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10:30   Medical Instruments I Chair: John van den Dobbelsteen 10:30 15 mins EVALUATION OF MANUAL NEEDLE STEERING UNDER IMAGE GUIDANCE Nick van de Berg, Jenny Dankelman, John van den Dobbelsteen Abstract: Introduction: Needles play an important role in the diagnosis and treatment of liver cancer. However, undesired needle deflections have been regularly reported. In addition, in some cases, the lesion cannot be accessed in a straight line due to intermediate structures, such as the ribs and lungs. Needle steering has been studied as a method to allow for direct access to inconveniently seated lesions, as well as to correct for errors caused by needle deflections. So far, developed prototypes have been examined in a robotic or automated fashion. In contrast, the current study evaluates the manual use of a steerable needle to reach off-axis targets. Method: The needle consists of a cannula, and a retractable stylet. The conical instrument tip is positioned adjacent to a flexure joint, allowing for tip articulations of max. 10° to any desired direction. Needles were manually inserted in 8 wt.% gelatin and their paths were tracked with a camera (FL3-U3-13E4C-C, Point Grey, CA). During the insertion, the cannula is expected to deflect in the direction of the tip. Manual steering was evaluated in five principal directions, respectively left, right, front, back, and central. Targets in these steering directions were randomly assigned to the experimental runs (N=50). The targets were located at a depth of 100 mm, 20 mm lateral of the vertical insertion line (except for the central target, which was located on this line). To encourage active instrument use, it was ensured that the targets would not be reached by means of the maximum tip articulation angle. The participant used a real-time visual display from the camera for steering. The paths were stored and analysed to determine 1) the steering precision (S.D.), 2) the mean absolute error with respect to the target, and 3) the tip articulation angles. Results: The overall precision in tip-placement (S.D.) during the manual insertion task was 1.1 mm. The systematic (mean, absolute) error from the set target locations was 0.5 mm. The tip angles varied largely among experimental runs. They showed, on average, a convergence to zero, suggesting that the need for steering slowly reduced with insertion depth, i.e. while the tip and target gradually aligned. Discussion: The small systematic error illustrates that the participant was able to manually steer the needle in any of the required directions. There was no notable bias or directional preference in device control. Occasionally, insufficient steering was achieved at the start of the insertion, resulting in errors larger than 1 mm. Oversteering rarely occurred as this would be observed from the visual feedback and could be timely compensated for. In two out of five steering directions, the final tip angle was, on average, oriented in the reverse direction as the overall needle curve. This suggests the presence of an s-curve in the needle path. Conclusion: This study illustrates the possibility to operate a manually controlled, tip articulated needle in a simulant tissue under image guidance. 10:45 15 mins DESIGN AND IMPLEMENTATION OF AUTONOMOUS ROBOTIC SCANNING OF THE BREAST Judith Schoot Uiterkamp, Vincent Groenhuis, Françoise Siepel, Stefano Stramigioli Abstract: Breast cancer is the most common type of cancer in women worldwide, with nearly 1.7 million new cases diagnosed in 2012.[1] Improvement of breast biopsy methods, allowing early detection and reliable diagnosis, can reduce the mortality rate significantly.[2] The MURAB project stands for MRI and Ultrasound Robotic Assisted Biopsy and aims to improve breast biopsy. Image modalities such as ultrasound and MRI are used to locate the lesion. MRI breast biopsy provides higher resolution images but is significantly more complicated than ultrasound guided biopsy and causes increased discomfort for the patient and increased intervention time and costs. The MURAB project aims to reduce these drawbacks using the advantages of both imaging modalities. Images of both modalities will be registered and will provide input during the robotic assisted biopsy while using real-time ultrasound guidance to guide the biopsy needle to the lesion. The main aim of this research project is to design and implement the ultrasound scanning phase during which the breast of the patient is autonomously scanned by a LWR4+ lightweight robotic arm (KUKA industrial robots, Germany) in order to acquire 2D ultrasound images. The design and implementation in this study consists of 1) autonomous initialization of scanning using visual servoing, 2) automatic trajectory planning and 3) contact control using force feed-back to maintain a constant contact pressure between the robot probe and the patient while keeping the probe normal to the breast surface. Experiments were performed using breast phantoms. Results showed that during initialization of the scanning motion the robot is steered to the correct start position with an accuracy of 1.6 mm. It was possible to automatically plan the trajectory, after which the robotic arm made contact with the breast phantom. The contact pressure of 5N was maintained during the full scan and the probe was kept normal to the surface with an average deviation of seven degrees. These results are promising for further implementation and fine tuning of the scanning phase using a robot arm designed for breast biopsy applications. The MURAB project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 688188. References [1] World Cancer Research Fund International (2012), Breast cancer statistics. http://www.wcrf.org/int/cancer-facts-figures/ data-specific-cancers/breast-cancer-statistics [2] Khatib, Oussama MN, and Atord Modjtabai. "Guidelines for the early detection and screening of breast cancer." World Health Organization. Technical Publications Series 30 (2006). 