Intra-operative tumour localisation in robot-assisted minimally invasive surgery: A review

Bioinspired adaptable multiplanar mechano-vibrotactile haptic system

Several gaps persist in haptic device development due to the multifaceted nature of the sense of touch. Existing gaps include challenges enhancing touch feedback fidelity, providing diverse haptic sensations, and ensuring wearability for delivering tactile stimuli to the fingertips. Here, we introduce the Bioinspired Adaptable Multiplanar Haptic system, offering mechanotactile/steady and vibrotactile pulse stimuli with adjustable intensity (up to 298.1 mN) and frequencies (up to 130 Hz). This system can deliver simultaneous stimuli across multiple fingertip areas. The paper includes a full characterisation of our system. As the device can play an important role in further understanding human touch, we performed human stimuli sensitivity and differentiation experiments to evaluate the capability of delivering mechano-vibrotactile, variable intensity, simultaneous, multiplanar and operator agnostic stimuli. Our system promises to accelerate the development of touch perception devices, providing painless, operator-independent data crucial for researching and diagnosing touch-related disorders.

Design and comparison of computationally efficient uniaxial stress-strain models of the lung parenchyma for real-time applications

Real-time clinical applications such as robotic lung surgery, tumor localization, atelectasis diagnosis, tumor motion prediction for radiation therapy of lung cancer, or surgery training are in need of biomechanical models of lungs, not necessarily highly accurate, but with good computational properties. These properties can include one or several of the following: low computation time, low memory resource requirement, a low number of parameters, and ease of parameter identification in real-time. Among the numerous existing models of lung parenchyma, some may be well suited for real-time applications; however, they should be extensively assessed against both accuracy and computational efficiency criteria to make an informed choice depending on the requirements of the application. After demonstrating how to derive a real-time compliant force-indentation model from a unixial stress-strain model with rational expression, the core purpose of this paper is to propose such an evaluation of selected models in fitting human lung parenchyma experimental and synthetic data of uniaxial tension. Furthermore, new uniaxial stress-strain models are developed based on an empirical observation of the volumetric behavior of the lungs along with an emphasis on computational performance. These new proposed models are competitive with existing one in terms of computational efficiency and compliance with experimental and synthetic data. One of them reduces the prediction error by 2 compared to other investigated models while maintaining an excellent adjusted coefficient of determination between 0.999 and 1 across various datasets. It exhibits excellent real-time capabilities with an explicit rational expression, only 3 parameters and linear numerator and denominator in the parameters. It is computed with only 20 floating point operations (flops) while another proposed model even requires as few as 2 flops.

A Minimally Invasive Robotic Tissue Palpation Device

OBJECTIVE

Robot-assisted minimally invasive surgery remains limited by the absence of haptic feedback, which surgeons routinely rely on to assess tissue stiffness. This limitation hinders surgeons' ability to identify and treat abnormal tissues, such as tumors, during robotic surgery.

METHODS

To address this challenge, we developed a robotic tissue palpation device capable of rapidly and non-invasively quantifying the stiffness of soft tissues, allowing surgeons to make objective and data-driven decisions during minimally invasive procedures. We evaluated the effectiveness of our device by measuring the stiffness of phantoms as well as lung, heart, liver, and skin tissues obtained from both rats and swine.

RESULTS

Results demonstrated that our device can accurately determine tissue stiffness and identify tumor mimics. Specifically, in swine lung, we determined elastic modulus (E) values of 9.1 ± 2.3, 16.8 ± 1.8, and 26.0 ± 3.6 kPa under different internal pressure of the lungs (PIP) of 2, 25, and 45 cmH2O, respectively. Using our device, we successfully located a 2-cm tumor mimic embedded at a depth of 5 mm in the lung subpleural region. Additionally, we measured E values of 33.0 ± 5.4, 19.2 ± 2.2, 33.5 ± 8.2, and 22.6 ± 6.0 kPa for swine heart, liver, abdominal skin, and muscle, respectively, which closely matched existing literature data.

