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Antimicrobial peptides (AMPs) have started to garner more interest as novel antimicrobial agents. The scorpion venom peptide ctry2459 was modified to CT-K3K7 by lysine substitutions at the 3rd and 7th positions to increase the cationic properties. We discovered that the modified peptides CT-K3K7 had improved antibacterial activity, higher thermal stability, as well as lower hemolytic activity. It can kill S. aureus and P. aeruginosa rapidly, and reduce the production of biofilm and live bacterial residues in biofilm in vitro. CT-K3K7 has also been demonstrated to decrease bacterial counts, abscess area, and inflammatory cell infiltration in the mouse subcutaneous abscess models that were duplicated by S. aureus and P. aeruginosa. CT-K3K7 has difficulty in inducing S. aureus and P. aeruginosa to develop drug resistance, which may be related to the bactericidal properties. CT-K3K7 increases cationic properties by lysine substitutions can increase the electrostatic force between the peptides and the bacterial surface, which can lead to an increase in bacterial membrane permeability and DNA binding. In conclusion, the modified peptide CT-K3K7 enhances the antimicrobial activity and can be a novel antimicrobial agent candidate for the treatment of infections by S. aureus and P. aeruginosa.

Antimicrobial peptides (AMPs) have gained interest as a new type of antimicrobial agent. Scorpion venom peptide ctry2459 were modified to CT-K3K7 by lysine substitutions at position 3rd and 7th. We found that the modified peptides CT-K3K7 with improved antibacterial activity, higher thermal stability and lower hemolytic activity. It can rapidly kill S. aureus and P. aeruginosa, reduce the production of biofilm and live bacteria residues in biofilm in vitro. CT-K3K7 has also been demonstrated that could decrease the bacterial counts in the subcutaneous abscess region, abscess area, and inflammatory cell infiltration in mouse subcutaneous abscess models duplicated by S. aureus and P. aeruginosa. CT-K3K7 is difficult to induce S. aureus and P. aeruginosa to develop drugs resistance, which may be related to the bactericidal way that the increase of cationic properties by lysine substitutions can increase the electrostatic force between the peptides and the bacterial surface that lead to the increase of bacterial membrane permeability and DNA binding. In conclusion, the modified peptide CT-K3K7 enhanced antimicrobial activity and can be as a new antimicrobial agent candidate for the treatment of infections by S. aureus and P. aeruginosa.

A liquid-metal based capacitive soft pressure microsensor is proposed in this work for measuring pressure in microchannels. To measure the pressure of the target microchannel, a short detection channel is fabricated and connected to the target microchannel. Because the detection channel has only one outlet at the end which is connected to the target microchannel, the fluid in the detection channel will stay still during the measurement and the pressure remains constant inside the detection channel. A segment of reference fluid which is immiscible with the working fluid is sealed inside the detection channel. Because the chip material is soft, the pressure change will lead to the movement of the interface between the reference fluid and working fluid inside the detection channel. A pair of liquid metal electrodes are fabricated on both sides of the detection channel. By measuring the capacitance between these two liquid metal electrodes, the movement of the interface can be detected, and thus the pressure change can be detected as well. To minimize the influence from the environment, two liquid metal shield layers are placed on the top and the bottom of the microchannel layer separately. The microsensor was first tested in a microfluidic system and then utilized to measure the blood pressure of rabbit carotid artery in vivo. The experimental results showed excellent stability and linear correlation between capacitance and the value of fluid pressure. The pressure sensor can achieve a resolution of 7.5 mmHg within a pressure range of 20-300 mmHg. This work provides a promising approach to develop an implantable blood or intraocular pressure-monitoring device for clinical use.

BACKGROUND We aimed to assess the feasibility of a video-augmented fluoroscopy (VAF) technique using a camera-augmented mobile C-arm (CamC) for distal interlocking of intramedullary nails. METHODS Three surgeons performed distal interlocking on seven pairs of cadaveric bovine carpal bones using the VAF system and conventional fluoroscopy. We compared radiation exposure, procedure time, and drilling quality between the VAF system and conventional fluoroscopic guidance. RESULTS Distal interlocking using VAF significantly reduced the number of fluoroscopic images compared with conventional fluoroscopy (P

