In closed-bore MRI units, assistance systems play a crucial role in overcoming patient access limitations during percutaneous interventions. In this work, we present eGantryMate, a piezo-motor-driven assistance system specifically designed for MR-guided needle interventions in high-field MRI systems. eGantryMate consists of an instrument positioning unit and a control unit equipped with piezo motors, radiofrequency filters, and shielding. Paired with a real-time tracking sequence for automatic marker detection and projection of the instrument trajectory onto the MR image, eGantryMate enables precise and efficient needle interventions. Targeting experiments were performed by inserting a biopsy needle into a series of fiducial targets in a phantom, and usability experiments were conducted in vivo without needle insertion. The results show artifact-free MR imaging, minimal temperature rise on the instrument positioning unit, and precise targeting capabilities. These findings demonstrate eGantryMate’s ability to perform real-time needle alignments and insertions within the magnet bore, highlighting its potential to enhance the acceptability and efficacy of MR-guided interventions.

Percutaneous minimally invasive interventions are difficult to perform in closed-bore high-field magnetic resonance systems owing to the limited space between magnet and patient. To enable magnetic resonance–guided needle interventions, we combine a small, patient-mounted assistance system with a real-time instrument tracking sequence based on a phase-only cross-correlation algorithm for marker detection. The assistance system uses 2 movable plates to align an external passive marker with the anatomical target structure. The targeting accuracy is measured in phantom experiments, yielding a precision of 1.7 ± 1.0 mm for target depths up to 38 ± 13 mm. In in vivo experiments, the possibility to track and target static and moving structures is demonstrated.

There is no real need to discuss the potential advantages - mainly the excellent soft tissue contrast, nonionizing radiation, flow, and molecular information - of magnetic resonance imaging (MRI) as an intraoperative diagnosis and therapy system particularly for neurological applications and oncological therapies. Difficult patient access in conventional horizontal-field superconductive magnets, very high investment and operational expenses, and the need for special nonferromagnetic therapy tools have however prevented the widespread use of MRI as imaging and guidance tool for therapy purposes. The interventional use of MRI systems follows for the last 20+ years the strategy to use standard diagnostic systems and add more or less complicated and expensive components (eg, MRI-compatible robotic systems, specially shielded in-room monitors, dedicated tools and devices made from low-susceptibility materials, etc) to overcome the difficulties in the therapy process. We are proposing to rethink that approach using an in-room portable ultrasound (US) system that can be safely operated till 1 m away from the opening of a 3T imaging system. The live US images can be tracked using an optical inside-out approach adding a camera to the US probe in combination with optical reference markers to allow direct fusion with the MRI images inside the MRI suite. This leads to a comfortable US-guided intervention and excellent patient access directly on the MRI patient bed. This was combined with an entirely mechanical MRI-compatible 7 degrees of freedom holding arm concept, which shows that this test environment is a different way to create a cost-efficient and effective setup that combines the advantages of MRI and US by largely avoiding the drawbacks of current interventional MRI concepts.

Submillimetric precision is essential for stereotactic neurosurgical procedures. However, accuracy of standard neurosurgical procedures such as navigated biopsies and shunts is currently limited due to manual alignment of the biopsy needle or manual placement of the shunt catheter. The aim of this study is to evaluate the feasibility and accuracy of a novel robotic positioning device for stereotactic neurosurgical procedures. We conducted a preclinical phantom trial to evaluate the accuracy of the iSYS1 robotic device in a representative stereotactic neurosurgical procedure: Robotic guidance of a biopsy needle was compared to standard manual needle trajectory alignment. Biopsies were performed by 7 neurosurgeons of different levels of experience either with robotic trajectory alignment (n=81) or manual alignment using a standard mechanical biopsy arm (n=81) under navigational guidance (Medtronic StealthStation S7). The paper describes the setup, the test methodology as well as the achieved results.

Perkutane Nadelprozeduren haben sich zu wichtigen medizinischen Verfahren in Diagnostik und Therapie entwickelt. Zu den gebräuchlichsten Anwendungen gehören die Gewebsentnahme für diagnostische Zwecke (Biopsie) sowie Behandlungsmethoden wie RF-Ablation, Kryo-Ablation, Schmerzbehandlung, Drainagen und andere. Da es während der Platzierung des Werkzeugs – also der Nadel — keinen direkten Sichtkontakt zum Zielbereich gibt, werden diese Verfahren durch präund/oder intra-operative Bildgebung unterstützt. Dieser Bericht beschreibt die Kombination einer neuartigen Roboter-Zielvorrichtung mit dem bildgebenden Verfahren der "Cone-Beam-Computertomographie" (CBCT). Der Schwerpunkt des Artikels liegt auf dem entwickelten Work-Flow für eine nahtlose Integration des Robotersystems in die klinische Umgebung. Ebenso werden Ergebnisse einer ersten multizentrischen Evaluationsstudie dargestellt. Schlüsselworte: Medizin-Robotik, bildgestüzte Diagnose und Therapie, interventionelle Radiologie

