Imaging of brain tumors in children: the basics-a narrative review

Imaging of pediatric glioneuronal and neuronal tumors

Glioneuronal tumors (GNTs) are an expanding group of primary CNS neoplasms, commonly affecting children, adolescents and young adults. Most GNTs are relatively indolent, low-grade, WHO grade I lesions. In the pediatric age group, GNTs have their epicenter in the cerebral cortex and present with seizures. Alterations in the mitogen-activated protein kinase (MAPK) pathway, which regulates cell growth, are implicated in tumorigenesis. Imaging not only plays a key role in the characterization and pre-surgical evaluation of GNTs but is also crucial role in follow-up, especially with the increasing use of targeted inhibitors and immunotherapies. In this chapter, we review the clinical and imaging perspectives of common pediatric GNTs.

Predictors of postoperative complications and functional outcomes in pediatric patients with surgically treated fourth ventricle tumors

BACKGROUND

Tumors of the fourth ventricle are frequently treated pathologies in pediatric neurosurgery. Data regarding predictors for permanent neurological deficits, long-term functional outcomes, cerebellar mutism (CM), the extent of resection (EOR), and oncological outcomes are scarce. We attempt to contribute to this topic with an analysis of our institutional cohort.

METHODS

A retrospective single-center study of patients aged ≤ 19 years who underwent primary surgical resection of a fourth ventricular tumor over a 15-year period (2006-2021). Predictors analyzed included age, gender, surgical approach, anatomical pattern, tumor grade, EOR, tumor volume, and others as appropriate.

RESULTS

One hundred six patients were included (64 males, mean age 7.3 years). The rate of permanent neurological deficit was 24.2%; lateral tumor extension (p = 0.036) and tumor volume greater than 38 cm3 (p = 0.020) were significant predictors. The presence of a deficit was the only significant predictor of reduced (less than 90) Lansky score (p = 0.005). CM occurred in 20.8% of patients and was influenced by medulloblastoma histology (p = 0.011), lateral tumor extension (p = 0.017), and male gender (p = 0.021). No significant difference between the transvermian and telovelar approach in the development of CM was detected (p = 0.478). No significant predictor was found for the EOR. EOR was not found to be a significant predictor of overall survival for both low-grade and high-grade tumors; however, gross total resection (GTR) was protective against tumor recurrence compared to near-total or subtotal resection (p < 0.001). In addition, survival was found to be better in older patients (≥ 7.0 years, p = 0.019).

CONCLUSION

The overall rate of postoperative complications remains high due to the eloquent localization. Older patients (> 7 years) have been found to have better outcomes and prognosis. Achieving GTR whenever feasible and safe has been shown to be critical for tumor recurrence. CM was more common in patients with medulloblastoma and in patients with tumors extending through the foramen of Luschka. The telovelar approach uses a safe and anatomically sparing corridor; however, it has not been associated with a lower incidence of CM and neurological sequelae in our series, showing that each case should be assessed on an individual basis.

Decoding Diffuse Midline Gliomas: A Comprehensive Review of Pathogenesis, Diagnosis and Treatment

Diffuse midline gliomas (DMGs) are a group of aggressive CNS tumors, primarily affecting children and young adults, which have historically been associated with dismal outcomes. As the name implies, they arise in midline structures in the CNS, primarily in the thalamus, brainstem, and spinal cord. In more recent years, significant advances have been made in our understanding of DMGs, including molecular features, with the identification of potential therapeutic targets. We aim to provide an overview of the most recent updates in the field of DMGs, including classification, molecular subtypes, diagnostic techniques, and emerging therapeutic strategies including a review of the ongoing clinical trials, thus providing the treating multidisciplinary team with a comprehensive understanding of the current landscape and potential therapeutic strategies for this devastating group of tumors.

Treatments associated with all-cause mortality among children with primary brain and central nervous system tumors: a retrospective cohort study from the SEER database

Background

Evidence on treatment modalities and survival in childhood primary brain and central nervous system (CNS) tumors remains contradictory, with previous studies often lacking sufficient patient cohort sizes to assess the differences in histological subtypes. This cohort study based on a large population investigated the effects of various treatments on the mortality of patients with different histological types of primary brain and CNS tumors from the Surveillance, Epidemiology, and End Results (SEER) database.