Die intraoperative Anwendung von „augmented reality“ (AR, erweiterte Realitat) fand bisher uberwiegend im Bereich der Endoskopie statt. Dabei wurde das Kamerabild des Endoskops mittels aufwendig errechneter Darstellungen praoperativer Bildgebung erweitert. Aufgrund des hohen Aufwands und der Komplexitat der Systeme hat sich die Technologie bisher nicht durchsetzen konnen. Der „Camera Augmented Mobile C-arm“ (CamC), der einen herkommlichen C-Bogen durch eine Videokamera erweitert, zeichnet sich durch eine unkomplizierte Handhabung aus. Er bettet das Rontgenbild geometrisch exakt in das Videolivebild ein. Die klinische Anwendung in 43 Fallen zeigte die Starken des Gerates bei der Positionierung, der Inzisionsplanung, der Kirschner-Drahteinbringung und der Instrumentenfuhrung anhand der neuartigen Visualisierung. Aufgrund der neuen Funktionen und der einfachen Integration in jeden Eingriff, der einen Bildwandler benotigt, hat der CamC ein groses Potential, die erste AR-Technologie in der Unfallchirurgie und Orthopadie zu werden.

During surgery, the surgeon’s view of the patient is complemented with imaging that provides an indirect visual feedback of the treated anatomy. For an advanced visualization, existing image-guided surgical systems employ tracking and registration methods to fuse medical images. Lately, medical augmented reality has enabled in situ visualization by registering three-dimensional preoperative data (e.g. CT, MRI, and PET) with two-dimensional intraoperative images (e.g. X-ray, Ultrasound, and Optics). Including the virtual locations of the surgical instruments within the visualization provides the most intuitive way to facilitate surgical navigation since the surgeon mental mapping between medical images, instruments, and patient is not necessary anymore. This book chapter investigates medical augmented reality solutions within orthopaedics and highlights the innovations that lead surgeons in surgical planning, navigation, and education in an efficient and timely manner.

Background In orthopaedic trauma surgery, image-guided procedures are mostly based on fluoroscopy. The reduction of radiation exposure is an important goal. The purpose of this work was to investigate the impact of a camera-augmented mobile C-arm (CamC) on radiation exposure and the surgical workflow during a first clinical trial. Methods Applying a workflow-oriented approach, 10 general workflow steps were defined to compare the CamC to traditional C-arms. The surgeries included were arbitrarily identified and assigned to the study. The evaluation criteria were radiation exposure and operation time for each workflow step and the entire surgery. The evaluation protocol was designed and conducted in a single-centre study. Results The radiation exposure was remarkably reduced by 18 X-ray shots 46% using the CamC while keeping similar surgery times. Conclusions The intuitiveness of the system, its easy integration into the surgical workflow, and its great potential to reduce radiation have been demonstrated.

The interlocking of intramedullary nails is a technically demanding procedure which involves a considerable amount of X-ray acquisitions; one study lists as many as 48 to successfully complete the procedure and fix screws into 4–6 mm distal holes of the nail. We propose to design an augmented radiolucent drill to assist surgeons in completing the distal locking procedure without any additional X-ray acquisitions. Using an augmented reality fluoroscope that coregisters optical and X-ray images, we exploit solely the optical images to detect the augmented radiolucent drill and estimate its tip position in real-time. Consequently, the surgeons will be able to maintain the down the beam positioning required to drill the screws into the nail holes successfully. To evaluate the accuracy of the proposed augmented drill, we perform a preclinical study involving six surgeons and ask them to perform distal locking on dry bone phantoms. Surgeons completed distal locking 98.3% of the time using only a single X-ray image with an average navigation time of 1.4 $\pm$ 0.9 min per hole.

2D/3D image fusion applications are widely used in endovascular interventions. Complaints from interventionists about existing state-of-art visualization software are usually related to the strong compromise between 2D and 3D visibility or the lack of depth perception. In this paper, we investigate several concepts enabling improvement of current image fusion visualization found in the operating room. First, a contour enhanced visualization is used to circumvent hidden information in the X-ray image. Second, an occlusion and depth color-coding scheme is considered to improve depth perception. To validate our visualization technique both phantom and clinical data are considered. An evaluation is performed in the form of a questionnaire which included 24 participants: ten clinicians and fourteen non-clinicians. Results indicate that the occlusion correction method provides 100% correctness when determining the true position of an aneurysm in X-ray. Further, when integrating an RGB or RB color-depth encoding in the image fusion both perception and intuitiveness are improved.

