Gabrielle A. Yeaney

MR diffusion tensor and perfusion-weighted imaging in preoperative grading of supratentorial nonenhancing gliomas

We evaluate the value of MR diffusion tensor imaging (DTI) and dynamic susceptibility-weighted contrast material-enhanced perfusion-weighted imaging (PWI) in preoperative grading of supratentorial nonenhancing gliomas. This institutional review board-approved, Health Insurance Portability and Accountability Act-compliant retrospective study involved 52 patients: 37 with low-grade gliomas (LGGs) and 15 with high-grade gliomas (HGGs). The mean trace apparent diffusion coefficient (ADC), minimal ADC, mean fractional anisotropy (FA), maximal FA, and maximal relative cerebral blood volume (rCBV) ratio of the lesions were measured and compared between LGG and HGG. The efficacy of the above parameters in grading supratentorial nonenhancing gliomas was evaluated. There was no significant difference in rCBV ratio, minimal ADC, and mean ADC between LGG and HGG (p > 0.05). The mean and maximal FA values of LGG were significantly lower than the values of HGG (p < 0.001). The receiver operating characteristic analysis showed that the mean FA with a cutoff value of 0.129 and the maximal FA with a cutoff value of 0.219 could differentiate between LGG and HGG with specificity of 69.2% and 76.9%, respectively, and sensitivity of 93.3% and 100.0%, respectively. The combination of mean FA and maximal FA based on the linear discriminant analysis improved the diagnostic accuracy with specificity of 92.3% and sensitivity of 86.7%. These findings were better than maximal rCBV ratio, mean ADC, and minimum ADC. The mean FA and maximal FA, used individually or combined, may be useful in preoperative grading of supratentorial nonenhancing gliomas.

Isocitrate dehydrogenase 1 analysis differentiates gangliogliomas from infiltrative gliomas.

Recent work has identified novel point mutations in isocitrate dehydrogenase 1 (IDH1) in the majority of the World Health Organization grades II and III infiltrative gliomas and secondary grade IV glioblastomas. Gangliogliomas consist of neoplastic ganglion and glial cells and, in contrast to infiltrative gliomas, are generally indolent. Yet distinguishing between a ganglioglioma and an infiltrative glioma with admixed gray matter can be difficult, perhaps accounting for some “gangliogliomas” that ultimately show aggressive behavior. In this multi‐institutional study, 98 cases originally diagnosed as ganglioglioma were analyzed for IDH1 mutations, 86 of which had follow‐up data available. Eight cases (8.2%) were positive for R132H IDH1 mutations; six had silent IDH2 mutations and two had nonsense IDH2 mutations. The presence of mutant IDH1 in gangliogliomas correlated with a greater risk of recurrence (P = 0.0007) and malignant transformation and/or death (P < 0.0001) compared with tumors that were IDH1 wild type. Furthermore, the age of patients with IDH1‐mutant gangliogliomas was higher than those without mutations (25.5 vs. 46.1 years, P = 0.0033). IDH1/2 testing of tumors suspected of being gangliogliomas may therefore be advisable, particularly in the adult population.

Expanded endoscopic endonasal resection of an olfactory schwannoma

Olfactory schwannomas are rare tumors of the anterior skull base that are possibly derived from ectopic Schwann cells, perivascular neural tissue, or sensory nerves of the meninges. The authors report the case of a 14-year-old boy with an olfactory schwannoma that extended inferiorly through the cranial base and superiorly into the frontal lobe. Because of the growth characteristics of the tumor and the significant overlying frontal lobe edema, the lesion was approached via an endonasal endoscopic route, as a strategy to minimize brain retraction. This tumor was characterized radiographically as contrast-enhancing with cystic areas and erosion into bone. The tumor showed immunoreactivity for S100 protein and leukocyte antigen 7 (CD57) but not epithelial membrane antigen, supporting the diagnosis of olfactory schwannoma. A gross-total resection was achieved. This approach represents a novel application of endoscopic endonasal surgery to the pediatric neurosurgical context, as well as a favorable outcome in an extremely unusual tumor type, that should be applicable to other appropriately selected pediatric brain tumors.

Correlation of Diffusion and Perfusion MRI With Ki-67 in High-Grade Meningiomas

OBJECTIVE Atypical and anaplastic meningiomas have a greater likelihood of recurrence than benign meningiomas. The risk for recurrence is often estimated using the Ki-67 labeling index. The purpose of this study was to determine the correlation between Ki-67 and regional cerebral blood volume (rCBV) and between Ki-67 and apparent diffusion coefficient (ADC) in atypical and anaplastic meningiomas. MATERIALS AND METHODS A retrospective review of the advanced imaging and immunohistochemical characteristics of atypical and anaplastic meningiomas was performed. The relative minimum ADC, relative maximum rCBV, and specimen Ki-67 index were measured. Pearsons correlation was used to compare these parameters. RESULTS There were 23 cases with available ADC maps and 20 cases with available rCBV maps. The average Ki-67 among the cases with ADC maps and rCBV maps was 17.6% (range, 5-38%) and 16.7% (range, 3-38%), respectively. The mean minimum ADC ratio was 0.91 (SD, 0.26) and the mean maximum rCBV ratio was 22.5 (SD, 7.9). There was a significant positive correlation between maximum rCBV and Ki-67 (Pearsons correlation, 0.69; p = 0.00038). However, there was no significant correlation between minimum ADC and Ki-67 (Pearsons correlation, -0.051; p = 0.70). CONCLUSION Maximum rCBV correlated significantly with Ki-67 in high-grade meningiomas.

