Imaging Evaluation of Plexiform Neurofibromas in Neurofibromatosis Type 1: A Survey-Based Assessment.

OBJECTIVE: To assess imaging utilization practices across clinical specialists in neurofibromatosis type 1 (NF1) for the evaluation of symptomatic and asymptomatic children and adults with or without plexiform neurofibromas (PN). METHODS: An institutional review board-exempt survey was administered to medical practitioners caring for individuals with NF1 at the Response Evaluation in Neurofibromatosis and Schwannomatosis (REiNS) meeting in September 2019. The survey included questions on respondent demographic data (9 questions), type of imaging obtained for asymptomatic (4 questions) and symptomatic (4 questions) people with and without PN, and utilization of diffusion-weighted imaging (2 questions). RESULTS: Thirty practitioners participated in the survey. Most were academic neuro-oncologists at high-volume (>10 patients/week) NF1 centers. Of 30 respondents, 26 had access to whole-body MRI (WB-MRI). The most common approach to an asymptomatic person without PN was no imaging (adults: 57% [17/30]; children: 50% [15/30]), followed by a screening WB-MRI (adults: 20% [6/30]; children: 26.7% [8/30]). The most common approach to a person with symptoms or known PN was regional MRI (adults: 90% [27/30]; children: 93% [28/30]), followed by WB-MRI (adults: 20% [6/30]; children: 36.7% [11/30]). WB-MRI was most often obtained to evaluate a symptomatic child with PN (37% [11/30]). CONCLUSIONS: More than 90% of practitioners indicated they would obtain a regional MRI in a symptomatic patient without known or visible PN. Otherwise, there was little consensus on imaging practices. Given the high prevalence of PN and risk of malignant conversion in this patient population, there is a need to define imaging-based guidelines for optimal clinical care and the design of future clinical trials.

Quantitative assessment and clinical relevance of VEGFRs-positive tumor cells in refractory brain tumors.

Vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR)1 and 2 signaling is a potent activator of tumor angiogenesis. Although the expressions of VEGFR1 and VEGFR2 were initially thought to be limited to the endothelial cells, it is now known that both the receptors are expressed in tumor cells. This is the first study wherein VEGFRs-positive tumor cells are quantitatively evaluated for brain tumors with upregulated VEGF/VEGFR signaling. The percentage of VEGFRs-positive tumor cells was quantitatively evaluated in various brain tumors (10 glioblastomas, 22 neurofibromatosis type 2 [NF2]-related schwannomas, 21 sporadic schwannomas, 27 chordomas, 36 meningiomas, 29 hemangioblastomas, 11 hemangiopericytoma, and 13 ependymomas) using immunohistochemistry. VEGF-A expression was also analyzed using quantitative real-time polymerase chain reaction. Double immunofluorescence staining using anti-PDGFR-ß and anti-CD34 antibody, microvessel density, and vessel diameter were analyzed to evaluate the vascular characteristics. Chordomas demonstrated an extremely higher percentage of VEGFR1 and VEGFR2-positive tumor cells than other tumors. In contrast, meningiomas and hemangiopericytomas showed few VEGFRs-positive tumor cells. The percentage of positive tumor cells in chordomas, hemangioblastomas, and NF2 schwannomas was associated with clinical courses, such as shorter progression free survival, and growth speed. Glioblastomas and NF2 schwannomas showed larger tumor vessels without pericyte coverage. The present study is the first to quantitatively analyze VEGFR1- and VEGFR2- positive tumor cells in various types of refractory brain tumors. This novel parameter significantly correlated with the progressive clinical courses.

Endoglin-based assessment of neoangiogenesis in sporadic VIII cranial nerve schwannoma.

