Vision-based markerless registration using stereo vision and an augmented reality surgical navigation system: a pilot study.

Background: This study evaluated the use of an augmented reality navigation system that provides a markerless registration system using stereo vision in oral and maxillofacial surgery.

Method: A feasibility study was performed on a subject, wherein a stereo camera was used for tracking and markerless registration. The computed tomography data obtained from the volunteer was used to create an integral videography image and a 3-dimensional rapid prototype model of the jaw.

Real-time in situ three-dimensional integral videography and surgical navigation using augmented reality: a pilot study.

To evaluate the feasibility and accuracy of a three-dimensional augmented reality system incorporating integral videography for imaging oral and maxillofacial regions, based on preoperative computed tomography data. Three-dimensional surface models of the jawbones, based on the computed tomography data, were used to create the integral videography images of a subject's maxillofacial area. The three-dimensional augmented reality system (integral videography display, computed tomography, a position tracker and a computer) was used to generate a three-dimensional overlay that was projected on the surgical site via a half-silvered mirror.

Developing essential rigid-flexible outer sheath to enable novel multi-piercing surgery.

We have developed a new generation device called rigid-flexible outer sheath with multi-piercing surgery (MPS) to solve the issues of tissue closure, triangulation, and platform stability in natural orifice transluminal endoscopic surgery (NOTES), and the problems of restricted visual field, organ damage, and removing a resected organ from body in needlescopic surgery (NS). The shape of the flexible outer sheath can be selectively locked by a novel pneumatic shapelocking mechanism. Major features include four directional flexion at the distal end, four working channels, and suction and water jet functions.

3-D endoscope using a single CCD camera and pneumatic vibration mechanism.

Background: During endoscopic surgical procedures, surgeons must manipulate an endoscope inside the body cavity to observe a surgical area while estimating the distance between that area and the surgical instruments by reference to a monitor on which the movement and size of the surgical instruments are displayed in 2-D endoscopic images. Therefore, there is a risk of the endoscope or instruments physically damaging body tissues. To overcome this problem, we developed a Ø5-mm, 3-D endoscope using a single 1/10-inch CCD camera and pneumatic vibration mechanism.

Magnetic resonance imaging-compatible tactile sensing device based on a piezoelectric array.

Minimally invasive surgery is a widely used medical technique, one of the drawbacks of which is the loss of direct sense of touch during the operation. Palpation is the use of fingertips to explore and make fast assessments of tissue morphology. Although technologies are developed to equip minimally invasive surgery tools with haptic feedback capabilities, the majority focus on tissue stiffness profiling and tool-tissue interaction force measurement.

Surgical tool alignment guidance by drawing two cross-sectional laser-beam planes.

Conventional surgical navigation requires for surgeons to move their sight and conscious off the surgical field when checking surgical tool's positions shown on the display panel. Since that takes high risks of surgical exposure possibilities to the patient's body, we propose a novel method for guiding surgical tool position and orientation directly in the surgical field by a laser beam. In our navigation procedure, two cross-sectional planar laser beams are emitted from the two laser devices attached onto both sides of an optical localizer, and show surgical tool's entry position on the patient's body surface and its orientation on the side face of the surgical tool.

A beam-splitter-type 3-D endoscope for front view and front-diagonal view images.

Purpose: In endoscopic surgery, surgeons must manipulate an endoscope inside the body cavity to observe a large field-of-view while estimating the distance between surgical instruments and the affected area by reference to the size or motion of the surgical instruments in 2-D endoscopic images on a monitor. Therefore, there is a risk of the endoscope or surgical instruments physically damaging body tissues. To overcome this problem, we developed a Ø7- mm 3-D endoscope that can switch between providing front and front-diagonal view 3-D images by simply rotating its sleeves.

Nonmetallic rigid-flexible outer sheath with pneumatic shapelocking mechanism and double curvature structure.

Single port access (SPA) surgery is a laparoscopic procedure using only one transumbilical-placed port. Natural orifice transluminal endoscopic surgery (NOTES) offers the possibility of surgery without visible scars. To address the access and stability problems in SPA and NOTES, we developed a device called rigid-flexible outer sheath.

Augmented reality system for oral surgery using 3D auto stereoscopic visualization.

We present an augmented reality system for oral and maxillofacial surgery in this paper. Instead of being displayed on a separated screen, three-dimensional (3D) virtual presentations of osseous structures and soft tissues are projected onto the patient's body, providing surgeons with exact knowledge of depth information of high risk tissues inside the bone. We employ a 3D integral imaging technique which produce motion parallax in both horizontal and vertical direction over a wide viewing area in this study.

Endoscope system with plasma flushing and coaxial round jet nozzle for off-pump cardiac surgery.

Background: To develop a new endoscope for performing simple surgical tasks inside the blood-filled cardiac atrium/chamber, that is, "off-pump" cardiac surgeries.

Methods: We developed the endoscope system with plasma flushing and coaxial round jet nozzle. The "plasma flushing" system was invented to observe the interior of the blood-filled heart by displacing blood cells in front of the endoscope tip.

Autostereoscopic 3D Display with Long Visualization Depth Using Referential Viewing Area-Based Integral Photography.

We developed an autostereoscopic display for distant viewing of 3D computer graphics (CG) images without using special viewing glasses or tracking devices. The images are created by employing referential viewing area-based CG image generation and pixel distribution algorithm for integral photography (IP) and integral videography (IV) imaging. CG image rendering is used to generate IP/IV elemental images.

