微创手术过程中的手术烟雾仿真

手术烟雾是微创手术过程中对患者和医师健康产生危害的重要来源,也是手术风险控制中的重要环节。现阶段对这一复杂流体现象的仿真在精确性和可交互性等方面都有一定局限。通过改进的涡粒子方法将传统的流体模型与基于无网格的算法相结合,实现了面向微创消融术的手术烟雾仿真。该方法将传统模型在计算烟雾流体时因数值耗散而丢失的流体细节以涡量约束力的形式重新耦合进流体方程中,实现了对包括小尺度涡在内的流体细节的还原。同时通过GPU并行加速的方法和基于患者医学图片重建的三维模型实现了可交互式的仿真。仿真结果展现了较高的真实性和流体细节,实现了良好的计算优化及程序拓展性,为未来应用中的手术规划及训练奠定了基础。     

A novel tactile softness display for minimally invasive surgery

The use of Minimally Invasive Surgery (MIS) in various types of surgical procedures has increased significantly in recent years. However, its scope is limited due mainly to the fact that this procedure does not currently provide tactile feedback without which the surgeon can neither feel nor palpate tissue. In this paper, we describe a new tactile display that reproduces these missing constituent properties of the tissue directly to the surgeon. The softness of different objects is regenerated based on the mechanical properties of those objects and fingertip pulp. The force–displacement non-linear behavior of several different materials is simulated using force feedback and a Proportional-Integral-Derivative (PID) controller for the linear actuator. Experimental tests show that the proposed tactile display can closely regenerate the feeling of softness for different objects by rendering the force–displacement curve to the surgeon’s hand.     

Self-calibrating 3D-ultrasound-based bone registration for minimally invasive orthopedic surgery

Intraoperative freehand three-dimensional (3-D) ultrasound (3D-US) has been proposed as a noninvasive method for registering bones to a preoperative computed tomography image or computer-generated bone model during computer-aided orthopedic surgery (CAOS). In this technique, an US probe is tracked by a 3-D position sensor and acts as a percutaneous device for localizing the bone surface. However, variations in the acoustic properties of soft tissue, such as the average speed of sound, can introduce significant errors in the bone depth estimated from US images, which limits registration accuracy. We describe a new self-calibrating approach to US-based bone registration that addresses this problem, and demonstrate its application within a standard registration scheme. Using realistic US image data acquired from 6 femurs and 3 pelves of intact human cadavers, and accurate Gold Standard registration transformations calculated using bone-implanted fiducial markers, we show that self-calibrating registration is significantly more accurate than a standard method, yielding an average root mean squared target registration error of 1.6 mm. We conclude that self-calibrating registration results in significant improvements in registration accuracy for CAOS applications over conventional approaches where calibration parameters of the 3D-US system remain fixed to values determined using a preoperative phantom-based calibration.     

A manually operated, advance off-stylet insertion tool for minimally invasive cochlear implantation surgery

The current technique for cochlear implantation (CI) surgery requires a mastoidectomy to gain access to the cochlea for electrode array insertion. It has been shown that microstereotactic frames can enable an image-guided, minimally invasive approach to CI surgery called percutaneous cochlear implantation (PCI) that uses a single drill hole for electrode array insertion, avoiding a more invasive mastoidectomy. Current clinical methods for electrode array insertion are not compatible with PCI surgery because they require a mastoidectomy to access the cochlea; thus, we have developed a manually operated electrode array insertion tool that can be deployed through a PCI drill hole. The tool can be adjusted using a preoperative CT scan for accurate execution of the advance off-stylet (AOS) insertion technique and requires less skill to operate than is currently required to implant electrode arrays. We performed three cadaver insertion experiments using the AOS technique and determined that all insertions were successful using CT and microdissection.     

Generalized approach for modeling minimally invasive surgery as a stochastic process using a discrete Markov model

Minimally invasive surgery (MIS) involves a multidimensional series of tasks requiring a synthesis between visual information and the kinematics and dynamics of the surgical tools. Analysis of these sources of information is a key step in defining objective criteria for characterizing surgical performance. The Blue DRAGON is a new system for acquiring the kinematics and the dynamics of two endoscopic tools synchronized with the endoscopic view of the surgical scene. Modeling the process of MIS using a finite state model [Markov model (MM)] reveals the internal structure of the surgical task and is utilized as one of the key steps in objectively assessing surgical performance. The experimental protocol includes tying an intracorporeal knot in a MIS setup performed on an animal model (pig) by 30 surgeons at different levels of training including expert surgeons. An objective learning curve was defined based on measuring quantitative statistical distance (similarity) between MM of experts and MM of residents at different levels of training. The objective learning curve was similar to that of the subjective performance analysis. The MM proved to be a powerful and compact mathematical model for decomposing a complex task such as laparoscopic suturing. Systems like surgical robots or virtual reality simulators in which the kinematics and the dynamics of the surgical tool are inherently measured may benefit from incorporation of the proposed methodology.     