CONCLUSION/SIGNIFICANCE

Results suggest that our robotic palpation device can be utilized during surgery, either as a stand-alone or additional tool integrated into existing robotic surgical systems, to enhance treatment outcomes by enabling accurate intraoperative identification of abnormal tissue.

A roller scanning type prostate palpation sensor system using a cantilever beam type force measurement

Palpation has been used for centuries in medicine as a screening and diagnosis modality for a number of pathological conditions. However, this technique is subjective since palpation sensitivity depends on the skill and experience of a medical examiner. An objective approach to acquire quantitative tactile information is needed. A roller scanning type palpation sensor system consisting of an x-axis linear slider and a palpation probe for detecting lumps in a soft object such as the prostate tissue is proposed and fabricated in this study. By translating the slider and changing the palpation angle of the probe, a chrome steel ball which was the contact component indented and scanned the surface of soft silicone phantoms embedded with hard lumps. Lumps were detected by measuring reaction force waveform fluctuations. Fundamental characteristics of the proposed sensor system were validated by comparison with the ground truth load cell output and showed a strong linear correlation with r²=0.9985. On silicone samples with hard lumps, the system was able to detect lumps of various sizes embedded at the depth of 5mm. From the results, the proposed sensor system holds potential for tissue characterization.

Development of a tendon driven robotic probe for prostate palpation

Palpation is a clinical diagnosis method utilized by physicians to acquire valuable information about the pathological condition of an organ using the sense of touch. This method, however, is subjective. The accuracy depends on the physician's experience and skill. Therefore, to make palpation objective and minimize variability in prostate cancer diagnosis among physicians, an automated palpation system is required. This paper describes the design and experimental evaluation of a 2 Degrees of Freedom (2DoF) tendon driven robotic palpation probe. The probe's palpation motion is controlled by actuating driving tendons using a cable-differential pulley transmission system and a return spring. A kinematic model of the robotic probe was derived. Furthermore, a tendon path length model was geometrically determined, and an optimization method for guide arc center placement to minimize change in tendon length was presented. Preliminary experimental and theoretical results were compared to determine the positioning accuracy. The difference between theoretical pitch angles [0°,80°] and measured values for the yaw angle range of [0°, 40°] was found to be in the range of 0.03° ~ 5.06°.Clinical Relevance- Diagnosis based on manual palpation is often subjective and palpation sensitivity depends on the physician's level of experience and skill. Therefore, an objective method for acquiring tactile information is relevant. Robotic palpation system provides objective and quantitative information for better understanding of the pathological and physiological changes in the tissue using mechanical properties as biomarkers.

Haptic Intracorporeal Palpation Using a Cable-Driven Parallel Robot: A User Study

OBJECTIVE

Intraoperative palpation is a surgical gesture jeopardized by the lack of haptic feedback which affects robotic minimally invasive surgery. Restoring the force reflection in teleoperated systems may improve both surgeons' performance and procedures' outcome.

METHODS

A force-based sensing approach was developed, based on a cable-driven parallel manipulator with anticipated seamless and low-cost integration capabilities in teleoperated robotic surgery. No force sensor on the end-effector is used, but tissue probing forces are estimated from measured cable tensions. A user study involving surgical trainees (n = 22) was conducted to experimentally evaluate the platform in two palpation-based test-cases on silicone phantoms. Two modalities were compared: visual feedback alone and both visual + haptic feedbacks available at the master site.

RESULTS

Surgical trainees' preference for the modality providing both visual and haptic feedback is corroborated by both quantitative and qualitative metrics. Hard nodules detection sensitivity improves (94.35 ± 9.1% vs 76.09 ± 19.15% for visual feedback alone), while also exerting smaller forces (4.13 ± 1.02 N vs 4.82 ± 0.81 N for visual feedback alone) on the phantom tissues. At the same time, the subjective perceived workload decreases.

