G liomas are the most common primary brain tumors, accounting for 80% of malignant central nervous system tumors, and can be categorized into 4 grades according to their biological behavior. Patients with low-grade gliomas (LGGs) typically survive more than 5 years. 21 Those with high-grade gliomas (HGGs) have a survival time of approximately 1-3 years. An epidemiology study using primary brain tumor data collected from 1985 to 2005 showed that the 1-year survival rate of patients with malignant glioma is 53.9%, while that of paabbreviatioNs Cho = choline; CNI = choline-NAA index; CSI = chemical shift imaging; DICOM = digital imaging and communications in medicine; DTI = diffusion tensor imaging; EOR = extent of resection; fMRI = functional MR imaging; GTR = gross-total resection; 1 H-MRS = proton MR spectroscopy; HGG = high-grade glioma; LGG = low-grade glioma; MPRAGE = magnetization-prepared rapid gradient-echo; NAA = N-acetylaspartate; OS = overall survival; PFS = progression-free survival; PT = pyramidal tract; ROI = region of interest; STR = subtotal resection; VOI = volume of interest. obJective The extent of resection is one of the most essential factors that influence the outcomes of glioma resection. However, conventional structural imaging has failed to accurately delineate glioma margins because of tumor cell infiltration. Three-dimensional proton MR spectroscopy ( 1 H-MRS) can provide metabolic information and has been used in preoperative tumor differentiation, grading, and radiotherapy planning. Resection based on glioma metabolism information may provide for a more extensive resection and yield better outcomes for glioma patients. In this study, the authors attempt to integrate 3D 1 H-MRS into neuronavigation and assess the feasibility and validity of metabolically based glioma resection. methods Choline (Cho)-N-acetylaspartate (NAA) index (CNI) maps were calculated and integrated into neuronavigation. The CNI thresholds were quantitatively analyzed and compared with structural MRI studies. Glioma resections were performed under 3D 1 H-MRS guidance. Volumetric analyses were performed for metabolic and structural images from a low-grade glioma (LGG) group and high-grade glioma (HGG) group. Magnetic resonance imaging and neurological assessments were performed immediately after surgery and 1 year after tumor resection. results Fifteen eligible patients with primary cerebral gliomas were included in this study. Three-dimensional 1 H-MRS maps were successfully coregistered with structural images and integrated into navigational system. Volumetric analyses showed that the differences between the metabolic volumes with different CNI thresholds were statistically significant (p < 0.05). For the LGG group, the differences between the structural and the metabolic volumes with CNI thresholds of 0.5 and 1.5 were statistically significant (p = 0.0005 and 0.0129, respectively). For the HGG group, the differences between the structural and metabolic volumes with CNI thresholds of 0.5 and 1.0 were statistically ...