Design of minimally invasive all-pole analog lowpass filters

In this paper, a new design technique for designing higher order minimally invasive lowpass filters is proposed. The proposed fully differential filter has been simulated in TSMC 130 nm technology for third and fourth orders. When compared with the conventional filter implementations such as a Tow-Thomas architecture, the proposed third order solution achieves a total in-band input-referred integrated noise of \(44.09\,\upmu V\) compared to \(78.83\,\upmu V\), achieved by a Tow-Thomas implementation. The proposed solution offers higher tolerance to blockers along with lesser number of active devices required. Though, the total capacitance used is increased from 23.82 pF to 89.82 pF, from third order Tow-Thomas filter to its minimally invasive filter counterpart, the power consumption reduces by \(77\,\%\) from third order Tow-Thomas to the third order minimally invasive filter.     

Biomedical microsystems for minimally invasive diagnosis and treatment

Great significant progress has been made in the development of biomedical microdevices in recent years, and these devices are now playing an important role in diagnosis and therapy. This paper presents a review of applications of microelectromechanical systems (MEMS) devices for in vivo diagnosis and therapy, and endoscopic- and catheter-based interventions. MEMS technology has enabled the further development of advanced biomedical microdevices for use in the human body by integration of sensors, actuators, and electronics into small medical devices for use in the body. In this paper, we discuss three categories of such devices: navigation systems, sensors and actuators for catheters and endoscopes, and other minimally invasive techniques. A brief introduction to principles, device structures, packaging, and related issues is presented.     

Applications of MEMS in surgery

In the past few decades, microelectromechanical systems (MEMS) have found themselves being adopted into a wide variety of fields and disciplines. Recently there has been an increased interest in the use of MEMS for surgical applications. MEMS technology has the potential to not only improve the functionality of existing surgical devices, but also add new capabilities, which allow surgeons to develop new techniques and perform entirely new procedures. MEMS can improve surgical outcomes, lower risk, and help control costs by providing the surgeon with real-time feedback on the operation. This paper discusses the challenges MEMS face in the medical device market along with current applications and future directions for the technology.     

Photonic crystal fiber sensors for minimally invasive surgical devices

The measurement of interaction forces in minimally invasive surgical devices, sensorized with photonic crystal fiber (PCF) sensors, is presented in this paper. Two types of PCF sensors are used: a tapered PCF interferometer and a microhole-collapsed PCF interferometer for the detection of interaction forces generated in surgical devices without the influence of ambient temperature variation. The demonstration devices used for force characterization are a laparoscopic scissor and a standard surgical scissor blade. The force sensitivity of each sensorized blade is examined and compared with fiber Bragg grating (FBG)-sensorized blades. Results show that the PCF-sensorized surgical blades outperform the blades fitted with the FBG sensors during static load measurement.     

Technology improvements for image-guided and minimally invasive spine procedures

This paper reports on technology developments aimed at improving the state of the art for image-guided minimally invasive spine procedures. Back pain is a major health problem with serious economic consequences. Minimally invasive procedures to treat back pain are rapidly growing in popularity due to improvements in technique and the substantially reduced trauma to the patient versus open spinal surgery. Image guidance is an enabling technology for minimally invasive procedures, but technical problems remain that may limit the wider applicability of these techniques. The paper begins with a discussion of low back pain and the potential shortcomings of open back surgery. The advantages of minimally invasive procedures are enumerated, followed by a list of technical problems that must be overcome to enable the more widespread dissemination of these techniques. The technical problems include improved intraoperative imaging, fusion of images from multiple modalities, the visualization of oblique paths, percutaneous spine tracking, mechanical instrument guidance, and software architectures for technology integration. Technical developments to address some of these problems are discussed next. The discussion includes intraoperative computerized tomography (CT) imaging, magnetic resonance imaging (MRI)/CT image registration, three-dimensional (3-D) visualization, optical localization, and robotics for percutaneous instrument placement. Finally, the paper concludes by presenting several representative clinical applications: biopsy, vertebroplasty, nerve and facet blocks, and shunt placement. The program presented here is a first step to developing the physician-assist systems of the future, which will incorporate visualization, tracking, and robotics to enable the precision placement and manipulation of instruments with minimal trauma to the patient.     

