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The technique of ultrasound-guided needle insertion is commonly employed in various clinical fields, including biopsy, anesthesia, brachytherapy, and ablation. However, the visibility of the needle in ultrasound (US) images remains a persistent challenge. To improve the guidance accuracy of needle insertion during interventions, it is crucial to develop a reliable technique that enhances the visibility of ultrasound needles and accurately detects their position and orientation. Recently, Deep Learning (DL) based segmentation methods have drawn attention because of their high efficiency and accurate results. In order to improve the model performance on challenging datasets, previous researchers modified the segmentation models by introducing spatial attention mechanism and temporal information. However, whether the approaches are effective for ultrasound images, especially for the needle insertion tasks remains unclear. This thesis aims to investigate whether deep learning models are able to increase segmentation accuracy as well as localization accuracy in 2D ultrasound images, specifically focusing on introducing spatial attention and optical flow information into U-Net backbone. Spatial Mask Attention U-Net (SMA-UNet) and Optical Flow Attention U-Net (OFA-UNet) were therefore proposed. The hierarchical experiments were designed to evaluate the effects of training loss, mask width and optical flow methods, and then select an optimal configuration for the segmentation models. Furthermore, U-Net, Attention U-Net and two proposed models were validated on datasets collected from pork and beef phantoms, as well as patients. The evaluation results indicate that OFA-UNet has significant improvement in terms of segmentation metrics and geometrical errors compared to the U-Net baseline and the U-Net only considering the mask attention. Specifically, the model achieved Dice of 86.7%, IoU of 88.2%, Precision of 88.6%, tip error of 2.7 mm and angular error of 0.002 ra, Mechanical Engineering | BioMechanical Design

Breast cancer is currently the most prevalent type of cancer. The concluding diagnosis can be obtained with an MRI-guided biopsy. However, due to respiratory movement and human error, the procedure can require multiple attempts, resulting in harmful consequences. To reach the target at the first attempt, the precision of the procedure should be increased, and a robotic system can aid in this. An MRI-compatible concept is designed, but two of its working principles need to be researched before further development. A possible solution for increasing precision is rotating the needle along the insertion axis. Literature has studied the effect rotation has on insertion force, tissue indentation and target displacement in axial direction, which all show a decrease. However, the effect of rotation on the needle end-point position in lateral direction is not yet researched, and this is a good indication of targeting precision. Therefore, this work has studied the effect of rotation on the precision of the needle end-point position in lateral direction. The concept uses pneumatically actuated stepper motors for the needle insertion. As the air will be supplied from outside the MRI room, the maximum frequency of air supply is estimated at 10 Hz. Therefore, the effect of an actuation frequency of 10 Hz on the precision of the needle end-point position in lateral direction is studied as well. Both effects are researched by inserting a needle in a gelatin phantom at different angular velocities and at continuous versus discrete actuation. It is found that rotation significantly decreases the standard deviation in 6 of the 12 cases. The actuation frequency of 10 Hz does not significantly increase the standard deviation in 7 of the 8 cases. These results can be used to further increase the precision of a biopsy robot, whether it is for breast biopsy or another application., Mechanical Engineering

Breast cancer is currently the most prevalent type of cancer. The concluding diagnosis can be obtained with an MRI-guided biopsy. However, due to respiratory movement and human error, the procedure can require multiple attempts, resulting in harmful consequences. To reach the target at the first attempt, the precision of the procedure should be increased, and a robotic system can aid in this. An MRI-compatible concept is designed, but two of its working principles need to be researched before further development. A possible solution for increasing precision is rotating the needle along the insertion axis. Literature has studied the effect rotation has on insertion force, tissue indentation and target displacement in axial direction, which all show a decrease. However, the effect of rotation on the needle end-point position in lateral direction is not yet researched, and this is a good indication of targeting precision. Therefore, this work has studied the effect of rotation on the precision of the needle end-point position in lateral direction. The concept uses pneumatically actuated stepper motors for the needle insertion. As the air will be supplied from outside the MRI room, the maximum frequency of air supply is estimated at 10 Hz. Therefore, the effect of an actuation frequency of 10 Hz on the precision of the needle end-point position in lateral direction is studied as well. Both effects are researched by inserting a needle in a gelatin phantom at different angular velocities and at continuous versus discrete actuation. It is found that rotation significantly decreases the standard deviation in 6 of the 12 cases. The actuation frequency of 10 Hz does not significantly increase the standard deviation in 7 of the 8 cases. These results can be used to further increase the precision of a biopsy robot, whether it is for breast biopsy or another application., Mechanical Engineering