The alignment of the lower limb in high tibial osteotomy (HTO) or total knee arthroplasty (TKA) must be determined intraoperatively. One way to do so is to deform the mechanical axis deviation (MAD), for which a tolerance measurement of 10 mm is widely accepted. Many techniques are proposed in clinical practice such as visual inspection, cable method, grid with lead impregnated reference lines, or more recently, navigation systems. Each has their disadvantages including reliability of the MAD measurement, excess radiation, prolonged operation time, complicated setup and high cost. To alleviate such shortcomings, we propose a novel clinical protocol that allows quick and accurate intraoperative calculation of MAD. This is achieved by an X-ray stitching method requiring only three X-ray images placed into a panoramic image frame during the entire procedure. The method has been systematically analyzed in a simulation framework in order to investigate its accuracy and robustness. Furthermore, we validated our protocol via a preclinical study comprising 19 human cadaver legs. Four surgeons determined MAD measurements using our X-ray panorama and compared these values to a gold-standard CT-based technique. The maximum average MAD error was 3.5mm which shows great potential for the technique.

Visualizing 2D and 3D anatomical information simultaneously within an X-ray image is challenging. Multiple monitors are required in the operating room to enable visualization of anatomical data by the surgeon. Consequently, this results in an interruption during the operation for proper assessment of information. In this paper, we introduce an interactive visualization of the 3D data from new perspectives including visualizing a virtual mirror from the same viewpoint as the X-ray source. The main contribution is our development of a complete angiographic visualization system that displays simultaneous 2D X-ray and 3D anatomical information in a common monitor for the surgeon in the operating room. No previous works have conceived the integration of the virtual mirror into the projection geometry of a C-arm fluoroscope. In total, 24 participants were asked to assess the benefits of the angiographic virtual mirror with different colour-depth encodings. The results of our feasibility study show a clear improvement when deciphering the true positions of aneurysms in X-ray. Lastly, color depth encoding improves correspondence between the 3D vasculature displayed in the virtual mirror to their projection images in X-ray.

A high accuracy temperature sensor integrated in TPMS with an inaccuracy of ±1°C from −55°C to 125 °C is realized in a standard CMOS process. The errors due to finite op-amp gain, offset voltage and 1/f noise are eliminated with correlated double sampling technique. The temperature-dependent voltage is boosted by a switched capacitor low noise amplifier and digitalized with an incremental ADC of a resolution about 13bits. Furthermore, 2-bits coarse biased current trimming and 5-bits fine resistive-array trimming are applied to calibrate the process variation. The required accuracy is obtained after the calibration at single temperature point. Additionally, the second-order nonlinearity temperature compensation algorithm for piezoresistive pressure sensor is described. Finally, experimental results are provided to verify the effectiveness of the proposed topology.

The camera-augmented mobile C-arm (CamC) augments any mobile C-arm by a video camera and mirror construction and provides a co-registration of X-ray with video images. The accurate overlay between these images is crucial to high-quality surgical outcomes. In this work, we propose a practical solution that improves the overlay accuracy for any C-arm orientation by: (i) improving the existing CamC calibration, (ii) removing distortion effects, and (iii) accounting for the mechanical sagging of the C-arm gantry due to gravity.A planar phantom is constructed and placed at different distances to the image intensifier in order to obtain the optimal homography that co-registers X-ray and video with a minimum error. To alleviate distortion, both X-ray calibration based on equidistant grid model and Zhang's camera calibration method are implemented for distortion correction. Lastly, the virtual detector plane (VDP) method is adapted and integrated to reduce errors due to the mechanical sagging of the C-arm gantry.The overlay errors are 0.38±0.06 mm when not correcting for distortion, 0.27±0.06 mm when applying Zhang's camera calibration, and 0.27±0.05 mm when applying X-ray calibration. Lastly, when taking into account all angular and orbital rotations of the C-arm, as well as correcting for distortion, the overlay errors are 0.53±0.24 mm using VDP and 1.67±1.25 mm excluding VDP.The augmented reality fluoroscope achieves an accurate video and X-ray overlay when applying the optimal homography calculated from distortion correction using X-ray calibration together with the VDP.

In the current clinical workflow of endovascular abdominal aortic repairs (EVAR) a stent graft is inserted into the aneurysmatic aorta under 2D angiographic imaging. Due to the missing depth information in the X-ray visualization, it is highly difficult in particular for junior physicians to place the stent graft in the preoperatively defined position within the aorta. Therefore, advanced 3D visualization of stent grafts is highly required. In this paper, we present a novel algorithm to automatically match a 3D model of the stent graft to an intraoperative 2D image showing the device. By automatic preprocessing and a global-to-local registration approach, we are able to abandon user interaction and still meet the desired robustness. The complexity of our registration scheme is reduced by a semi-simultaneous optimization strategy incorporating constraints that correspond to the geometric model of the stent graft. Via experiments on synthetic, phantom, and real interventional data, we are able to show that the presented method matches the stent graft model to the 2D image data with good accuracy.