CONCLUSION

Tissue-probe contact forces are estimated in a low cost and unique way, without the need of force sensors on the end-effector. Haptics demonstrated an improvement in the tumor detection rate, a reduction of the probing forces, and a decrease in the perceived workload for the trainees.

SIGNIFICANCE

Relevant benefits are demonstrated from the usage of combined cable-driven parallel manipulators and haptics during robotic minimally invasive procedures. The translation of robotic intraoperative palpation to clinical practice could improve the detection and dissection of cancer nodules.

Reaction Force Mapping by 3-Axis Tactile Sensing With Arbitrary Angles for Tissue Hard-Inclusion Localization

Although robot-assisted diagnosis and minimally invasive surgery (MIS) brings distinct benefits, deficient multi-dimensional force feedback remains a noteworthy limitation and challenge in MIS. Aiming for a comprehensive high-fidelity perception of tissue-instrument interactions, we present a Fiber Bragg Grating (FBG)-based 3-axis tactile sensing for surface reaction force mapping, identification and localization of tissue hard-inclusion. The tactile sensing probe consists of five optical fibers inscribed with FBGs and a force-sensitive 3D printed deformable body. All fibers are suspended inside the deformable body in a parallel manner, leading to the direct compression or tension of each FBG. Such configuration can effectively avoid the chirping failure of FBG compared with the pasting FBG-based sensors. A linearized difference model is proposed to calibrate the 3-axis force detection and enhance the resistance to nonlinear interferences. Hard-inclusion identification experiments with varied hard-inclusion sizes and depths have been implemented through discrete palpation and dragging palpation modes. Results indicate that the probe can effectively identify the presence and location of these small hard-inclusions from the force mapping. Furthermore, lengthy vessels embedded in the phantom can be accurately identified through dragging palpation with an arbitrary contact angle. Another novelty of the probe is the reconstruction of the surface profile of a non-planar tissue, which further allows hard-inclusion identification and 3D localization. Ex-vivo tissue palpation on a porcine kidney further validates the effectiveness and feasibility of the probe to map surface reaction forces and localize the hard-inclusions intraoperatively.

A review on recent advances in soft surgical robots for endoscopic applications

BACKGROUND

Soft materials, with their compliant properties, enable conformity and safe interaction with human body. With the advance in actuation and sensing of soft materials, new paradigm in robotics called "soft robotics" emerges. Soft robotics has become a new approach in designing medical devices such as wearable robotic gloves and exoskeleton. However, application of soft robotics in surgical instrument inside human body is still in its infancy.

AIMS

In this paper, current application and design of soft robots specifically applied for endoscopy are reviewed.

MATERIALS & METHODS

Different aspects in the implementation of soft robotics in endoscope design were reviewed. The key studies about MIS and NOTES were reviewed to establish the clinical background and extract the limitations of current endoscopic device in the last decade.

RESULTS AND DISCUSSION

In this review study, the implementation of soft robotics concepts in endoscopic application, with highlights on different features of several soft endoscopes, were evaluated. The progress in different aspects of soft robotics endoscope, current state, and future perspectives were also discussed.

CONCLUSION

Based on the survey on the structural specification, actuation, sensing, and stiffening the future soft surgical endoscopes are recommended to fulfil the following specifications: safe especially from pressure leakage, fully biocompatible materials, MR-compatible, capable for large bending in at least two antagonistic directions, modularity, adjustable stiffness.

A resonant tactile stiffness sensor for lump localization in robot-assisted minimally invasive surgery

A miniature resonant tactile sensor for tissue stiffness detection in robot-assisted minimally invasive surgery is proposed in this article. The proposed tactile sensor can detect tissue stiffness based on the principle of the resonant frequency shift when it contacts with tissue of different stiffness. A PZT (lead zirconate titanate) bimorph works simultaneously as the actuator and the sensing element, which is helpful for simplifying the structure. The resonant frequency shift can be deduced by measuring the electrical impedance of the PZT bimorph, since there will be an abrupt change of the impedance when resonance occurs. A unique structure of an Archimedean spiral metal sheet is introduced to restrict the outer size of the sensor within 10 mm and to keep the resonant frequency low. A theoretical model is established. Finite element method analyses are carried out to validate the working principle and it meets the theoretical model quite well. Several silicone samples are tested with the sensor and the results show that the proposed sensor is capable of measuring tissue stiffness within the range of 0-2 MPa, detecting and locating lumps inside tissue.