peer-reviewed, The full text of this article will not be available in ULIR until the embargo expires on the 22/06/2020, This is a pre-print of an article that was published in " Computers In Biology And Medicine" for the final version please see http://dx.doi.org/10.1016/j.compbiomed.2019.103337, Planning and practice of surgical procedures can be improved through the use of modelling. This study provides an insight into the biopsy needle (i.e. hollow cannula) and needle-tissue interactions using a modelling approach, thus enabling the optimization of needle-tip designs not only for training but also for the planning of surgical procedures. Simulations of needle insertion into agar gel were performed using a Coupled Eulerian-Lagrangian (CEL) based finite element (FE) analysis, adapted for large deformation and tissue fracture. The experimental work covers needle insertion into 3% agar gel using a needle with a beveled tip of various angles, to assess the validity of the simulation. The simulated needle deflection and insertion force for two needles (i.e. Needle 1 with 18° bevel angle and Needle 2 with 27° bevel angle) were compared with corresponding experimental results. The contact stress (i.e. contact pressure) on the needles from the agar gel during the insertion of the needles were also studied. Observations indicate that varying the needle bevel angle from 27° to 18° results in a decrease of the peak force (i.e. puncture force) and an increase in needle deflection. Quantitatively, the percentage errors between the experimental data and the FE model for the total insertion force along the z-direction (i.e. Z Force) for Needle 1 and 2 were 4% and 4.8% (p > 0.05), respectively. Similarly, needle deflection percentage errors along the x-z plane were 5.7% and 10% respectively. Therefore, the forces and needle deflection values predicted by the simulation are a close approximation of the experimental model, validating the Coupled Eulerian-Lagrangian based FE model. Thus, providing an experimentally validated model for biopsy and cytology needle design in silico that has the potential to replace the current build and break approach of needle design used by manufacturers., peer-reviewed

Convection-enhanced delivery (CED) is a promising method to deliver therapeutic drugs directly into the brain that has shown limited efficacy, mainly attributed to backflow, in which the infused drug flows back along the needle track rather than forward into tissue. This study evaluates the effect of sharp and blunt needle tips on backflow length under different flow rates via CED. Infusions were performed in a transparent 0.6% (w/v) brain phantom agarose hydrogel. Backflow length was significantly higher using sharp-tip needles for higher flow rates. No significant differences were observed between tip shapes for lower flow rates. In conclusion, sharp-tip needles present limitations for higher flow rates, which are needed to deliver more drug during shortest times.

Convection-enhanced delivery (CED) is a promising method to deliver therapeutic drugs directly into the brain that has shown limited efficacy, mainly attributed to backflow, in which the infused drug flows back along the needle track rather than forward into tissue. This study evaluates the effect of sharp and blunt needle tips on backflow length under different flow rates via CED. Infusions were performed in a transparent 0.6% (w/v) brain phantom agarose hydrogel. Backflow length was significantly higher using sharp-tip needles for higher flow rates. No significant differences were observed between tip shapes for lower flow rates. In conclusion, sharp-tip needles present limitations for higher flow rates, which are needed to deliver more drug during shortest times.

We present the corotational cut Finite Element Method (FEM) for real-time surgical simulation. The only requirement of the proposed method is a background mesh, which is not necessarily conforming to the boundaries/interfaces of the simulated object. The details of the surface, which can be directly obtained from binary images, are taken into account by a multilevel embedding algorithm which is applied to elements of the background mesh that are cut by the surface. Dirichlet boundary conditions can be implicitly imposed on the surface using Lagrange multipliers, whereas traction or Neumann boundary conditions, which is/are applied on parts of the surface, can be distributed to the background nodes using shape functions. The implementation is verified by convergences studies, of the geometry and of numerical solutions, which exhibit optimal rates. To verify the reliability of the method, it is applied to various needle insertion simulations (e.g. for biopsy or brachytherapy) into brain and liver models. The numerical results show that, while retaining the accuracy of the standard FEM, the proposed method can (1) make the discretisation independent from geometric description, (2) avoid the complexity of mesh generation for complex geometries, and (3) provide computational speed suitable for real-time simulations. Thereby, the proposed method is very suitable for patient-specific simulations as it improves the simulation accuracy by automatically, and properly, taking the simulated geometry into account, while keeping the low computational cost.