Case 163: Solitary Neurocysticercosis

While a parenchymal cysticercal lesion in the brain may cause a diagnostic dilemma, radiologic features correlate with pathologic findings and can aid in the diagnosis of solitary cerebral neurocysticercosis.

Correlation between Dynamic Contrast-enhanced Perfusion MRI Relative Cerebral Blood Volume and Vascular Endothelial Growth Factor Expression in Meningiomas

PURPOSE To determine whether there is a correlation between vascular endothelial growth factor (VEGF) expression and cerebral blood flow (CBV) measurements in dynamic contrast-enhanced susceptibility perfusion magnetic resonance imaging (MRI) and to correlate the perfusion characteristics in high- versus low-grade meningiomas. METHODS AND MATERIALS A total of 48 (24 high-grade and 24 low-grade) meningiomas with available dynamic susceptibility-weighted MRI were retrospectively reviewed for maximum CBV and semiquantitative VEGF immunoreactivity. Correlation between normalized CBV and VEGF was made using the Spearman rank test and comparison between CBV in high- versus low-grade meningiomas was made using the Wilcoxon test. RESULTS There was a significant (P = .01) correlation between normalized maximum CBV and VEGF scores with a Spearman correlation coefficient of 0.37. In addition, there was a significant (P < .01) difference in normalized maximum CBV ratios between high-grade meningiomas (mean 12.6; standard deviation 5.2) and low-grade meningiomas (mean 8.2; standard deviation 5.2). CONCLUSION The data suggest that CBV accurately reflects VEGF expression and tumor grade in meningiomas. Perfusion-weighted MRI can potentially serve as a useful biomarker for meningiomas, pending prospective studies.

SWAN MRI revealing multiple microhemorrhages secondary to septic emboli from mucormycosis

A 77-year-old man with myelodysplastic syndrome presented with fever and acute renal failure, followed by right-sided hemiparesis, neglect, and aphasia. Neuroimaging revealed a left parietal-occipital ICH with extensive edema. T2-star susceptibility weighted angiography (SWAN) revealed multiple

Diffusion-weighted imaging of skull lesions.

Diffusion-weighted imaging can increase the conspicuity of skull lesions and be applied toward noninvasive differentiation of malignant from benign lesions. Malignant skull lesions generally display lower diffusivity than benign lesions, although there are exceptions, and clinical parameters and conventional imaging modalities should also be considered in the evaluation of skull lesions. Nevertheless, in some instances diffusion-weighted imaging (DWI) can be used for problem solving when conventional imaging features are indeterminate, such as with skull base involvement by nasopharyngeal carcinoma versus osteomyelitis. In addition, DWI may be useful for monitoring treatment effects. The use of readout segmented technique, parallel imaging, multishot acquisition, turbo spin-echo DWI, diffusion tensor imaging, and higher field strengths can improve image quality. The feasibility of implementing DWI for characterizing skull lesions, the DWI findings of benign and malignant skull lesions, and technical considerations are discussed in this article.

Cavernous malformation tumors: a case study and review of the literature.

Objective: To summarize the current literature on the surgical management of cavernous malformations of the cerebellopontine angle in accordance with the experience at our institution. Methods: A systematic literature review on cavernous malformations of the cerebellopontine angle yielded 14 case reports relevant to the disease. In addition, the authors include their own report of a 16-year-old girl with such a lesion cured by surgical resection. Results: The most common clinical signs associated with this tumor are hearing loss (86.7%), followed by facial paresis (53.8%). Symptoms may be rapidly progressive. Cavernous malformations range from isointense to hyperintense to brain on noncontrasted T1 magnetic resonance imaging. In general, outcomes for patients with this tumor are favorable, with most patients cured by surgical resection. Conclusion: One of the rarest lesions of the cerebellopontine angle is a cavernous malformation. An understanding of the clinical and radiographic differences between this lesion and a vestibular schwannoma helps to minimize perioperative morbidity. Surgical resection should be performed with special attention to preserving facial nerve function.

Intracranial Salivary Gland Choristoma within Optic Nerve Dural Sheath: Case Report and Review of the Literature

OBJECTIVE Salivary gland choristomas or their neoplastic derivatives may appear throughout the intracranial space, most frequently in the middle ear or sella. Here, we present the case of a salivary gland choristoma embedded within the optic nerve dural sheath and review the literature of intracranial salivary gland masses. CASE PRESENTATION A 28-year-old female patient presented with headache and visual complaints. Magnetic resonance imaging revealed a prechiasmatic suprasellar cystic lesion. Operatively, the mass appeared as a cyst filled with mucinous fluid associated with abnormal tissue embedded within the optic nerve. RESULTS We deflated and biopsied the cyst, which revealed normal-appearing salivary tissue. The patient remains asymptomatic without radiographic evidence of cyst recurrence 2 years postoperatively. CONCLUSION Intracranial salivary tissue has been previously described but never before in the suprasellar space. Although rare, knowledge of their natural history and pathologic features may inform surgical management if they are encountered in the operating room.