Methods

Data of demography, primary tumor site, histology, tumor grade and treatments from all pediatric patients with primary brain and CNS tumors were extracted in this retrospective cohort. The outcomes were overall, 1-, 5-, and 10-year all-cause mortality. Multivariate Cox proportional hazards models were to explore the associations of treatment with overall, 1-, 5-, and 10-year all-cause mortality, with hazard ratios (HRs) and 95% confidence intervals (CIs).

Results

Totally 10,994 children were included, with the mean age at diagnosis of 7.3 years, and the median follow-up time of 5.0 years. Of which, 2,003 (18.2%) were diffuse astrocytoma, 3,188 (29.0%) were embryonal tumors, and 3,691 (33.5%) were malignant glioma. Then 4,333 (39.41%) children died during the follow-up. For diffuse astrocytomas and malignant gliomas, patients who received all other treatments were associated with overall, 1-, 5- and 10-year all-cause mortality compared to those only received resection. Embryonal tumors patients receiving resection with radiation only and those receiving resection with both chemotherapy and radiation were associated with lower odds of overall, 1-, 5- and 10-year all-cause mortality compared to patients who only received resection. For ependymal tumors, no surgery/only biopsy with chemotherapy, resection with chemotherapy only, resection with both chemotherapy and radiation, and other treatments had increased risks of overall all-cause mortality compared with resection. The risk of 1-year all-cause mortality increased in ependymal tumors with treatment involving resection and radiation. However, resection with both chemotherapy and radiation was not significantly associated with the 1- nor 5-year all-cause mortality.

Conclusions

Resection may be recommended for children with diffuse astrocytoma, ependymal tumors, and malignant glioma, while resection with radiotherapy or chemoradiation may be recommended for children with embryonal tumors.

Imaging Guidelines and Recommendations for Diagnosis, Surveillance, and Management of Pediatric CNS and Spinal Tumors

Central nervous system (CNS) tumors are the second most common cause of cancer in children when incidence rates of cancer are estimated according to the Indian population dynamics based on 2011 consensus. As per the estimates, CNS tumors account for 20.1% of cancer burden in children aged between 0 and 14 years and 16.8% when 0 to 19 years age group is considered. The most common pediatric brain tumors are astrocytoma and medulloblastoma followed by other embryonal tumors, craniopharyngioma, and ependymal tumors. The incidence of CNS tumors in children from India is similar to the western high-income countries, other than slightly higher incidence of craniopharyngioma in Indian children.

Intraoperative MRI versus intraoperative ultrasound in pediatric brain tumor surgery: is expensive better than cheap? A review of the literature

PURPOSE

The extent of brain tumor resection (EOR) is a fundamental prognostic factor in pediatric neuro-oncology in association with the histology. In general, resection aims at gross total resection (GTR). Intraoperative imaging like intraoperative US (iOUS) and MRI have been developed in order to find any tumoral remnant but with different costs. Aim of our work is to review the current literature in order to better understand the differences between costs and efficacy of MRI and iOUS to evaluate tumor remnants intraoperatively.

METHODS

We reviewed the existing literature on PubMed until 31st December 2021 including the sequential keywords "intraoperative ultrasound and pediatric brain tumors", "iUS and pediatric brain tumors", "intraoperative magnetic resonance AND pediatric brain tumors", and "intraoperative MRI AND pediatric brain tumors.

RESULTS

A total of 300 papers were screened through analysis of title and abstract; 254 were excluded. After selection, a total of 23 articles were used for this systematic review. Among the 929 patients described, a total of 349(38%) of the cases required an additional resection after an iMRI scan. GTR was measured on 794 patients (data of 69 patients lost), and it was achieved in 552(70%) patients. In case of iOUS, GTR was estimated in 291 out of 379 (77%) cases. This finding was confirmed at the post-operative MRI in 256(68%) cases.

CONCLUSIONS

The analysis of the available literature demonstrates that expensive equipment does not always mean better. In fact, for the majority of pediatric brain tumors, iOUS is comparable to iMRI in estimating the EOR.