We present the corotational cut Finite Element Method (FEM) for real-time surgical simulation. The only requirement of the proposed method is a background mesh, which is not necessarily conforming to the boundaries/interfaces of the simulated object. The details of the surface, which can be directly obtained from binary images, are taken into account by a multilevel embedding algorithm which is applied to elements of the background mesh that are cut by the surface. Dirichlet boundary conditions can be implicitly imposed on the surface using Lagrange multipliers, whereas traction or Neumann boundary conditions, which is/are applied on parts of the surface, can be distributed to the background nodes using shape functions. The implementation is verified by convergences studies, of the geometry and of numerical solutions, which exhibit optimal rates. To verify the reliability of the method, it is applied to various needle insertion simulations (e.g. for biopsy or brachytherapy) into brain and liver models. The numerical results show that, while retaining the accuracy of the standard FEM, the proposed method can (1) make the discretisation independent from geometric description, (2) avoid the complexity of mesh generation for complex geometries, and (3) provide computational speed suitable for real-time simulations. Thereby, the proposed method is very suitable for patient-specific simulations as it improves the simulation accuracy by automatically, and properly, taking the simulated geometry into account, while keeping the low computational cost.

Yamaguchi S., Tsutsui K., Satake K., et al. Dynamic analysis of a needle insertion for soft materials: Arbitrary Lagrangian-Eulerian-based three-dimensional finite element analysis. Computers in Biology and Medicine 53, 42 (2014); https://doi.org/10.1016/j.compbiomed.2014.07.012., Background: Our goal was to develop a three-dimensional finite element model that enables dynamic analysis of needle insertion for soft materials. To demonstrate large deformation and fracture, we used the arbitrary Lagrangian-Eulerian (ALE) method for fluid analysis. We performed ALE-based finite element analysis for 3% agar gel and three types of copper needle with bevel tips. Methods: To evaluate simulation results, we compared the needle deflection and insertion force with corresponding experimental results acquired with a uniaxial manipulator. We studied the shear stress distribution of agar gel on various time scales. Results: For 30°, 45°, and 60°, differences in deflections of each needle between both sets of results were 2.424, 2.981, and 3.737. mm, respectively. For the insertion force, there was no significant difference for mismatching area error (p<0.05) between simulation and experimental results. Conclusions: Our results have the potential to be a stepping stone to develop pre-operative surgical planning to estimate an optimal needle insertion path for MR image-guided microwave coagulation therapy and for analyzing large deformation and fracture in biological tissues. © 2014 Elsevier Ltd.

We present a study in human-centered automation that has potential to reduce patient side effects from high dose rate brachytherapy (HDR-BT). To efficiently deliver radiation to the prostate while minimizing trauma to sensitive structures such as the penile bulb, we modified the Acubot-RND 7-axis robot to guide insertion of diamond-tip needles into desired skew-line geometric arrangements. We extend and integrate two algorithms: Needle Planning with Integer Programming (NPIP) and Inverse Planning with Integer Programming (IPIP) to compute skew-line needle and dose plans. We performed three physical experiments with anatomically correct phantom models to study performance: two with the robot and one control experiment with an expert human physician (coauthor Hsu) without the robot. All were able to achieve needle arrangements that meet the RTOG-0321 clinical dose objectives with zero trauma to the penile bulb. We analyze systematic and random errors in needle placement; total RMS error for the robot system operating without feedback ranged from 2.6 to 4.3 mm, which is comparable to the RMS error of 2.7 mm obtained in an earlier study for PPI-BT treatment using a robot with 3D ultrasound feedback. © 2004-2012 IEEE.

