Preoperative functional magnetic resonance imaging in patients undergoing surgery for tumors around left (dominant) inferior frontal gyrus region

Systematic review of functional magnetic resonance imaging (fMRI) applications in the preoperative planning and treatment assessment of brain tumors

The utilization of functional magnetic resonance imaging (fMRI) is critical in the preoperative planning phase of brain tumor surgery because it allows for a delicate balance between maximizing tumor resection and maintaining brain function. A decade of fMRI development was examined in this study, with a particular emphasis on its use in diagnosing and assessing the efficacy of brain cancer treatments. We examined the foundational principles, practical implementations, and verification of fMRI via direct brain stimulation, with particular emphasis on its capacity to detect cerebral regions affected by tumors that are eloquent in nature. Recently, fMRI has undergone significant progress, allowing for its integration into clinical workflows to facilitate precise mapping of brain functions. This extensive analysis encompasses the scrutiny of resting-state fMRI (Rs-fMRI) as a method of capturing functional connectivity, thereby providing significant insights into the management of patients with brain tumors. Methodological advancements, clinical applicability, and future orientations of fMRI are highlighted in this review, which emphasizes the substantial influence of the technique on neurosurgical planning and patient outcomes.

Exploring cognitive Landscapes: Longitudinal Dynamics of left insula gliomas using neuropsychological inquiry, fMRI, and intra-resection real time neuropsychological testing

We explored the functional outcome following awake surgery and Real-Time Neuropsychological Testing (RTNT) in the left insula. We carried out a longitudinal investigation by comparing the patients' language profile, and, in particular, the object-naming skills and the associated fMRI network, of pre-surgery and follow-up (i.e., a few months after surgery) in a group of 23 patients harboring a left-sided low grade glioma centered to the insulo-temporal area. Tumor resection, performed while continuously monitoring patients' performance by RNTN, was high (median = 92 %). From the neuropsychological viewpoint, almost all patients displayed preserved naming and language skills in general, both before surgery and at follow-up, when they recovered from a transient impairment recorded immediately after surgery. From the functional imaging viewpoint, the naming networks of the two assessment times were almost equivalent, with non-parametric analyses showing brain remodeling involving perilesional areas preoperatively and the contralesional, healthy, insula at follow-up. We discussed the anatomo-functional mechanisms that contributed to the preservation of the functional and cognitive pattern as observed in this longitudinal study, with a particular focus on the promising plasticity potential of the left insular area. In particular, we commented that, at least in our patient series and by applying an optimized surgical procedure, surgery in the insula was safe and generally contributed to the preservation of the language functions.

Does Functional Imaging Play a Role in Pre-Operative Diagnosis of Brain Tumours?

Although there is a large variability in the neural organization of language function between individuals, there is an ongoing debate about functional imaging as a standard procedure in the preoperative setting of brain tumors. Brain mapping of the language centers differs from individual to individual in multilingual patients and changes in its architecture may occur as a result of neuroplasticity induced by a mass lesion. This article discusses the role of functional imaging in the preoperative setting.

Reorganization and Plasticity of the Language Network in Patients with Cerebral Gliomas

Language is organized in large-scale networks in the human brain that show a strong potential for flexible interactions and adaptation. Neuroplasticity is the central mechanism that allows such dynamic modulation to changing conditions across the life span and is particularly important for network reorganization after brain lesions. Most studies on language reorganization focused on language recovery after stroke. Yet, a strong degree of adaptive neuroplasticity can also be observed in patients with brain tumors in language-eloquent brain areas. This review discusses key mechanisms for neural reorganization in patients with brain tumors. Our main aim is to elucidate the underlying mechanisms for intra- and interhemispheric plasticity in the language network in these patients. The following reorganization patterns are discussed: 1) Persisting function within the tumor; 2) Reorganization in perilesional regions; 3) Reorganization in a distributed network of the affected hemisphere; 4) Reorganization to the contralesional hemisphere. In this context, we shed light on language-related reorganization patterns in frontal and temporo-parietal areas and discuss their functional relevance. We also address tumor-related changes in structural and functional connectivity between eloquent brain regions. Thereby, we aim to expand the general understanding of the plastic potential of the neural language network and facilitate clinical decision-making processes for effective, function-preserving tumor treatment.

Contralesional Cortical and Network Features Associated with Preoperative Language Deficit in Glioma Patients

Simple Summary

Gliomas that infiltrate eloquent areas can damage the corresponding cortical or subcortical structures, leading to language dysfunction. A total of 20–40% of eloquent area glioma patients have language deficits. Gliomas anchored in eloquent areas cause varying degrees of language impairment. A tumor’s size, grade, location, and contralesional compensation may explain these differences. This study aimed to retrospectively explore gray and white matter plasticity in the contralesional hemisphere of patients with gliomas in the eloquent area using VBM and DTI network analysis.