Fiber-coupled in-line heterodyne optical interferometer for minimally invasive sensing

In this paper, the first fiber-coupled no-moving-parts scanning heterodyne interferometer design using a single acoustooptic device (AOD) is reported. The design features a high-stability inline reflective architecture with free-space-scanned minimally invasive sensing via a multizone reflective sensor chip. The common path fiber interconnection allows robust remoting of the compact sensing front end. A proof-of-concept sensing experiment measuring voltage-dependent birefringence is successfully conducted using a voltage-controlled nematic liquid crystal (NLC) sensor chip. The system features a 4.69-dB optical loss, a 200-MHz output frequency, and a 1550-nm eye-safe operation wavelength. Applications for the system include any fiber-remoted sensing using the proposed free-space minimally invasive interrogating optical beams.     

早期经鼻气管插管对高血压脑出血患者微创治疗后肺部感染的影响

目的研究早期经鼻气管插管对高血压脑出血患者微创治疗术后肺部感染发生率、ICU治疗时间的影响。方法选取58例2007年9月-2009年5月间于我院急诊科就诊并拟行微创治疗的高血压幕上型脑出血患者。根据GCS评分分层后进行随机分组,处理组于就诊时予以早期经鼻气管插管经人工鼻吸氧,对照组予以鼻导管或面罩吸氧,观察术后72h肺炎并发症发生率及ICU治疗时间,研究数据选取Fisher确切概率法及成组t检验方法进行统计分析。结果不管在GCS评分13～15分或6～12分的高血压脑出血患者中,早期插管组与对照组在术后肺炎发生率方面的差异无统计学意义(GCS13～15:21.4%vs35.7%,P=0.6776;GCS6～12:60%vs80%,P=0.2678),但在ICU治疗时间方面早期插管组较对照组明显缩短,两者间差异具有显著统计学意义(GCS13～15:4.9dvs6.9d;GCS6～12:8.2dvs10.3d,P<0.01)。结论对于高血压脑出血拟行微创治疗的患者行早期经鼻气管插管可明显减轻术后肺部并发症,减少ICU治疗时间,减轻患者经济负担,促进康复。     

Markov modeling of minimally invasive surgery based on tool/tissue interaction and force/torque signatures for evaluating surgical skills

The best method of training for laparoscopic surgical skills is controversial. Some advocate observation in the operating room, while others promote animal and simulated models or a combination of surgery-related tasks. A crucial process in surgical education is to evaluate the level of surgical skills. For laparoscopic surgery, skill evaluation is traditionally performed subjectively by experts grading a video of a procedure performed by a student. By its nature, this process uses fuzzy criteria. The objective of the current study was to develop and assess a skill scale using Markov models (MMs). Ten surgeons [five novice surgeons (NS); five expert surgeons (ES)] performed a cholecystectomy and Nissen fundoplication in a porcine model. An instrumented laparoscopic grasper equipped with a three-axis force/torque (F/T) sensor was used to measure the forces/torques at the hand/tool interface synchronized with a video of the tool operative maneuvers. A synthesis of frame-by-frame video analysis and a vector quantization algorithm, allowed to define F/T signatures associated with 14 different types of tool/tissue interactions. The magnitude of F/T applied by NS and ES were significantly different (p < 0.05) and varied based on the task being performed. High F/T magnitudes were applied by NS compared with ES while performing tissue manipulation and vise versa in tasks involved tissue dissection. From each step of the surgical procedures, two MMs were developed representing the performance of three surgeons out of the five in the ES and NS groups. The data obtained by the remaining two surgeons in each group were used for evaluating the performance scale. The final result was a surgical performance index which represented a ratio of statistical similarity between the examined surgeon's MM and the MM of NS and ES. The difference between the performance index value, for a surgeon under study, and the NS/ES boundary, indicated the level of expertise in the surgeon's own group. Using this index, 87.5% of the surgical procedures were correctly classified into the NS and ES groups. The 12.5% of the procedures that were misclassified were performed by the ES and classified as NS. However in these cases the performance index values were very close to the NS/ES boundary. Preliminary data suggest that a performance index based on MM and F/T signatures provides an objective means of distinguishing NS from ES. In addition, this methodology can be further applied to evaluate haptic virtual reality surgical simulators for improving realism in surgical education.     