We present a study in human-centered automation that has potential to reduce patient side effects from high dose rate brachytherapy (HDR-BT). To efficiently deliver radiation to the prostate while minimizing trauma to sensitive structures such as the penile bulb, we modified the Acubot-RND 7-axis robot to guide insertion of diamond-tip needles into desired skew-line geometric arrangements. We extend and integrate two algorithms: Needle Planning with Integer Programming (NPIP) and Inverse Planning with Integer Programming (IPIP) to compute skew-line needle and dose plans. We performed three physical experiments with anatomically correct phantom models to study performance: two with the robot and one control experiment with an expert human physician (coauthor Hsu) without the robot. All were able to achieve needle arrangements that meet the RTOG-0321 clinical dose objectives with zero trauma to the penile bulb. We analyze systematic and random errors in needle placement; total RMS error for the robot system operating without feedback ranged from 2.6 to 4.3 mm, which is comparable to the RMS error of 2.7 mm obtained in an earlier study for PPI-BT treatment using a robot with 3D ultrasound feedback. © 2004-2012 IEEE.

Accurate positioning of the needle tip during insertion is essential to ensure a maximum effect of the treatment. Target error is a problem and a lot research fields aim to improve needle insertions. The possibility to measure cutting force and stiffness force separately from friction forces supports the development of new types of needles, needle insertion simulators and needle insertion robots for use in a clinical environment. The goal of this work is to create a needle that can measure these forces. The design is used in an insertion experiment, to determine if this force information can be used to determine tissue properties and differentiate between tissue layers. A new trocar needle design is presented for measuring forces in the tip of the cutting stylet, only measuring the cutting forces and stiffness forces and excluding the friction forces on the shaft. Through the centre of the stylet of a 20 cm 18 G trocar needle runs an optic fibre with a fibre Bragg grating close to the tip, that will function as an optical strain sensor. The interrogator measures the Bragg wavelength shift caused by a change in strain. The grating is embedded in a PVC jacket to increase the strain in the grating. Calibration was performed in a universal test machine to determine the force - wavelength relationship in a range of 0 - 10 N at different constant temperatures. The calibrated prototype was used in insertion experiments in a phantom model and in an ex vivo tissue model. The total axial force is compared to the prototype output. The calibration revealed a linear force - wavelength relationship where the slope coefficient increases with increasing temperature. The calibration showed an average error of 0.1069 N. In the insertion experiment the output of the prototype has a good correlation with the total axial force. Puncture events are clearly identified in both samples. In the phantom tissue it is seen that the different layers can be differentiated by the gradual change in, MIMS, BioMechanical Engineering, Mechanical, Maritime and Materials Engineering

Accurate positioning of the needle tip during insertion is essential to ensure a maximum effect of the treatment. Target error is a problem and a lot research fields aim to improve needle insertions. The possibility to measure cutting force and stiffness force separately from friction forces supports the development of new types of needles, needle insertion simulators and needle insertion robots for use in a clinical environment. The goal of this work is to create a needle that can measure these forces. The design is used in an insertion experiment, to determine if this force information can be used to determine tissue properties and differentiate between tissue layers. A new trocar needle design is presented for measuring forces in the tip of the cutting stylet, only measuring the cutting forces and stiffness forces and excluding the friction forces on the shaft. Through the centre of the stylet of a 20 cm 18 G trocar needle runs an optic fibre with a fibre Bragg grating close to the tip, that will function as an optical strain sensor. The interrogator measures the Bragg wavelength shift caused by a change in strain. The grating is embedded in a PVC jacket to increase the strain in the grating. Calibration was performed in a universal test machine to determine the force - wavelength relationship in a range of 0 - 10 N at different constant temperatures. The calibrated prototype was used in insertion experiments in a phantom model and in an ex vivo tissue model. The total axial force is compared to the prototype output. The calibration revealed a linear force - wavelength relationship where the slope coefficient increases with increasing temperature. The calibration showed an average error of 0.1069 N. In the insertion experiment the output of the prototype has a good correlation with the total axial force. Puncture events are clearly identified in both samples. In the phantom tissue it is seen that the different layers can be differentiated by the gradual change in, MIMS, BioMechanical Engineering, Mechanical, Maritime and Materials Engineering

