniques. J Can Res Ther [serial online] 2014 [cited 2019 Nov 20];10:387-9. Available from: http://www.cancerjournal.net/text.asp?2014/10/2/387/136666
| > Introduction|| |
Although conventional magnetic resonance imaging (MRI) is adequate for characterisation of typical types of meningiomas, this technique alone may not be sufficient for the more atypical types. , In such cases, advanced MRI techniques are important supplemental means in the diagnosis of meningiomas. ,
Diffusion-weighted imaging and perfusion-weighted imaging (DWI, PWI) are advanced techniques that provide insights into the tumor behavior. ,,,,, DWI allows the cellularity of the tumour to be graded in a non-invasive manner, ,,,, and PWI gives a quantitative estimation of cerebral blood volume (CBV) that reflects the underlying microvasculature and angiogenesis.  Moreover, magnetic resonance venography (MRV) depicts possible sinus involvement,  and magnetic resonance spectroscopy (MRS) assesses the metabolic consistency of the meningioma.  The authors herein present a case of an atypical meningioma and underline the significant contribution of modern MRI techniques in setting the correct diagnosis.
| > Case report|| |
A 40-year-old male presented complaining for memory problems, inability to recognize familiar faces, and blurred vision. The neurological examination was normal. The conventional MRI protocol included: Axial non-enhanced T1-and T2-weighted sequences as well as fluid attenuation inversion recovery (FLAIR) and contrast-enhanced T1-weighted sequences. Additionally, single-shot-echo planar images were obtained (b-values: 0, 500, 1000 mm 2 /s). Apparent diffusion coefficient (ADC) maps were also generated. PWI with CBV mapping, MRV and MRS were also performed. On T2 and FLAIR images, an increased signal intensity extra-axial lesion was demonstrated [Figure 1]a and b. No perifocal oedema was observed. The signal intensity of the meningioma was similar to the brain parenchyma on T1-weighted images. Post-contrast scans demonstrated a homogeneous intense enhancement [Figure 1]c-e. T2* star sequence was negative for hemorrhagic or calcification foci. DWI demonstrated increased signal intensity and decreased ADC values of 0.541 × 10−3 mm 2 /s without calcification foci on T1 and T2* images. The findings were indicative of malignant behavior [Figure 2]a. Increased CBV values were observed at the perilesional oedema on PWI, with regional cerebral blood volume (rCBV) values of 5.8% [Figure 2]b. The signal intensity-time curve depicted the characteristic "mother in law" pattern of enhancement [Figure 2]c. MRS showed increased choline and alanine levels, and decreased N-acetyl-aspartate (NAA) levels. Infiltration of the superior sagittal sinus with lumen stenosis at the adhesion point was demonstrated on MRV [Figure 3]a and b.
|Figure 1: A 40-year-old man with a histologically verified meningioma. (a) Axial T2-weighted image visualized an extra-axial broad based parietal lobe lesion, isointense to brain parenchyma. There was a minimal mass effect. (b) Axial fluid attenuation inversion recovery-weighted image showed analogous findings. (c) Post-contrast T1 MRI scan demonstrated an extra-axial mass with a dural tail sign and intense homogeneous enhancement (axial view). (d) Sagittal post-contrast T1-image. (e) Coronal post-contrast T1-image|
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|Figure 2: Same patient. (a) Diffusion-weighted image demonstrating decreased apparent diffusion coefficient values on apparent diffusion coefficient ADC map. (b) Perfusion-weighted image showing increased regional cerebral blood volume values. (c) Signal intensity-time curve displaying immediate leakage of contrast media due to absence of blood brain barrier which is characteristic of extra-axial tumours, followed by partial and slow recovery of signal intensity ("mother in law" sign)|
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|Figure 3: (a) Magnetic resonance venography imaging (sagittal view). (b) Magnetic resonance venography imaging (coronal view). Magnetic resonance venography depicted infiltration of the superior sagittal sinus and lumen stenosis at the adhesion point|
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The possible diagnosis of an atypical meningioma was set, which was later confirmed histopathologically after the total tumor's resection; large uniform cells with oval to round nuclei with delicate chromatin forming lobules. Mitoses were very few and no necroses were seen [Figure 4]a. The neoplastic cells were positive to vimentin and epithelial membrane antigen. The ki-67 proliferation index was 5% [Figure 4]b.
