Differentiating Glioma from Brain Metastasis Using Neurite Orientation Dispersion and Density Imaging: A Systematic Review and Meta-Analysis.

BACKGROUND: Differentiation between gliomas and brain metastases (BMs) remains a diagnostic challenge. Noninvasive imaging biomarkers could be advantageous in brain tumor discrimination.

PURPOSE: We aimed to systematically review the studies that measured neurite orientation dispersion and density imaging (NODDI) parameters in patients with gliomas and BMs.

DATA SOURCES: A literature search was conducted in 4 databases, including PubMed, Web of Science, EMBASE, and Scopus.

STUDY SELECTION: Studies that measured NODDI parameters, such as intracellular volume fraction (V-IC), isotropic volume fraction (V-ISO), and orientation dispersion index (ODI) in both patients with glioma and patients with BM were included.

DATA ANALYSIS: Quality was assessed using the modified Newcastle-Ottawa Scale checklist. Pooled standardized mean differences (SMDs) with corresponding 95% CIs were calculated using a random-effects model. Heterogeneity was evaluated using the I 2 statistic. Subgroup analysis was performed to explore sources of heterogeneity. Funnel plots, along with Begg and Egger tests were applied to investigate publication bias.

DATA SYNTHESIS: Ten studies were ultimately included in the systematic review. We found significant SMDs for ODI (SMD = -1.43 [-2.02, -0.85]) and V-ISO (SMD = -0.98 [-1.60, -0.37]) between gliomas and BMs in the contrast-enhancing region. Also, for the glioblastoma subgroup, V-ISO of the peritumoral edema area showed a significant SMD (SMD = -0.73 [-0.96, -0.50]). No significant differences were found for other parameters. The heterogeneity turned from high to low in specific subgroups, including the glioblastoma subgroup.

LIMITATIONS: Our meta-analysis is limited by small number of studies.

CONCLUSIONS: NODDI parameters, particularly ODI and V-ISO, can be considered useful tools for differentiating gliomas from BMs. These findings highlight the potential of NODDI as a noninvasive imaging biomarker to improve the differential diagnosis of intracranial tumors.