2D Intraoperative Ultrasound in Brain Metastasis Resection: A Matched Cohort Analysis from a Single-Center Experience

Background: Intraoperative ultrasound (IOUS) provides real-time imaging during brain tumor surgery but remains underused in brain metastasis resection. This study evaluates the effectiveness of 2D IOUS in improving the extent of resection compared to standard neuronavigation. Methods: We retrospectively analyzed 55 adult patients with brain metastases treated surgically at a single center. Patients were divided into two groups: IOUS-guided surgery (n = 20) and standard neuronavigation (n = 35). Gross total resection (GTR) was defined as the extent of resection > 96%, assessed volumetrically. Statistical analyses included chi-square tests, logistic regression, and ROC curve analysis. Results: GTR > 96% was achieved in 80% of IOUS-guided cases compared to 42.86% in the control group (p = 0.008). IOUS significantly increased the odds of achieving GTR (OR = 5.33, p = 0.011). Larger tumor volume reduced the likelihood of GTR (OR = 0.469, p = 0.025), but this effect was mitigated by IOUS use (interaction OR = 1.986, p = 0.044). The regression model showed excellent discrimination (AUC = 0.930, p < 0.001). Functional outcomes improved postoperatively in both groups. Conclusions: 2D IOUS significantly enhances the extent of resection in brain metastasis surgery, including that for larger tumors. Its accessibility, real-time feedback, and low cost support its wider adoption in neurosurgical practice, especially in settings with limited resources.