Although the diagnosis and treatment of sporadic vestibular schwannoma has improved in recent years, no factors capable of predicting its growth have been identified as yet. Endoglin (CD105) is a proliferation-associated protein expressed in angiogenic endothelial cells, and a potential prognostic indicator for several solid tumors. The aim of the present study was primarily to investigate the expression and role of CD105 in a series of sporadic vestibular nerve schwannomas. In 71 consecutive cases of vestibular schwannoma, vessel cross-sectional area and density were calculated from immunohistochemically assessed CD105 expression using image analysis to correlate them with: (i) tumor dimensions; and (ii) tumor growth rate measured on high-resolution contrast-enhanced MRI (ceMRI). Based on assessments of CD105 expression, a significant positive correlation was identified between vessel cross-sectional area and tumor size at the time of surgery (p = 0.0024), and between vessel density and tumor size (p = 0.013). Vessel cross-sectional area (p = 0.0006) and vessel density (p = 0.003) were significantly greater in tumors measuring ≥10 mm in size than in those <10 mm. Conversely, when tumor growth rate could be calculated from two or more ceMRI (38 cases), there was no significant correlation between tumor growth rate and cross-sectional vessel area or vessel density as assessed with CD105. Further investigations are needed to ascertain the feasibility of: (i) using circulating endoglin assay to monitor tumor growth; and (ii) targeting neoangiogenesis with anti-endoglin antibodies in sporadic vestibular schwannoma.

Correlation between radiological assessment and histopathological diagnosis in retroperitoneal tumors: analysis of 291 consecutive patients at a tertiary reference sarcoma center.

OBJECTIVES: Aim of study was to assess the correlation between computed tomography scan (CT) findings and histopathology. MATERIAL AND METHODS: Data were collected on consecutive patients with suspected retroperitoneal sarcoma (RPS) referred to a tertiary sarcoma center. Patients underwent contrast enhanced multi-detector CT scans. Radiological features of lesions were classified according to the presence of a fatty (Group A) mass, or non-fatty (Group B) mass, both subdivided according to homogeneity and intralesional high-contrasted appearance. Radiological classification was compared with histopathological diagnosis. Sensitivity, specificity, positive/negative predictive value (PPV, NPV) were analyzed. RESULTS: Of 291 patients, 103/291 (35.4%) masses were classified in Group A and 188/291 (64.6%) in Group B. Diagnosis of mesenchymal tumor was obtained in 231/291 cases (79%) and non-mesenchymal tumor in 60/291 (21%). Sensitivity and specificity of Group A for liposarcoma were 76.7% and 92.0%; PPV and NPV were 86.4% and 85.6%. Sensitivity of Group B for a mesenchymal tumor was 55.4% and specificity was 0%; PPV and NPV were 68.1% and 0%. CONCLUSIONS: None of radiological criteria were sufficient to anticipate a specific diagnosis, with the only exception of well differentiated liposarcoma and angiomyolipoma. In a series of suspected RPS, 21% of the lesions were finally non-mesenchymal tumors.

Assessment of tumor blood flow and its correlation with histopathologic features in skull base meningiomas and schwannomas by using pseudo-continuous arterial spin labeling images.

OBJECTIVE: We aimed to investigate whether pseudo-continuous arterial spin labeling (pcASL)-MRI can adequately evaluate tumor perfusion even if the tumors are located in the skull base region and evaluate the correlation between tumor blood flow (TBF) and the histopathologic features of skull base meningiomas and schwannomas. MATERIALS AND METHODS: We enrolled 31 patients with skull base meningioma (n=14) and schwannoma (n=17) who underwent surgical resection. TBF was calculated from pcASL. Tissue sections were stained with CD34 to evaluate microvessel area (MVA). TBF and MVA ratio were compared between meningiomas and schwannomas using Mann-Whitney U-test. The correlations between MVA ratio and TBF were evaluated in each tumor by using single linear regression analysis and Spearman's rank correlation coefficients (rs). RESULTS: MVA ratio and TBF were significantly higher in meningioma than in schwannoma (both p<0.01). Correlation analyses revealed significant positive correlations between MVA ratio and both mean and max TBF for meningiomas (rs=0.89, 0.81, both p<0.01). There was a weak positive correlation between MVA ratio and mean TBF for schwannomas (rs=0.43, p=0.04). However, no significant correlation was found between MVA ratio and max TBF for schwannoma. CONCLUSIONS: pcASL-MRI is useful for evaluating tumor perfusion even if the tumors are located in the skull base region. Moreover, pcASL-TBF was significantly higher in most meningiomas compared to schwannomas, which can help in the differential diagnosis of the 2 tumor types even without the use of contrast material.

Head and neck tumors: assessment of perfusion-related parameters and diffusion coefficients based on the intravoxel incoherent motion model.