Integration of a miniaturised triaxial force sensor in a minimally invasive surgical tool

This paper reports preliminary results on design and fabrication of a cutting tool with an integrated triaxial force sensor to be applied in fetal surgery procedures. The outer diameter of the proposed device is 7.4 mm, but a scaled down design can be easily achieved. Linearity and hysteresis tests have been performed for both normal and tangential loadings. A linear transformation relating the sensor output to the external applied force is introduced and discussed. The typical working range for the conceived instrument is around 0.3 N, while 20 N and 1 N are, respectively, maximum normal and tangential forces for which the device robustness has been assessed.     

Dynamic 3-D virtual fixtures for minimally invasive beating heart procedures

Two-dimensional or 3-D visual guidance is often used for minimally invasive cardiac surgery and diagnosis. This visual guidance suffers from several drawbacks such as limited field of view, loss of signal from time to time, and in some cases, difficulty of interpretation. These limitations become more evident in beating-heart procedures when the surgeon has to perform a surgical procedure in the presence of heart motion. In this paper, we propose dynamic 3-D virtual fixtures (DVFs) to augment the visual guidance system with haptic feedback, to provide the surgeon with more helpful guidance by constraining the surgeon's hand motions thereby protecting sensitive structures. DVFs can be generated from preoperative dynamic magnetic resonance (MR) or computed tomograph (CT) images and then mapped to the patient during surgery. We have validated the feasibility of the proposed method on several simulated surgical tasks using a volunteer's cardiac image dataset. Validation results show that the integration of visual and haptic guidance can permit a user to perform surgical tasks more easily and with reduced error rate. We believe this is the first work presented in the field of virtual fixtures that explicitly considers heart motion.     

A coaxial antenna with miniaturized choke for minimally invasive interstitial heating

We present a new coaxial antenna for microwave interstitial coagulative therapy, working at 2450 MHz and endowed with a miniaturized sleeve choke in order to reduce back heating effects and make the system response less dependent on the antenna insertion depth into the tissue; the way the choke is implemented makes the overall transversal size minimum and allows small adjustments of the choke section length even during operation. We describe the main technical features of the antenna and show experimental results clearly proving the choke effectiveness. Numerical simulations well agree with experimental data, confirming the suitability of the proposed device for minimally invasive medical applications.     

Pinpoint injection of microtools for minimally invasive micromanipulation of microbe by laser trap

This paper reports transportation of the target microbe by the laser trapped microtools with minimum laser irradiation to the target. The size of a microtool (MT) is around micrometer. The MTs are manipulated by the focused laser under the microscope to manipulate the target microbe. Here we propose a pinpoint injection method of MTs at the desired location in the microchamber, which is filled with liquid. At first, we classified the injection method of the MTs in four categories. Here we employed a new method to install the MTs inside the microchamber. We developed a MT holding chip to install the MTs. The MTs were injected in the microchamber, and were manipulated successfully by the laser scanning micromanipulator to transport the target microbe for separation. The proposed method is useful for the pinpoint injection of MTs and separation by the indirect micromanipulation.     

Intraoperative laparoscope augmentation for port placement and resection planning in minimally invasive liver resection

In recent years, an increasing number of liver tumor indications were treated by minimally invasive laparoscopic resection. Besides the restricted view, two major intraoperative issues in laparoscopic liver resection are the optimal planning of ports as well as the enhanced visualization of (hidden) vessels, which supply the tumorous liver segment and thus need to be divided (e.g., clipped) prior to the resection. We propose an intuitive and precise method to plan the placement of ports. Preoperatively, self-adhesive fiducials are affixed to the patient's skin and a computed tomography (CT) data set is acquired while contrasting the liver vessels. Immediately prior to the intervention, the laparoscope is moved around these fiducials, which are automatically reconstructed to register the patient to its preoperative imaging data set. This enables the simulation of a camera flight through the patient's interior along the laparoscope's or instruments' axes to easily validate potential ports. Intraoperatively, surgeons need to update their surgical planning based on actual patient data after organ deformations mainly caused by application of carbon dioxide pneumoperitoneum. Therefore, preoperative imaging data can hardly be used. Instead, we propose to use an optically tracked mobile C-arm providing cone-beam CT imaging capability intraoperatively. After patient positioning, port placement, and carbon dioxide insufflation, the liver vessels are contrasted and a 3-D volume is reconstructed during patient exhalation. Without any further need for patient registration, the reconstructed volume can be directly augmented on the live laparoscope video, since prior calibration enables both the volume and the laparoscope to be positioned and oriented in the tracking coordinate frame. The augmentation provides the surgeon with advanced visual aid for the localization of veins, arteries, and bile ducts to be divided or sealed.