In this paper, we present an interactive X-Ray perceptual visualization technique (IXPV) to improve 3D perception in standard single-view X-Ray images. Based on a priori knowledge from CT data, we re-introduce lost depth information into the original single-view X-Ray image without jeopardizing information of the original X-Ray. We propose a novel approach that is suitable for correct fusion of intraoperative X-Ray and ultrasound, co-visualization of X-Ray and surgical tools, and for improving the 3D perception of standard radiographs. Phantom and animal cadaver datasets were used during experimentation to demonstrate the impact of our technique. Results from a questionnaire completed by 11 clinicians and computer scientists demonstrate the added value of introduced depth cues directly in an X-Ray image. In conclusion, we propose IXPV as a futuristic alternative to the standard radiographic image found in today's clinical setting.

We propose a novel method to compute the poses of randomly positioned square markers in one world coordinate frame from multiple camera views, by taking the predicted accuracy of the camera pose estimation for each marker into account. The problem of computing the best closed-form solution of the world pose of each marker is modeled as all-pair shortest path problem in graph theory. The computed world poses are further optimized by minimizing the geometric distances in images. Experimental results show that incorporating the predicted accuracy of the pose estimation for each marker yields constant high quality calibration results independent of the order of image sequences compared to cases when this knowledge is not used.

In this paper, we present a novel method to create parallax-free panoramic X-ray images of long bones during surgery by making the C-arm rotate around its X-ray source, relative to the patient's table. In order to ensure that the C-arm motion is a relative pure rotation around its X-ray source, we move the table to compensate for the translational part of the motion based on C-arm pose estimation, for which we employed a Camera Augmented Mobile C-arm system and a visual planar marker pattern. Thus, we are able to produce a parallax-free panoramic X-ray image that preserves the property of linear perspective projection. We additionally implement a method to reduce the error caused by varying intrinsic parameters of C-arm X-ray imaging. The results show that our proposed method can generate a parallax-free panoramic X-ray image, independent of the configuration of bone structures and without the requirement of a fronto-parallel setup or any overlap in the X-ray images. The resulting panoramic images have a negligible difference (below 2 pixels) in the overlap between two consecutive individual X-ray images and have a high visual quality, which promises suitability for intra-operative clinical applications in orthopedic and trauma surgery.

In this paper, we propose a novel method to generate panoramic X-ray images intra-operatively by using the previously introduced Camera Augmented Mobile C-arm by Navab et al. [1]. This advanced mobile C-arm system acquires registered X-ray and optical images by construction, which facilitates the generation of panoramic X-ray images based on the motion estimation of the X-ray source. Visual marker tracking is employed to estimate the camera motion and this estimated motion is also applied to the X-ray source. Our proposed method is suitable and practical for intra-operative usage generating panoramic X-ray images without the requirement of a fronto-parallel setup and overlapping X-ray images. The results show that the panoramic X-ray images generated by our method are accurate enough (errors less than 1%) for metric measurements. We will demonstrate initial results of intra-operative clinical application in trauma surgery.

X-ray images are widely used during surgery for long bone fracture fixation. Mobile C-arms provide X-ray images which are used to determine the quality of trauma reduction, i.e. the extremity length and mechanical axis of long bones. Standard X-ray images have a narrow field of view and can not visualize the entire long bone on a single image. In this paper, we propose a novel method to generate panoramic X-ray images in real time by using the previously introduced Camera Augmented Mobile C-arm. This advanced mobile C-arm system acquires registered X-ray and optical images by construction, which facilitates the generation of panoramic X-ray images based on first stitching the optical images and then embedding the X-ray images. We additionally introduce a method to reduce the parallax effect that leads to the blurring and measurement error on panoramic X-ray images. Visual marker tracking is employed to automatically stitch the sequence of video images and to rectify images. Our proposed method is suitable for intra-operative usage generating panoramic X-ray images, which enable metric measurements, with less radiation and without requirement of fronto-parallel setup and overlapping X-ray images. The results show that the panoramic X-ray images generated by our method are accurate enough (errors less than 1%) for metric measurements and suitable for many clinical applications in trauma reduction.

Researchers are developing augmented reality visualization systems to provide accessible and user-friendly interfaces for medical intervention and patient information systems. A related video can be seen here: http://youtu.be/kifj0ZP4Mos. It shows how augmented reality visualization systems can provide accessible and user-friendly interfaces for medical intervention and patient information systems.