11:00 15 mins DESIGN AND EVALUATION OF A ROBOTIC NEEDLE STEERING MANIPULATOR FOR IMAGE-GUIDED BREAST BIOPSY Ruud Spoor, Momen Abayazid, Vincent Groenhuis, Françoise Siepel, Stefano Stramigioli Abstract: Breast cancer is one of the leading causes of cancer death in women. First signs of breast cancer are often found during the screening phase. In this phase, the breast is examined using screening techniques such as manual palpation, mammography, ultrasound and Magnetic Resonance Imaging (MRI). Suspected regions are further investigated by inserting a biopsy needle where imaging modalities such as MRI and ultrasound are used for guidance to target the lesion to acquire tissue samples for pathology assessment. As needle biopsy under MRI guidance is difficult due to the limited amount of space inside the MRI scanner and sensitivity to ferro-magnetic materials, ultrasound-guided biopsy is often the method of choice, due real-time, availability and lower cost advantages. However, ultrasound detectability of tumors is still lower than that of MRI. This study is part of a project aiming to combine both MRI and ultrasound imaging worlds for precise robotic-assisted needle biopsy. An off-the-shelf robotic arm from KUKA (Munich, Germany) is used to steer an ultrasound probe [1][2] and needle guide end-effector. After localization of targeted lesion with the ultrasound transducer and merged MRI data, a needle guide is placed into the target position with the use of mechatronics. For Safety reasons, a biopsy needle is manually inserted through the guide into the breast by a radiologist [3]. The aim of this research is to design and evaluate an end-effector (Figure 1) to be mounted on a robotic arm. This end-effector is composed of an ultrasound probe holder and the needle-guide. The base of the end-effector interconnects motors, probe holder and robot interface to each other, Six set screws are used to clamp and align an ultrasound probe with the needle guide so that the controlled planar movement of the needle is visible in the ultrasound image plane. The needle guide is mechatronically manipulated through a parallel mechanism that is laser cut out of delrin parts. With the help of magnetic joints, the biopsy needle is released from its holder for safety when applied forces are higher than 1.5N. This was validated with spring scale measurements. Workspace analysis showed that the needle and guiding mechanism can handle breast sizes with diameters up to 200mm, measured from the base of the breast. A preliminary hazard analysis was performed and the design evaluation on a breast phantom showed that the end-effector is expected to provide safe insertion of the biopsy needle. The robotic arm provides more precise positioning of the needle on the breast surface. This helps in reducing the needle insertion path length in breast tissue and consequently minimizes the patient’s trauma. Based on the obtained results, further development of the current end-effector (prototype) is expected to result in a functional product. Validation of the end-effector developed in current study showed promising results for biopsy procedures. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 688188. 11:15 15 mins Needle Insertions in Ex-Vivo Human Cirrhotic Liver Tonke de Jong, Dennis van Gerwen, Adriaan Moelker, Jan IJzermans, Jenny Dankelman, John van den Dobbelsteen Abstract: Introduction: Steerable needles and robotic positioning systems are possible technical tools to improve needle placement accuracy in radiologic interventions. Experimental data on needle-tissue interaction are important for their clinical development, but scarce. Therefore, the aim of this research is to characterize the insertion forces when inserting needles into fresh cirrhotic liver tissue and to analyse the needle insertion path. In this study, a pilot experiment was carried out, using one ex-vivo cirrhotic human liver. Methods: A needle insertion set-up was developed for this experiment. It consisted of a linear mini slide that was mounted vertically with respect to the table. The base of the needle tip was aligned with an ultrasound transducer (out of plane), whereas the hub of the needle was connected with a load sensor. A fresh cirrhotic liver was extracted from a patient that underwent transplantation surgery and immediately used for the experiment after extraction. The complete liver was placed vertically, to simulate right percutaneous needle access, in a custom-made soft transparent PVC container filled with silicone