Epidural anaesthesia is a pain relief technique commonly performed on patients in labor. It requires insertion of a needle into patients back into the epidural space of the spine and inject anaesthetic. It is a blind procedure and anaesthesiologists rely only on the forces felt during needle insertion to determine the position of the needle tip. It is a complex procedure that requires training. However, in a majority of hospitals the residents are trained on patiets. In this thesis development and validation of a new epidural needle insertion simulator with haptic feedback is discussed. . The simulator has 1DOF for needle insertion and 1DOF for needle orientation. The simulator uses a cable-pulley mechanism to transmit forces to the needle. The simulator provides active force-feedback by means of a motor in the needle insertion direction and passive force-feedback by means of a brake in the needle orientation direction. The simulator simulates needle-tissue and needle-bone interaction forces. It also incorporates simulation of different virtual patients, which can be selected from the graphical user interface. The real-time position of the needle can be seen in the graphical user interface. The simulator is validated through experiments by expert anaesthesiologists and novices. The simulator is validated for face and constuct validity. The results were promising showing high acceptance rate with addition of some features. Moreover, difference in performance between experts and novices was found and thus evaluating similarity to a real scenario., BioMechanical Engineering, Mechanical, Maritime and Materials Engineering

Epidural anaesthesia is a pain relief technique commonly performed on patients in labor. It requires insertion of a needle into patients back into the epidural space of the spine and inject anaesthetic. It is a blind procedure and anaesthesiologists rely only on the forces felt during needle insertion to determine the position of the needle tip. It is a complex procedure that requires training. However, in a majority of hospitals the residents are trained on patiets. In this thesis development and validation of a new epidural needle insertion simulator with haptic feedback is discussed. . The simulator has 1DOF for needle insertion and 1DOF for needle orientation. The simulator uses a cable-pulley mechanism to transmit forces to the needle. The simulator provides active force-feedback by means of a motor in the needle insertion direction and passive force-feedback by means of a brake in the needle orientation direction. The simulator simulates needle-tissue and needle-bone interaction forces. It also incorporates simulation of different virtual patients, which can be selected from the graphical user interface. The real-time position of the needle can be seen in the graphical user interface. The simulator is validated through experiments by expert anaesthesiologists and novices. The simulator is validated for face and constuct validity. The results were promising showing high acceptance rate with addition of some features. Moreover, difference in performance between experts and novices was found and thus evaluating similarity to a real scenario., BioMechanical Engineering, Mechanical, Maritime and Materials Engineering

We present algorithms for simulating and visualizing the insertion and steering of needles throughdeformable tissues for surgical training and planning. Needle insertion is an essential component ofmany clinical procedures such as biopsies, injections, neurosurgery, and brachytherapy cancer treatment.The success of these procedures depends on accurate guidance of the needle tip to a clinicaltarget while avoiding vital tissues. Needle insertion deforms body tissues, making accurate placementdifficult. Our interactive needle insertion simulator models the coupling between a flexibleneedle and deformable tissue. We introduce (1) a novel algorithm for local remeshing that quicklyenforces the conformity of a tetrahedral mesh to a curvilinear needle path, enabling accurate computationof contact forces, (2) an efficient method for coupling a 3D finite element simulation with a1D inextensible rod with stick-slip friction, and (3) optimizations that reduce the computation timefor physically based simulations. We can realistically and interactively simulate needle insertioninto a prostate mesh of 13,375 tetrahedra and 2,763 vertices at a 25 Hz frame rate on an 8-core 3.0GHz Intel Xeon PC. The simulation models prostate brachytherapy with needles of varying stiffness,steering needles around obstacles, and supports motion planning for robotic needle insertion.We evaluate the accuracy of the simulation by comparing against real-world experiments in whichflexible, steerable needles were inserted into gel tissue phantoms.

We present algorithms for simulating and visualizing the insertion and steering of needles throughdeformable tissues for surgical training and planning. Needle insertion is an essential component ofmany clinical procedures such as biopsies, injections, neurosurgery, and brachytherapy cancer treatment.The success of these procedures depends on accurate guidance of the needle tip to a clinicaltarget while avoiding vital tissues. Needle insertion deforms body tissues, making accurate placementdifficult. Our interactive needle insertion simulator models the coupling between a flexibleneedle and deformable tissue. We introduce (1) a novel algorithm for local remeshing that quicklyenforces the conformity of a tetrahedral mesh to a curvilinear needle path, enabling accurate computationof contact forces, (2) an efficient method for coupling a 3D finite element simulation with a1D inextensible rod with stick-slip friction, and (3) optimizations that reduce the computation timefor physically based simulations. We can realistically and interactively simulate needle insertioninto a prostate mesh of 13,375 tetrahedra and 2,763 vertices at a 25 Hz frame rate on an 8-core 3.0GHz Intel Xeon PC. The simulation models prostate brachytherapy with needles of varying stiffness,steering needles around obstacles, and supports motion planning for robotic needle insertion.We evaluate the accuracy of the simulation by comparing against real-world experiments in whichflexible, steerable needles were inserted into gel tissue phantoms.

