Can Preoperative Mapping with Functional MRI Reduce Morbidity in Brain Tumor Resection? A Systematic Review and Meta-Analysis of 68 Observational Studies

Abstract

F unctional MRI (fMRI) is increasingly implemented as a practical preoperative planning tool for brain tumor resection, but a considerable discrepancy between its current use and presumed utility remains. A recent survey among neurosurgeons found variability in the present use and assumed utility of fMRI for preoperative surgical planning in patients with brain tumors. This variation includes clinical and radiographic indications for ordering fMRI, functional paradigms to test in specific case studies, and clinical purposes of using fMRI (1).Surgical resection of brain tumors aims to maximize tumor removal while avoiding the onset of permanent postoperative deficits. The extent of tumor resection independently correlates with patient survival (2,3). However, when resective surgery extends too far into infiltrated critical structures, the condition of the patient permanently worsens; this, in turn, compromises both quality of life and survival. Several neurosurgical advances aim to improve patient outcomes. To localize critical brain structures and the tumor, techniques such as preoperative functional neuroimaging, neuronavigation, fluorescent dyes, MRI in the surgical field, and intraoperative stimulation mapping have been used (4). Although meta-analyses have assessed the use of intraoperative stimulation mapping, awake craniotomy, and intraoperative MRI (4-6), the usefulness of these techniques and their effect on neurologic outcomes have not been sufficiently addressed in randomized trials or meta-analyses. These studies suggest that glioma resections that use intraoperative stimulation mapping and awake craniotomy are associated with better surgical outcomes, fewer late severe neurologic deficits, and a higher percentage of gross total resections (4,6). However, a recent meta-analysis of five studies comparing the use of the intraoperative fMRI with standard neuronavigation (5) showed attenuated incidence of postsurgical permanent neurologic deficits, although this finding was not statistically significant.The primary objective of our study was to assess the overall postoperative morbidity within at least a 2-month Background: Preoperative functional MRI (fMRI) is one of several techniques developed to localize critical brain structures and brain tumors. However, the usefulness of fMRI for preoperative surgical planning and its potential effect on neurologic outcomes remain unclear.Purpose: To assess the overall postoperative morbidity among patients with brain tumors by using preoperative fMRI versus surgery without this tool or with use of standard (nonfunctional) neuronavigation. Materials and Methods:A systematic review and meta-analysis of studies across major databases from 1946 to June 20, 2020, were conducted. Inclusion criteria were original studies that (a) included patients with brain tumors, (b) performed preoperative neuroimaging workup with fMRI, (c) investigated the usefulness of a preoperative or intraoperative functional neuroimaging technique and used that technique to resect cerebral tumors...

Data-efficient resting-state functional magnetic resonance imaging brain mapping with deep learning

“…There is strong evidence in the literature that accurate preoperative fMRI planning prior to the resection of brain tumors reduces postsurgical morbidity. 38 With current task-based methods, however, the time it takes to get adequate information can extend the scan time up to an hour. Thus, there is a high degree of significance for the neurosurgeon in obtaining optimal imaging quality while reducing imaging time and cost.…”

“…A recent meta-analysis has demonstrated that presurgical planning with T-fMRI improves morbidity and mortality. 38 Multiple studies have demonstrated that RS-fMRI mapping can complement T-fMRI and provide necessary mapping when a patient is unable to cooperate with the study or the task fails for some other reason. 10 The low failure rate of RS-fMRI, the automated localization capability of the 3DCNN, and the need for far less scanner time make the proposed method an attractive choice for the preoperative assessment of tumor patients.…”

Validation of Non-invasive Language Mapping Modalities for Eloquent Tumor Resection: A Pilot Study

“… Roux et al (2003) showed that all of the 22 intraoperatively identified positive language sites were correlated to preoperative fMRI. A recent meta-analysis showed that preoperative fMRI decreases postoperative neurological morbidity ( Luna et al, 2021 ), whereas a recent review found that fMRI has shown excellent utility for lateralizing language dominance, superior to the Wada test for many patients ( Qadri et al, 2021 ). It is possible that combining task-based fMRI with cerebrovascular reactivity mapping (CVR) may help overcome some of the issues related to vascular uncoupling in the presence of brain tumors, although the impact of CVR mapping upon the accuracy of fMRI compared with DCS has not been adequately investigated to date.…”

“…However, the statistical validity of these results remains in question because of the significant differences in data collection and aggregation between TMS and fMRI, leading to far more data points for TMS despite a similar number of patients. In addition, TMS lacks large, aggregated studies showing its clinical utility for preoperative language mapping ( Luna et al, 2021 ). TMS also lacks comparable evidence to fMRI with respect to lateralizing language dominance ( Qadri et al, 2021 ).…”

What Can Resting-State fMRI Data Analysis Explain about the Functional Brain Connectivity in Glioma Patients?

“…Tb-fMRI is already widely applied for this purpose, as it was found to be reliable in identifying the motor and language networks [3,4]. Moreover, meta-analytic studies and comparisons with direct electrical stimulation (DES), the gold standard in terms of localization of functional areas at the intraoperative level, support that tb-fMRI is a robust tool for presurgical motor planning [5] and may mitigate morbidity and neurological deficits in the postoperative phase [6]. Nevertheless, this technique presents some limitations, mainly associated with the acquisition: it is necessary for the patients to be able and suitable to be trained to perform the task; therefore, they should not present severe neurological deficits or cognitive impairment.…”