A new, safer, controllable field-of-view endoscope avoiding movement inside body cavities.

One of the greatest difficulties in endoscopic surgery is the limited field-of-view (FOV) of endoscopes. During endoscopic manipulation in body cavities to expand the FOV, there is the risk of inadvertent damage to body tissues, nerves, and internal organs. The risk increases especially in surgery that is performed inside a very small cavity, or in which body tissues are very fragile.

3-D augmented reality for MRI-guided surgery using integral videography autostereoscopic image overlay.

A 3-D augmented reality navigation system using autostereoscopic images was developed for MRI-guided surgery. The 3-D images are created by employing an animated autostereoscopic image, integral videography (IV), which provides geometrically accurate 3-D spatial images and reproduces motion parallax without using any supplementary eyeglasses or tracking devices. The spatially projected 3-D images are superimposed onto the surgical area and viewed via a half-silvered mirror.

Precision-guided surgical navigation system using laser guidance and 3D autostereoscopic image overlay.

This paper describes a precision-guided surgical navigation system for minimally invasive surgery. The system combines a laser guidance technique with a three-dimensional (3D) autostereoscopic image overlay technique. Images of surgical anatomic structures superimposed onto the patient are created by employing an animated imaging method called integral videography (IV), which can display geometrically accurate 3D autostereoscopic images and reproduce motion parallax without the need for special viewing or tracking devices.

Novel endoscope system with plasma flushing for off-pump cardiac surgery.

The purpose of this study is to develop a new endoscope for performing simple surgical tasks inside a cardiac atrium/chamber filled with blood, i.e., for performing "off-pump" cardiac surgeries.

Nonmagnetic rigid and flexible outer sheath with pneumatic interlocking mechanism for minimally invasive surgical approach.

We developed a nonmagnetic rigid and flexible outer sheath with pneumatic interlocking mechanism using flexible toothed links and a wire-driven bending distal end. The outer sheath can be switched between rigid and flexible modes easily depending on surgical scenes, and the angle of its distal end can be controlled by three nylon wires. All components of flexible parts are made of MRI-compatible nonmagnetic plastics.

A coaxial laser endoscope with arbitrary spots in endoscopic view for fetal surgery.

In this paper, we describe a rigid endoscope that transmits a laser beam coaxially to arbitrary points in the endoscopic view, mainly for treatment of twin-to-twin transfusion syndrome. The endoscope consists of a hotmirror for coaxial transmission of visible light and a Nd:YAG laser beam, and galvanometers for controlling the beam irradiation angle. We evaluated the transmission efficiency of the laser power, the spot size through the endoscope and accuracy in positioning the beam.

R-PLUS: a Riemannian anisotropic edge detection scheme for vascular segmentation.

In this paper, detection of edges in oriented fields is addressed. In some applications such as vessel segmentation because of the intrinsic orientation of the structures, edge detection is only demanded in a particular subspace. This is specially usefull when a curve evolution is chosen for segmentation since gradients in parallel to vessel orientation may stop the contour.

Fetus-supporting flexible manipulator with balloon-type stabilizer for endoscopic intrauterine surgery.

Background: Minimally invasive endoscopic fetal surgery enables intrauterine intervention with reduced risk to the mother and fetus. A novel surgical manipulator is described for stabilizing the fetus and restraining it from floating free during endoscopic intrauterine surgery.

Methods: We designed and fabricated a prototype fetus-supporting manipulator equipped with flexible joint and bending mechanisms and a soft balloon stabilizer.

A variational method for geometric regularization of vascular segmentation in medical images.

In this paper, a level-set-based geometric regularization method is proposed which has the ability to estimate the local orientation of the evolving front and utilize it as shape induced information for anisotropic propagation. We show that preserving anisotropic fronts can improve elongations of the extracted structures, while minimizing the risk of leakage. To that end, for an evolving front using its shape-offset level-set representation, a novel energy functional is defined.

Adaptive 4D MR imaging using navigator-based respiratory signal for MRI-guided therapy.

For real-time 3D visualization of respiratory organ motion for MRI-guided therapy, a new adaptive 4D MR imaging method based on navigator echo and multiple gating windows was developed. This method was designed to acquire a time series of volumetric 3D images of a cyclically moving organ, enabling therapy to be guided by synchronizing the 4D image with the actual organ motion in real time. The proposed method was implemented in an open-configuration 0.

Effective statistical edge integration using a flux maximizing scheme for volumetric vascular segmentation in MRA.

Evolutionary schemes based on the level set theory are effective tools for medical image segmentation. In this paper, a new variational technique for edge integration is presented. Region statistical measures and orientation information from ramp-like edges, are fused within an energy minimization scheme that is based on a new interpretation of edge concept.

Improved viewing resolution of integral videography by use of rotated prism sheets.

We demonstrated that placing a pair of prism sheets in front of a display and rotating them overcomes the upper resolution limit of Integral Photograpy (IP) / Integral Videography (IV) imposed by the Nyquist sampling theorem. A pair of prism sheet with the same pitch placed in front of an IP or IV display parallel-shifts the light rays in the 3D space. Rotating the pair shifts the light rays, causing them to appear to rotate around their original positions.

Rigid-flexible outer sheath model using slider linkage locking mechanism and air pressure for endoscopic surgery.

The objective of this paper is to develop an outer sheath for flexible endoscopic manipulators. This sheath can switch two states including flexible and rigid, and make a rigid curved path for inserting manipulators. The flexible mode can be curved into a required shape.