Lead perforation is a rare but serious complication of pacemaker implantations, and in the present study the associated tissue failure was investigated by means of in-vitro penetration of porcine and bovine ventricular tissue. Rectangular patches from the right ventricular free wall and the interventricular were separated, bi-axially stretched and immersed in physiological salt solution at 37 C before load displacement curves of m total 891 penetrations were recorded. To this end flat-bottomed cylindrical punches of different diameters were used, and following mechanical testing the penetration were histological analyzed using light and electron microscopes. Penetration pressure, i.e. penetration force divided by punch cross-sectional area decreased slightly from 2.27(SD 0.66) to 1.76 (SD 0.46) N mm(2) for punches of 1.32 to 2.30 mm in diameter, respectively. Deep penetration formed cleavages aligned with the local fiber orientation of the tissue, and hence, a mode-I crack developed, where the crack faces were wedged open by the advancing punch. The performed study derived novel failure data from ventricular tissue due to deep penetration and uncovered associated failure mechanisms. This provides information to derive mechanical failure models, which are essential to enrich our current understanding of failure of soft biological tissues and to guide medical device development., QC 20100525

Yamaguchi S., Tsutsui K., Satake K., et al. Dynamic analysis of a needle insertion for soft materials: Arbitrary Lagrangian-Eulerian-based three-dimensional finite element analysis. Computers in Biology and Medicine 53, 42 (2014); https://doi.org/10.1016/j.compbiomed.2014.07.012., Background: Our goal was to develop a three-dimensional finite element model that enables dynamic analysis of needle insertion for soft materials. To demonstrate large deformation and fracture, we used the arbitrary Lagrangian-Eulerian (ALE) method for fluid analysis. We performed ALE-based finite element analysis for 3% agar gel and three types of copper needle with bevel tips. Methods: To evaluate simulation results, we compared the needle deflection and insertion force with corresponding experimental results acquired with a uniaxial manipulator. We studied the shear stress distribution of agar gel on various time scales. Results: For 30°, 45°, and 60°, differences in deflections of each needle between both sets of results were 2.424, 2.981, and 3.737. mm, respectively. For the insertion force, there was no significant difference for mismatching area error (p<0.05) between simulation and experimental results. Conclusions: Our results have the potential to be a stepping stone to develop pre-operative surgical planning to estimate an optimal needle insertion path for MR image-guided microwave coagulation therapy and for analyzing large deformation and fracture in biological tissues. © 2014 Elsevier Ltd.

Yamaguchi S., Tsutsui K., Satake K., et al. Dynamic analysis of a needle insertion for soft materials: Arbitrary Lagrangian-Eulerian-based three-dimensional finite element analysis. Computers in Biology and Medicine 53, 42 (2014); https://doi.org/10.1016/j.compbiomed.2014.07.012., Background: Our goal was to develop a three-dimensional finite element model that enables dynamic analysis of needle insertion for soft materials. To demonstrate large deformation and fracture, we used the arbitrary Lagrangian-Eulerian (ALE) method for fluid analysis. We performed ALE-based finite element analysis for 3% agar gel and three types of copper needle with bevel tips. Methods: To evaluate simulation results, we compared the needle deflection and insertion force with corresponding experimental results acquired with a uniaxial manipulator. We studied the shear stress distribution of agar gel on various time scales. Results: For 30°, 45°, and 60°, differences in deflections of each needle between both sets of results were 2.424, 2.981, and 3.737. mm, respectively. For the insertion force, there was no significant difference for mismatching area error (p<0.05) between simulation and experimental results. Conclusions: Our results have the potential to be a stepping stone to develop pre-operative surgical planning to estimate an optimal needle insertion path for MR image-guided microwave coagulation therapy and for analyzing large deformation and fracture in biological tissues. © 2014 Elsevier Ltd.