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

## TL;DR

This study shows that using real-time ultrasound during brain tumor surgery helps remove more of the tumor, especially in larger cases, without increasing complications.

## Contribution

The study demonstrates that 2D intraoperative ultrasound improves resection rates in brain metastasis surgery compared to standard tools.

## Key findings

- IOUS-guided surgery achieved 80% gross total resection compared to 42.86% with standard neuronavigation.
- IOUS increased the odds of achieving GTR by 5.33 times and mitigated the negative effect of larger tumor size.
- Functional outcomes improved postoperatively in both groups, with no increased complications from IOUS.

## Abstract

Brain metastases are a common and serious complication in patients with cancer. Surgery can help relieve symptoms and improve quality of life, especially when the tumor is completely removed. However, standard surgical tools sometimes struggle to show the full extent of the tumor during the operation. This study explores the use of real-time ultrasound imaging during surgery as an additional tool to guide tumor removal. We compared patients who had surgery with ultrasound guidance to those who had conventional surgery using standard navigation tools. Our results showed that ultrasound helped surgeons remove more of the tumor, even in larger cases, without increasing complications. These findings suggest that ultrasound, a low-cost and accessible technique, could help improve surgical outcomes for patients with brain metastases, especially in hospitals with limited resources. This study may encourage wider use of intraoperative ultrasound in brain tumor surgery and support further research on its benefits.

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.