BACKGROUND AND PURPOSE: IVIM MR imaging provides perfusion and diffusion information with a single diffusion-weighted MR image. We determined whether PP and D differ among various types of head and neck tumors. MATERIALS AND METHODS: The study cohort included 123 head and neck tumors: 30 SCCs, 28 benign and 20 malignant SG tumors, 36 lymphomas, and 9 schwannomas. The D and PP values were determined by using b-values of 0, 500, and 1000 s/mm(2) based on the IVIM model. RESULTS: The PP values (lymphomas, 0.09 ± 0.04; SCCs, 0.15 ± 0.04; and malignant SG tumors, 0.22 ± 0.07) and D values (0.47 ± 0.07 × 10(-3) mm(2)/s, 0.82 ± 0.17 × 10(-3) mm(2)/s, and 1.03 ± 0.16 × 10(-3) mm(2)/s, respectively) were significantly different among the malignant tumors (P < .01). These values were also significantly different between pleomorphic adenomas (0.13 ± 0.02 and 1.44 ± 0.39 × 10(-3) mm(2)/s) and Warthin tumors (0.19 ± 0.04 and 0.73 ± 0.22 × 10(-3) mm(2)/s) (P < .001). The PP values of malignant SG tumors were significantly different from those of pleomorphic adenomas (P = .001) and the D values of the malignant SG tumors were significantly different from those of pleomorphic adenomas (P = .002) and Warthin tumors (P = .007). Schwannomas had large PP (0.23 ± 0.08) and D values (1.26 ± 0.20 × 10(-3) mm(2)/s), greatly overlapping those of some SG tumor types. CONCLUSIONS: Head and neck tumors had distinctive PP and D values by using IVIM MR imaging.

Quantitative assessment of whole-body tumor burden in adult patients with neurofibromatosis.

PURPOSE: Patients with neurofibromatosis 1 (NF1), NF2, and schwannomatosis are at risk for multiple nerve sheath tumors and premature mortality. Traditional magnetic resonance imaging (MRI) has limited ability to assess disease burden accurately. The aim of this study was to establish an international cohort of patients with quantified whole-body internal tumor burden and to correlate tumor burden with clinical features of disease. METHODS: We determined the number, volume, and distribution of internal nerve sheath tumors in patients using whole-body MRI (WBMRI) and three-dimensional computerized volumetry. We quantified the distribution of tumor volume across body regions and used unsupervised cluster analysis to group patients based on tumor distribution. We correlated the presence and volume of internal tumors with disease-related and demographic factors. RESULTS: WBMRI identified 1286 tumors in 145/247 patients (59%). Schwannomatosis patients had the highest prevalence of tumors (P = 0.03), but NF1 patients had the highest median tumor volume (P = 0.02). Tumor volume was unevenly distributed across body regions with overrepresentation of the head/neck and pelvis. Risk factors for internal nerve sheath tumors included decreasing numbers of café-au-lait macules in NF1 patients (P = 0.003) and history of skeletal abnormalities in NF2 patients (P = 0.09). Risk factors for higher tumor volume included female gender (P = 0.05) and increasing subcutaneous neurofibromas (P = 0.03) in NF1 patients, absence of cutaneous schwannomas in NF2 patients (P = 0.06), and increasing age in schwannomatosis patients (p = 0.10). CONCLUSION: WBMRI provides a comprehensive phenotype of neurofibromatosis patients, identifies distinct anatomic subgroups, and provides the basis for investigating molecular biomarkers that correlate with unique disease manifestations.

Evolution in the assessment and management of trigeminal schwannoma.

EDUCATIONAL OBJECTIVE: At the conclusion of this presentation, the participants should be able to understand the contemporary assessment and management algorithm used in the evaluation and care of patients with trigeminal schwannomas. OBJECTIVES: 1) Describe the contemporary neuroradiographic studies for the assessment of trigeminal schwannoma; 2) review the complex skull base osteology involved with these lesions; and 3) describe a contemporary management algorithm. STUDY DESIGN: Retrospective review of 23 cases. METHODS: Chart review. RESULTS: From 1984 to 2006, of 23 patients with trigeminal schwannoma (10 males and 13 females, ages 14-77 years), 15 patients underwent combined transpetrosal extirpation, 5 patients underwent stereotactic radiation, and 3 were followed without intervention. Of the 15 who underwent surgery, total tumor removal was achieved in 9 patients. Cytoreductive surgery was performed in six patients; of these, four received postoperative radiation. One patient who underwent primary radiation therapy required subsequent surgery. There were no deaths in this series. Cranial neuropathies were present in 14 patients pretreatment and observed in 17 patients posttreatment. Major complications included meningitis (1), cerebrospinal fluid leakage (2), major venous occlusion (1), and temporal lobe infarction (1). CONCLUSIONS: Trigeminal schwannomas are uncommon lesions of the skull base that may occur in the middle fossa, posterior fossa, or both. Moreover, caudal extension results in their presentation in the infratemporal fossa. Contemporary diagnostic imaging, coupled with selective use of both surgery and radiation will limit morbidity and allow for the safe and prudent management of this uncommon lesion.