material. Liver hardness was estimated using a Shore OO durometer, by 3 repeated measurements at 10 random locations on the liver surface, before and after the needle insertion experiment. The pilot experiment consisted of multiple needle insertions into the liver, while tracking the insertion path with the ultrasound machine and capturing the forces with the load sensor. In total, 4 different needle types were used: 18 and 21 Gauge Trocar needles and 18 and 21 Gauge Chiba needles. Results: Higher maximum forces were registered for the 18G needles compared with 21G, respectively 3N and 2N. Peaks in the force data were found for all insertions. No difference in liver hardness was found before (38.2±9.3) and after (38.8±7.8) the needle insertions. Needle deflection was observed for all insertions. Discussion & conclusion: In this study, a pilot experiment was carried out, regarding the insertion of needles into fresh cirrhotic human liver, obtained from a patient that underwent transplantation surgery. Future work includes the examination of multiple livers, aiming to collect a bigger data-set on insertion forces and needle deflection in diseased human livers. This data-set can be used for setting up clinically relevant design requirements for supporting robotic systems and steerable needles, with the goal to improve needle placement in radiologic interventions. 11:30 15 mins MRI-GUIDED FLEXIBLE NEEDLE STEERING USING FIBER BRAGG GRATING-BASED TIP TRACKING Pedro Moreira, Sarthak Misra Abstract: This work presents a flexible needle steering system that combines the MIRIAM robot and a needle tip tracker based on Fiber Bragg Grating (FBG) sensors. The MIRIAM robot is an MR-compatible robot that combines piezoelectric and pneumatic actuation methods to achieve precise prostate interventions. The pre-operative MR images are used to localize obstacles and targets, while the FBG sensors provide strain measurements used to estimate the needle tip position and the force applied at the needle base during the insertion. The experiments are performed with a flexible bevel-tipped Nitinol needle integrated with an array of 12 FBG sensors, located along three optical fibers. 11:45 15 mins 3D MODEL OF GUIDEWIRE MOTION BASED ON ITS MECHANICAL PROPERTIES Hoda Sharei, John van den Dobbelsteen, Jenny Dankelman Abstract: Introduction: Guidewire and catheter modelling is an emerging research area and a variety of techniques have been used for simulation [1-4]. Although there are different types of these simulators, they are mainly for training purposes. In this paper, we present a computer-based model to simulate the behaviour of a guidewire in blood vessels. However, our main objective is to find ways of improving the choice of guidewire prior to the procedure. Up until now, there is no metric to select an appropriate one for a patient with a specific vessel geometry. Thus, the selection is mainly based on interventional cardiologist’s experience and is subjective rather than objective. Preoperative modelling of the interactions of the guidewire within the vasculature could support the user in selecting the guidewires with suitable mechanical properties for successful navigation. Method: In our model, the guidewire is considered as a discrete body: n interconnected rigid bodies, each of which may translate and rotate. To account for the bending stiffness of the guidewire, joints with torsional springs, and dampers are located at each interconnection. To obtain real data regarding the stiffness, 3-point bending tests were performed. Different types of guidewires, including stiff guidewires and micro-guidewires, were included in the study. We have modelled the guidewire both by driving the equations of motion for 2D and by use of Simscape™ Multibody™ for 3D (which is a multibody simulation environment). Results & Discussion: In this study, we have developed a guidewire model and have endeavoured to investigate the motion behaviour in different vascular geometry and the importance of guidewire’s mechanical properties on the motion. Use of such simulations enables the user to assess the possible motions, and even to predict the success rate of the PCI (Percutaneous coronary intervention). ACKNOWLEDGMENT This work is part of the research program CONNECT project within the research program interactive Multi-Interventional Tools (iMIT), which is supported by the Dutch Technology Foundation STW (which is part of the Netherlands Organization for Scientific Research (NWO)). REFERENCES [1] Konings, M.K., Van de Kraats, E.B., Alderliesten, T. and Niessen, W.J., 2003. Analytical guide wire motion algorithm for simulation of endovascular interventions. Medical and Biological Engineering and Computing, 41(6), pp.689-700. [2] Takashima, K., Tsuzuki, S., Ooike, A., Yoshinaka, K., Yu, K., Ohta, M. and Mori, K., 2014. Numerical analysis and experimental observation of guidewire motion in a blood vessel model. Medical engineering and physics, 36(12), pp.1672-1683. [3] El-Khalili, Nuha H. ”Surgical Training on the World Wide Web.” PhD diss., The University of Leeds, 1999. [4] Vincent Guilloux, Pascal Haigron, Cemil Goksu, Carine Kulik, Antoine Lucas, ”Simulation of guidewire navigation in complex vascular structures”, Proc. SPIE 6141, Medical Imaging 2006.