|Figure 4: (a) The neoplastic cells expressed vimentin and epithelial membrane antigen (magnification ×400). (b) Proliferation index ki-67 was about 5% (magnification ×200)|
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Post-operatively, the patient quickly improved. One year later he remains symptom-free.
| > Discussion|| |
The diagnosis of typical meningiomas with the aid of computed tomography is easy. ,,, Typically, they present as intensely enhancing extra-axial masses. In atypical cases, meningiomas may include a cystic part, fatty transformation or an "en plaque" morphology. The "dural tail" sign is a dural thickening due to either meningeal infiltration or reactive reaction. , It is not a specific imaging sign and it is present only in 65% of meningiomas. It is seen in several other cases, such as chloroma, lymphoma, sarcoidosis, acoustic neurinoma and dural tail metastasis. ,, Additionally, meningiomas have been described not only with peripheral contrast enhancement but also with complete absence in 15-35% of cases. ,
Atypical meningiomas may coexist with cystic and hemorrhagic parts, as well as with a peripheral pattern of enhancement and may mimic a peripheral enhancing mass lesion (glioblastoma multiforme, solitary metastasis, brain abscess). ,,, The increased signal intensity on T2-images is more frequently observed in aggressive meningiomas and corresponds to masses of soft consistency and/or increased vascularity. Decreased signal intensity is linked with the presence of fibrous tissue.
DWI allows the cellularity of meningiomas to be graded non-invasively because cells constitute a relative barrier to water diffusion as compared with extracellular space. ,,,,, Typical meningiomas demonstrate the variable signal intensity on DWI with increased signal intensity on ADC maps and increased ADC values, with the exception of the calcified psammomatous bodies that form an irregular calcified mass with decreased ADC values. Tumour with greater cellularity show increased signal intensity on DWI with low ADC values. Malignant meningiomas demonstrate increased signal intensity on DWI with very low signal intensity on ADC maps, and extremely low ADC values indicative of marked diffusion (exception: the cystic or necrotic part of the lesion, which has increased ADC values).
The degree of angiogenesis is a key determinant of malignant potential in brain tumors.  Although conventional MRI with gadolinium is useful for tumor detection and characterisation, this enhancement reflects the disruption of the blood brain barrier rather than the vascularity.  PWI offers the quantitative estimation of CBV that reflects the underlying microvasculature and angiogenesis.  Given the correlation of micro-vessel density and tumour grade and the further correlation between micro-vessel density and CBV, higher-grade meningiomas demonstrate higher CBV values. , Since meningiomas are intensively vascular lesions with absolute absence of blood brain barrier, the conditions for proper measurements of rCBV values are violated by definition. , The correction of hypo- or hyper-estimation that comes from the serious contrast medium leakage through the interstitial space is not possible. , Of note, the signal intensity-time curve of meningiomas displays an immediate leakage of contrast media due to absence of blood brain barrier; this is characteristic of extra-axial tumors, and it is followed by a partial and slow recovery of signal intensity known as the "mother in-law" sign. ,,
MRV evaluates the possible sinus involvement, and MRS shows increased alanine levels with peaks ranging between 1.3 ppm and 1.15 ppm.  NAA and creatine levels are virtually zero. Lipids might be demonstrated. Functional MRI could serve as a preoperative map.
Predicting the histological nature of meningiomas could assist treatment-planning. In cases of inadequate sampling, the histological documentation may lead to a misleading diagnosis. It is in such cases that the aid of advanced MR techniques is invaluable in order to improve patients' outcome.
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