Cranial nerve assessment in posterior fossa tumors with fast imaging employing steady-state acquisition (FIESTA).

Steady-state free precession is widely used for ultra-fast cardiac or abdominal imaging. The purpose of this work was to assess fast imaging employing steady-state acquisition (FIESTA) and to evaluate its efficacy for depiction of the cranial nerve affected by the tumor. Twenty-three consecutive patients with posterior fossa tumors underwent FIESTA sequence after contrast agent administration, and then displacement of the cranial nerve was evaluated. The 23 patients with posterior fossa tumor consisted of 12 schwannomas, eight meningiomas, and three cases of epidermoid. Except in the cases of epidermoid, intensity of all tumors increased on FIESTA imaging of the contrast enhancement. In the schwannoma cases, visualization of the nerve became poorer as the tumor increased in size. In cases of encapsulated meningioma, all the cranial nerves of the posterior fossa were depicted regardless of location. The ability to depict the nerves was also significantly higher in meningioma patients than in schwannoma patients (P<0.05). In cases of epidermoid, extension of the tumors was depicted clearly. Although the FIESTA sequence offers similar contrast to other heavily T2-weighted sequences, it facilitated a superior assessment of the effect of tumors on cranial nerve anatomy. FIESTA sequence was useful for preoperative simulations of posterior fossa tumors.

[Tumors of the temporal bone and the cerebellopontine angle. Diagnosis, characterization and assessment of extension by using imaging technics]. / Tumori dell'osso temporale e dell'angolo ponto-cerebellare. Diagnosi, caaratterizzazione e bilancio di estensione con le tecniche ad immagini.

We discuss in this paper the reliability of neuroimaging techniques in the diagnosis of neoplastic masses of the posterior-lateral skull base. We also discuss the role of TC and MRI in the evaluation of the extension pattern of these masses.

Magnetic resonance imaging of peripheral nerve sheath tumors. Assessment by numerical visual fuzzy cluster analysis.

A retrospective, nonblinded review of ten nerve sheath tumors (four malignant) selected for pathologic proof and complete magnetic resonance (MR) evaluation was performed to assess the primary tumor location, signal pattern, and extent of reactive zone. A modification of visual fuzzy cluster analysis (VFCA) that emphasized the number of visual fuzzy clusters in each mass was developed to assess the neural tumors. The MR findings were correlated with the findings at surgery and histopathology. There were six men and four women, aged 19 to 62 years (mean, 43). Nine tumors involved the lower extremity. In all tumors, MRI correctly identified the nerve trunk of origin. Tumor dimensions were generally overestimated by MRI. Three internal signal patterns were observed: homogeneous (1/1 benign), finitely inhomogeneous (5/5 benign), and hectically inhomogeneous (4/4 malignant). The number of visual fuzzy clusters (VFCRs) for each sequence did not allow reliable separation of benign and malignant entities, but when considered in aggregate, benign and malignant lesions segregated in different clusters. This implies that the likelihood of malignancy increases as the number of MR-identifiable tissue types per lesion increase. Three types of reaction (edema) were observed best on long repetition time/echo time (TR/TE) sequences, confined to immediate peritumoral region, intracompartmental, and extracompartmental. The first two patterns correlated well with clinicopathologic findings; however, the third pattern did not. Separation of indolent (benign) cellular masses from aggressive (malignant) ones by MR characteristics is difficult but VFCA shows promise for aiding this differentiation and deserves further investigation in larger study populations.

Assessment and treatment of neurogenic and non-neurogenic tumors of the parapharyngeal space.

The clinical and pathologic findings in eleven cases of parapharyngeal space tumors are described. The anatomy of this area and diagnostic procedures are discussed. Investigations should include a few basic examinations such as sialogram-computed tomographic (CT) scan, carotid angiogram, and echography. Several surgical approaches are considered in relation to the site and the size of the neoplasm. Prognosis depends on the histologic type of the tumor.