Abstract Background To introduce a novel method of patient positioning for high precision intracranial radiotherapy. Methods An infrared(IR)-array, reproducibly attached to the patient via a vacuum-mouthpiece(vMP) and connected to the table via a 6 degree-of-freedom(DoF) mechanical arm serves as positioning and fixation system. After IR-based manual prepositioning to rough treatment position and fixation of the mechanical arm, a cone-beam CT(CBCT) is performed. A robotic 6 DoF treatment couch (HexaPOD™) then automatically corrects all remaining translations and rotations. This absolute position of infrared markers at the first fraction acts as reference for the following fractions where patients are manually prepositioned to within ± 2 mm and ± 2° of this IR reference position prior to final HexaPOD-based correction; consequently CBCT imaging is only required once at the first treatment fraction. The preclinical feasibility and attainable repositioning accuracy of this method was evaluated on a phantom and human volunteers as was the clinical efficacy on 7 pilot study patients. Results Phantom and volunteer manual IR-based prepositioning to within ± 2 mm and ± 2° in 6DoF was possible within a mean(± SD) of 90 ± 31 and 56 ± 22 seconds respectively. Mean phantom translational and rotational precision after 6 DoF corrections by the HexaPOD was 0.2 ± 0.2 mm and 0.7 ± 0.8° respectively. For the actual patient collective, the mean 3D vector for inter-treatment repositioning accuracy (n = 102) was 1.6 ± 0.8 mm while intra-fraction movement (n = 110) was 0.6 ± 0.4 mm. Conclusions This novel semi-automatic 6DoF IR-based system has been shown to compare favourably with existing non-invasive intracranial repeat fixation systems with respect to handling, reproducibility and, more importantly, intra-fraction rigidity. Some advantages are full cranial positioning flexibility for single and fractionated IGRT treatments and possibly increased patient comfort.

Background: To introduce a novel method of patient positioning for high precision intracranial radiotherapy. Methods: An infrared(IR)-array, reproducibly attached to the patient via a vacuum-mouthpiece(vMP) and connected to the table via a 6 degree-of-freedom(DoF) mechanical arm serves as positioning and fixation system. After IR-based manual prepositioning to rough treatment position and fixation of the mechanical arm, a cone-beam CT(CBCT) is performed. A robotic 6 DoF treatment couch (HexaPOD™) then automatically corrects all remaining translations and rotations. This absolute position of infrared markers at the first fraction acts as reference for the following fractions where patients are manually prepositioned to within ± 2 mm and ± 2° of this IR reference position prior to final HexaPOD-based correction; consequently CBCT imaging is only required once at the first treatment fraction.

The appropriateness of robotic systems for interventional radiology could be successfully demonstrated by our previous prototype “B-RobI” as well as by other groups. Such robotic targeting devices can serve as the physician's “third hand” providing with a stable and accurate guidance of the medical tool–e.g. a biopsy needle–towards the lesion. For integration of such new technology into clinical practice, robotic systems must be further improved in terms of safety, reliability and easy handling. This paper describes a new design for a robotic targeting device, which is aimed to transfer the proofed concepts from our prototype “B-RobI” into a practical clinical setup. The paper outlines the system modules and a first in vitro study for US-guided biopsies using a needle penetrable phantom.

To demonstrate why conventional non-invasive mouthpiece-based fixation has not achieved the expected accuracy and to suggest a solution of the problem.

Die fraktionierte interstitielle Brachytherapie mit Nadeln von Tumoren im HNO-Bereich erfordert eine exakte Lokalisierung des Zielgewebes bei allen Bestrahlungsfraktionen. Eine wichtige Voraussetzung hier für ist die Reproduzierbarkeit der Positionierung der Nadel(n).

Um die Möglichkeit der Bestrahlungsplanung von Kopf-Hals-Tumoren voll ausschöpfen zu können, ist eine exakte, reproduzierbare Kopffixation Grundvoraussetzung.

A real-time sequence is presented with automatic adjustment of the imaging plane parallel to a needle. The sequence utilizes the phase-only cross correlation (POCC) algorithm to detect the orientation of an end-effector and to visualize the planned needle pathway. Additionally, it detects a passive marker at the distal end of the needle to calculate the position of the needle tip for real-time display during needle insertion. The sequence is evaluated in a phantom experiment, and both lateral and longitudinal needle insertion accuracies are determined.

We present a small and flexible piezo-driven assistance system, which can be steered from outside the magnet bore via a control unit. The assistance system is combined with a tracking sequence, which is able to follow in-bore manipulations of a dedicated end effector in real-time. For an initial evaluation, the assistance systems is equipped with a biopsy needle and targeting experiments are performed in a phantom setting.

Motivation: MR-guided percutaneous interventions at closed-bore high-field systems profit from remote device manipulation with real-time needle tracking. Goal(s): To integrate a sequence capable of acquiring two T2-weighted orthogonal slices simultaneously (Ortho-SSFP-Echo) into the device-assisted needle intervention workflow during needle insertion. Approach: The assistance system (GantryMate) was coupled with a real-time POCC sequence to target a lesion. Once the lesion was identified, its position information was used in a real-time Ortho-SSFP-Echo acquisition to dynamically monitor the needle insertion. Results: The Ortho-SSFP-Echo sequence enables simultaneous needle visualization in two planes, offering higher CNR than GRE and comparable to bSSFP, without banding artifacts. Impact: Combining an Ortho-SSFP-Echo sequence with a compact needle assistance system provides a streamlined interventional workflow with decreased complexity and improved image contrast for MR-guided percutaneous interventions at high field.