# Frameless robotic stereotactic brain biopsy workflow with CT-MRI fusion and CT-to-fluoroscopy registration: Step-by-step technical note and early experience

## TL;DR

This paper presents a new robot-assisted brain biopsy method using CT-MRI fusion and CT-to-fluoroscopy registration, offering a streamlined and reliable workflow with early success in diagnosis.

## Contribution

A novel, fiducial-free robotic brain biopsy workflow using CT-MRI fusion and CT-to-fluoroscopy registration is introduced and validated.

## Key findings

- CT-to-fluoroscopy registration provided reliable intraoperative anatomical correlation without additional imaging.
- The workflow enabled a conclusive histomolecular diagnosis with no major complications in the initial case.
- Trajectory locking reduced operator variability compared to manual frameless biopsy.

## Abstract

Stereotactic brain biopsy is a widely used procedure for the histopathological and molecular diagnosis of different types of brain lesions. While frame-based techniques remain highly accurate, frameless neuronavigation and robotic platforms have progressively streamlined workflow and standardization. Practical, reproducible registration strategies are key to facilitate safe implementation across centers.

We describe a frameless, robot-assisted stereotactic brain biopsy workflow based on preoperative CT-MRI fusion and intraoperative fiducial-free CT-to-fluoroscopy registration, and report technical considerations for reproducible adoption.

A robot-assisted brain biopsy was performed on a patient with a right frontal butterfly-shaped lesion, based on CT-MRI fusion and CT-to-fluoroscopy “Merge Images” registration. We detail the step-by-step workflow, including the registration strategy, technical advantages and disadvantages, and our initial experience with this protocol.

CT-to-fluoroscopy registration provided reliable intraoperative anatomical correlation and was integrated into the routine setup without intraoperative CT or cone-beam CT. In the index case (and in our early experience), tissue sampling provided a conclusive histomolecular diagnosis, with procedure times consistent with routine stereotactic biopsy practice and no major procedure-related complications.

This technical note outlines a reproducible, step-by-step workflow for robot-assisted stereotactic brain biopsy based on CT-MRI fusion and CT-to-fluoroscopy registration, supported by a standardized operating-room setup. We highlight the practical checkpoints that keep the procedure reliable in routine use, particularly strict fusion verification and uninterrupted optical tracking. Further experience and larger series are warranted to refine its role alongside established stereotactic techniques.

•Micro-burr hole robot-assisted brain biopsy with ExcelsiusGPS.•CT-MRI fusion and CT-to-fluoroscopy registration enable a simple, fiducial-free, streamlined workflow.•Step-by-step workflow using the ExcelsiusGPS “Merge Images” CT-to-fluoroscopy registration.•Early experience supports feasibility: conclusive diagnosis, no major complications, and ∼24-h stay.•Trajectory locking may reduce operator variability compared with manual frameless biopsy.

Micro-burr hole robot-assisted brain biopsy with ExcelsiusGPS.

CT-MRI fusion and CT-to-fluoroscopy registration enable a simple, fiducial-free, streamlined workflow.

Step-by-step workflow using the ExcelsiusGPS “Merge Images” CT-to-fluoroscopy registration.

Early experience supports feasibility: conclusive diagnosis, no major complications, and ∼24-h stay.

Trajectory locking may reduce operator variability compared with manual frameless biopsy.