A Pneumatic Tactile Ring for Instantaneous Sensory Feedback in Laparoscopic Tumor Localization

We aim to achieve intraoperative localization of an early-stage gastric tumor that cannot be visually detected during laparoscopic surgery. In this study, we developed and evaluated a pneumatic tactile ring, which is a clinically applicable tactile device to provide instantaneous feedback from a tactile sensor directly manipulated by a surgeon. It was designed to be worn on the finger of the manipulating hand and to present pressure to the finger pad. It is lightweight, cost-effective, disposable, and sterilizable. We also developed a compact pneumatic drive unit to control the pressure and investigated its fundamental performance. The bandwidth of the pressure control was at least 1.3 Hz with a controllable range of up to 79.7 kPa. Moreover, a psychophysical experiment was performed to obtain the Weber ratio of the pressure and evaluate the effectiveness of the instantaneous tactile feedback of the sensor output through the tactile ring. The Weber ratio was 0.40 at the reference pressure of 22.7 kPa. The provided tactile feedback significantly reduced the absolute localization error and increased participants' confidence in their answers. It was shown that the tactile feedback through the ring is effective in laparoscopic tumor localization.

Prevalence of haptic feedback in robot-mediated surgery: a systematic review of literature

With the successful uptake and inclusion of robotic systems in minimally invasive surgery and with the increasing application of robotic surgery (RS) in numerous surgical specialities worldwide, there is now a need to develop and enhance the technology further. One such improvement is the implementation and amalgamation of haptic feedback technology into RS which will permit the operating surgeon on the console to receive haptic information on the type of tissue being operated on. The main advantage of using this is to allow the operating surgeon to feel and control the amount of force applied to different tissues during surgery thus minimising the risk of tissue damage due to both the direct and indirect effects of excessive tissue force or tension being applied during RS. We performed a two-rater systematic review to identify the latest developments and potential avenues of improving technology in the application and implementation of haptic feedback technology to the operating surgeon on the console during RS. This review provides a summary of technological enhancements in RS, considering different stages of work, from proof of concept to cadaver tissue testing, surgery in animals, and finally real implementation in surgical practice. We identify that at the time of this review, while there is a unanimous agreement regarding need for haptic and tactile feedback, there are no solutions or products available that address this need. There is a scope and need for new developments in haptic augmentation for robot-mediated surgery with the aim of improving patient care and robotic surgical technology further.

Endoscopic add-on stiffness probe for real-time soft surface characterisation in MIS

This paper explores a novel stiffness sensor which is mounted on the tip of a laparoscopic camera. The proposed device is able to compute stiffness when interacting with soft surfaces. The sensor can be used in Minimally Invasive Surgery, for instance, to localise tumor tissue which commonly has a higher stiffness when compared to healthy tissue. The purely mechanical sensor structure utilizes the functionality of an endoscopic camera to the maximum by visually analyzing the behavior of trackers within the field of view. Two pairs of spheres (used as easily identifiable features in the camera images) are connected to two springs with known but different spring constants. Four individual indenters attached to the spheres are used to palpate the surface. During palpation, the spheres move linearly towards the objective lens (i.e. the distance between lens and spheres is changing) resulting in variations of their diameters in the camera images. Relating the measured diameters to the different spring constants, a developed mathematical model is able to determine the surface stiffness in real-time. Tests were performed using a surgical endoscope to palpate silicon phantoms presenting different stiffness. Results show that the accuracy of the sensing system developed increases with the softness of the examined tissue.