Abstract

Lower-grade Gliomas anchored in eloquent areas cause varying degrees of language impairment. Except for a tumor’s features, contralesional compensation may explain these differences. Therefore, studying changes in the contralateral hemisphere can provide insights into the underlying mechanisms of language function compensation in patients with gliomas. This study included 60 patients with eloquent-area or near-eloquent-area gliomas. The participants were grouped according to the degree of language defect. T1 and diffusion tensor imaging were obtained. The contralesional cortical volume and the subcortical network were compared between groups. Patients with unimpaired language function showed elevated cortical volume in the midline areas of the frontal and temporal lobes. In subcortical networks, the group also had the highest global efficiency and shortest global path length. Ten nodes had intergroup differences in nodal efficiency, among which four nodes were in the motor area and four nodes were in the language area. Linear correlation was observed between the efficiency of the two nodes and the patient’s language function score. Functional compensation in the contralesional hemisphere may alleviate language deficits in patients with gliomas. Structural compensation mainly occurs in the contralesional midline area in the frontal and temporal lobes, and manifests as an increase in cortical volume and subcortical network efficiency.

Epilepsy enhance global efficiency of language networks in right temporal lobe gliomas

AIMS

We analyzed the resting state functional magnetic resonance images to investigate the alterations of neural networks in patients with glioma-related epilepsy (GRE).

METHODS

Fifty-six patients with right temporal lower-grade glioma were divided into GRE (n = 28) and non-GRE groups. Twenty-eight healthy subjects were recruited after matching age, sex, and education level. Sensorimotor, visual, language, and left executive control networks were applied to generate functional connectivity matrices, and their topological properties were investigated.

RESULTS

No significant alterations in functional connectivity were found. The least significant discovery test revealed differences only in the language network. The shortest path length, clustering coefficient, local efficiency, and vulnerability were greater in the non-GRE group than in the other groups. The nodal efficiencies of two nodes (mirror areas to Broca and Wernicke) were weaker in the non-GRE group than in the other groups. The node of degree centrality (Broca), nodal local efficiency (Wernicke), and nodal clustering coefficient (temporal polar) were greater in the non-GRE group than in the healthy group.

CONCLUSION

Different tumor locations alter different neural networks. Temporal lobe gliomas in the right hemisphere altered the language network. Glioma itself and GRE altered the network in opposing ways in patients with right temporal glioma.

Contralesional functional network reorganization of the insular cortex in diffuse low-grade glioma patients

Diffuse low-grade gliomas (DLGGs) growing on the insular lobe induce contralesional hemispheric insular lobe compensation of damaged functioning by increasing cortical volumes. However, it remains unclear how functional networks are altered in patients with insular lobe DLGGs during functional compensation. Thirty-five patients with insular DLGGs were classified into the left (insL, n = 16) and right groups (insR, n = 19), and 33 healthy subjects were included in the control group. Resting state functional magnetic resonance imaging was used to generate functional connectivity (FC), and network topological properties were evaluated using graph theoretical analysis based on FC matrices. Network-based statistics were applied to compare differences in the FC matrices. A false discovery rate was applied to correct the topological properties. There was no difference in the FC of edges between the control and insL groups; however, the nodal shortest path length of the right insular lobe was significantly increased in the insL group compared to the control group. Additionally, FC was increased in the functional edges originating from the left insular lobe in the insR group compared to the control group. Moreover, there were no differences in topological properties between the insR and control groups. The contralesional insular lobe is crucial for network alterations. The detailed patterns of network alterations were different depending on the affected hemisphere. The observed network alterations might be associated with functional network reorganization and functional compensation.

Relationships of Language Lateralization with Diffusion Tensor Imaging Metrics of Corpus Callosum, Tumor Grade, and Tumors Distance to Language-Eloquent Areas in Glial Neoplasms

PURPOSE

The aim of the study was to search relationships between language lateralization and corpus callosum (CC) connectivity, tumor grade, and tumors distance to language-eloquent areas in glial neoplasms.

MATERIALS AND METHODS

The functional magnetic resonance imaging and CC diffusion tensor imaging (DTI) metrics of 42 patients with glial neoplasm were evaluated for relationships of language lateralization (left, right, and bilateral) with CC DTI metrics (tracts number, voxel, volume, length, fractional anisotropy [FA], and apparent diffusion coefficient), tumor grade, and tumors distance to language-eloquent areas and relationships of CC DTI metrics with tumor grade. Kruskal-Wallis, Mann-Whitney U, and χ tests were used. All were repeated in 26 patients with left hemispheric masses.

RESULTS

In glial masses, language bilateralism was more common than normal population and more pronounced in low grade than high grade. In right lateralism and bilateralism, tumor settlement nearby language-eloquent areas was more common. In the left lateralism, highest CC tract number, higher tumor grade, and more remote tumor settlements were noted. There was no relationship between CC DTI metrics and tumor grade but increase in CC tracts number and FA with increasing tumor grade.

CONCLUSIONS

Increased bilateralism in glial masses than normal population and in low grade tumors than high grade and increased nearby tumor settlement in right lateralism and bilateralism support interhemispheric reorganization and plasticity. This is more pronounced in low grade because of higher life span. Highest CC tract number, higher tumor grade, and more remote tumor settlement in left lateralized group suggest intact CC integrity with limited hemispheric destruction. Increasing CC tracts number and FA with increasing tumor grade support preserved CC integrity in the shorter life span of high-grade tumors.