Volumetric measurement of intracranial meningiomas: a comparison between linear, planimetric, and machine learning with multiparametric voxel-based morphometry methods.

PURPOSE: To compare the accuracy of three volumetric methods in the radiological assessment of meningiomas: linear (ABC/2), planimetric, and multiparametric machine learning-based semiautomated voxel-based morphometry (VBM), and to investigate the relevance of tumor shape in volumetric error. METHODS: Retrospective imaging database analysis at the authors' institutions. We included patients with a confirmed diagnosis of meningioma and preoperative cranial magnetic resonance imaging eligible for volumetric analyses. After tumor segmentation, images underwent automated computation of shape properties such as sphericity, roundness, flatness, and elongation. RESULTS: Sixty-nine patients (85 tumors) were included. Tumor volumes were significantly different using linear (13.82 cm3 [range 0.13-163.74 cm3]), planimetric (11.66 cm3 [range 0.17-196.2 cm3]) and VBM methods (10.24 cm3 [range 0.17-190.32 cm3]) (p < 0.001). Median volume and percentage errors between the planimetric and linear methods and the VBM method were 1.08 cm3 and 11.61%, and 0.23 cm3 and 5.5%, respectively. Planimetry and linear methods overestimated the actual volume in 79% and 63% of the patients, respectively. Correlation studies showed excellent reliability and volumetric agreement between manual- and computer-based methods. Larger and flatter tumors had greater accuracy on planimetry, whereas less rounded tumors contributed negatively to the accuracy of the linear method. CONCLUSION: Semiautomated VBM volumetry for meningiomas is not influenced by tumor shape properties, whereas planimetry and linear methods tend to overestimate tumor volume. Furthermore, it is necessary to consider tumor roundness prior to linear measurement so as to choose the most appropriate method for each patient on an individual basis.

Central nervous system high-grade neuroepithelial tumor with BCOR alteration (CNS HGNET-BCOR)-case-based reviews.

INTRODUCTION: High-grade neuroepithelial tumor with BCOR alteration (HGNET BCOR) has been recently classified as a new category of tumors among those previously known as PNET. They are molecularly characterized by the mutation of the BCOR gene, a corepressor of BCL6 a gene (which has an important role in immune responses). Only case reports and very small series have been published so far; therefore, their behavior and management are still under investigation. The goal of the present case-based review is to provide a summary about the state of the art on these tumors. METHODS AND RESULTS: The pertinent review has been reviewed, and an exemplary case has been reported (15-month-old boy with large HGNET BCOR of the left cerebellopontine angle). So far, 24 cases have been described, with a 5.5 mean age at diagnosis and a 1.4 male/female ratio. The cerebellar hemisphere is the more frequently involved region. No metastases are usually detected at diagnosis, though they are common in case of tumor recurrence. There are no specific radiological or pathological features to differentiate HGNET BCOR from other brain malignant neuroepithelial tumors so that the differential diagnosis is obtained by DNA methylation profiling. The management possibly relies on surgery and (high dose) chemotherapy and radiotherapy but without a dedicated protocol yet. The overall survival after 48-month follow-up is 50%. A gross total resection, which is mandatory for a better outcome, is achievable in the majority of cases. CONCLUSIONS: The clinical research on HGNET BCOR is just at the beginning. New targets and wide-ranging clinical trials are needed to get an optimal management.

Endoscopic Endonasal Approach to Foramen Magnum Meningioma: Two-Dimensional Surgical Video.

Even for the most experienced neurosurgeons, foramen magnum meningiomas represent a surgical challenge owing to their delicate position surrounded by the brainstem, lower cranial nerves, and vertebral arteries. The treatment goal is gross total resection, but choosing the most appropriate approach is crucial. Basically, 3 surgical approaches are commonly used: posterolateral approach (far-lateral), anterolateral approach (extreme-lateral), and posterior midline approach. However, over the years, skull base surgery has evolved from standard open craniotomies to the use of microscopes and, more recently, to the development of endoscopic techniques. The endoscopic endonasal approach (EEA) permits a direct extradural route without brain retraction and shorter postoperative recovery. In contrast to the oral route, the soft palate and retropharyngeal soft tissues are preserved, allowing patients to resume a regular diet on the first postoperative day. Despite the advantages, the EEA is yet not widely used for treating foramen magnum meningiomas, even in cases where EEA use is possible. The EEA is feasible especially in cases with no vascular encasements and with a limited inferior extension allowing minimal manipulation of lower cranial nerves. Care must be taken with tumors with a more lateral and caudal extension (below the tip of the odontoid process), when a far lateral approach may be the best approach. In this surgical Video 1, we present the surgical details with a stepwise narrative of the EEA for ventrolateral foramen magnum meningiomas through an illustrative case of a 48-year-old woman. Institutional informed consent was obtained for surgery and publication of this video.