Development and evaluation of a new image-based user interface for robot-assisted needle placements with the robopsy system

The main challenges of Computed Tomography (CT)-guided organ puncture are the mental registration of the medical imaging data with the patient anatomy, required when planning a trajectory, and the subsequent precise insertion of a needle along it. An interventional telerobotic system, such as Robopsy, enables precise needle insertion, however, in order to minimize procedure time and number of CT scans, this system should be driven by an interface that is directly integrated with the medical imaging data. In this study we have developed and evaluated such an interface that provides the user with a point-and-click functionality for specifying the desired trajectory, segmenting the needle and automatically calculating the insertion parameters (angles and depth). In order to highlight the advantages of such an interface, we compared robotic-assisted targeting using the old interface (non-image-based) where the path planning was performed on the CT console and transferred manually to the interface with the targeting procedure using the new interface (image-based). We found that the mean procedure time (n=5) was 22±5 min (non-image-based) and 19±1 min (image-based) with a mean number of CT scans of 6±1 (non-image-based) and 5±1 (image-based). Although the targeting experiments were performed in gelatin with homogenous properties our results indicate that an image-based interface can reduce procedure time as well as number of CT scans for percutaneous needle biopsies

MITK-OpenIGTLink for combining open-source toolkits in real-time computer-assisted interventions

PURPOSE: Due to rapid developments in the research areas of medical imaging, medical image processing and robotics, computer-assisted interventions (CAI) are becoming an integral part of modern patient care. From a software engineering point of view, these systems are highly complex and research can benefit greatly from reusing software components. This is supported by a number of open-source toolkits for medical imaging and CAI such as the medical imaging interaction toolkit (MITK), the public software library for ultrasound imaging research (PLUS) and 3D Slicer. An independent inter-toolkit communication such as the open image-guided therapy link (OpenIGTLink) can be used to combine the advantages of these toolkits and enable an easier realization of a clinical CAI workflow. METHODS: MITK-OpenIGTLink is presented as a network interface within MITK that allows easy to use, asynchronous two-way messaging between MITK and clinical devices or other toolkits. Performance and interoperability tests with MITK-OpenIGTLink were carried out considering the whole CAI workflow from data acquisition over processing to visualization. RESULTS: We present how MITK-OpenIGTLink can be applied in different usage scenarios. In performance tests, tracking data were transmitted with a frame rate of up to 1000 Hz and a latency of 2.81 ms. Transmission of images with typical ultrasound (US) and greyscale high-definition (HD) resolutions of [Formula: see text] and [Formula: see text] is possible at up to 512 and 128 Hz, respectively. CONCLUSION: With the integration of OpenIGTLink into MITK, this protocol is now supported by all established open-source toolkits in the field. This eases interoperability between MITK and toolkits such as PLUS or 3D Slicer and facilitates cross-toolkit research collaborations. MITK and its submodule MITK-OpenIGTLink are provided open source under a BSD-style licence ( http://mitk.org

Tattoo tomography: Freehand 3D photoacoustic image reconstruction with an optical pattern

Purpose!#!Photoacoustic tomography (PAT) is a novel imaging technique that can spatially resolve both morphological and functional tissue properties, such as vessel topology and tissue oxygenation. While this capacity makes PAT a promising modality for the diagnosis, treatment, and follow-up of various diseases, a current drawback is the limited field of view provided by the conventionally applied 2D probes.!##!Methods!#!In this paper, we present a novel approach to 3D reconstruction of PAT data (Tattoo tomography) that does not require an external tracking system and can smoothly be integrated into clinical workflows. It is based on an optical pattern placed on the region of interest prior to image acquisition. This pattern is designed in a way that a single tomographic image of it enables the recovery of the probe pose relative to the coordinate system of the pattern, which serves as a global coordinate system for image compounding.!##!Results!#!To investigate the feasibility of Tattoo tomography, we assessed the quality of 3D image reconstruction with experimental phantom data and in vivo forearm data. The results obtained with our prototype indicate that the Tattoo method enables the accurate and precise 3D reconstruction of PAT data and may be better suited for this task than the baseline method using optical tracking.!##!Conclusions!#!In contrast to previous approaches to 3D ultrasound (US) or PAT reconstruction, the Tattoo approach neither requires complex external hardware nor training data acquired for a specific application. It could thus become a valuable tool for clinical freehand PAT

Human vs. robot operator error in a needle-based navigation system for percutaneous liver interventions

Computed tomography (CT) guided percutaneous punctures of the liver for cancer diagnosis and therapy (e.g. tumor biopsy, radiofrequency ablation) are well-established procedures in clinical routine. One of the main challenges related to these interventions is the accurate placement of the needle within the lesion. Several navigation concepts have been introduced to compensate for organ shift and deformation in real-time, yet, the operator error remains an important factor influencing the overall accuracy of the developed systems. The aim of this study was to investigate whether the operator error and, thus, the overall insertion error of an existing navigation system could be further reduced by replacing the user with the medical robot Robopsy. For this purpose, we performed navigated needle insertions in a static abdominal phantom as well as in a respiratory liver motion simulator and compared the human operator error with the targeting error performed by the robot. According to the results, the Robopsy driven needle insertion system is able to more accurately align the needle and insert it along its axis compared to a human operator. Integration of the robot into the current navigation system could thus improve targeting accuracy in clinical use.German Research Foundation (DFG