# Focused ultrasound for blood–brain barrier opening in brain tumor patients: Technical nuances

## TL;DR

This paper describes a new optimized protocol for using focused ultrasound to open the blood-brain barrier in brain tumor patients, improving efficiency and patient comfort.

## Contribution

The paper introduces a refined workflow and technical protocol for MR-guided focused ultrasound to enhance blood-brain barrier opening in glioblastoma patients.

## Key findings

- An optimized protocol improved patient comfort and reduced procedure times.
- A 64-spot grid and large treatment envelope enabled near-total brain coverage.
- MRI confirmed successful blood-brain barrier opening without clinical complications.

## Abstract

Focused ultrasound (FUS) is making rapid advances in the field of neurological sciences. While proven effective for tremor, pain and dystonia, FUS hold promises in experimental applications like blood–brain barrier opening (BBBO). BBBO is an emerging non-invasive option for intracranial brain tumor treatments by enhancing drug delivery and enabling liquid biopsies. Clinical trials underscore the need for consistent use of FUS for BBBO, which requires sophisticated facilities and standardized protocols to ensure efficacy and reproducibility. This manuscript outlines a single-center experience using MR-guided FUS (MRgFUS) for BBBO in patients with glioblastoma, incorporating technical insights and describing the evolution of a workflow mirroring an ongoing learning curve.

We developed an optimized protocol that includes comprehensive pre-procedural evaluations, a patient preparation process designed to minimize discomfort, and a sedation protocol utilizing dexmedetomidine, presented as a technical note involving 4 patients. The procedures were conducted using the Exablate Neuro 4000 Type 2 system, with MRI providing precise targeting and monitoring.

Our optimized protocol significantly enhanced patient comfort and reduced procedure times. Employing a large treatment envelope and a 64-spot grid allowed for near-total brain coverage, minimizing the effort for pre-planning and reducing sonication time. Optimized MRI protocol contributed to the reduction in duration and confirmed successful BBBO, indicated by specific imaging signs and the resolution of these effects without any clinical complications.

The protocol we developed for MRgFUS-BBBO offers substantial improvements in terms of procedure efficiency, imaging quality, and patient comfort. This approach could be adopted in other FUS treatment settings to optimize workflows, reduce procedure times, and improve patient outcomes.