Kozo Konishi

Construct validity for eye-hand coordination skill on a virtual reality laparoscopic surgical simulator.

BackgroundThis study was carried out to investigate whether eye-hand coordination skill on a virtual reality laparoscopic surgical simulator (the LAP Mentor) was able to differentiate among subjects with different laparoscopic experience and thus confirm its construct validity.MethodsA total of 31 surgeons, who were all right-handed, were divided into the following two groups according to their experience as an operator in laparoscopic surgery: experienced surgeons (more than 50 laparoscopic procedures) and novice surgeons (fewer than 10 laparoscopic procedures). The subjects were tested using the eye-hand coordination task of the LAP Mentor, and performance was compared between the two groups. Assessment of the laparoscopic skills was based on parameters measured by the simulator.ResultsThe experienced surgeons completed the task significantly faster than the novice surgeons. The experienced surgeons also achieved a lower number of movements (NOM), better economy of movement (EOM) and faster average speed of the left instrument than the novice surgeons, whereas there were no significant differences between the two groups for the NOM, EOM and average speed of the right instrument.ConclusionsEye-hand coordination skill of the nondominant hand, but not the dominant hand, measured using the LAP Mentor was able to differentiate between subjects with different laparoscopic experience. This study also provides evidence of construct validity for eye-hand coordination skill on the LAP Mentor.

Intraoperative Magnetic Tracker Calibration Using a Magneto-Optic Hybrid Tracker for 3-D Ultrasound-Based Navigation in Laparoscopic Surgery

This paper describes a ultrasound (3D US) system that aims to achieve augmented reality (AR) visualization during laparoscopic surgery, especially for the liver. To acquire 3D US data of the liver, the tip of a laparoscopic ultrasound probe is tracked inside the abdominal cavity using a magnetic tracker. The accuracy of magnetic trackers, however, is greatly affected by magnetic field distortion that results from the close proximity of metal objects and electronic equipment, which is usually unavoidable in the operating room. In this paper, we describe a calibration method for intraoperative magnetic distortion that can be applied to laparoscopic 3D US data acquisition; we evaluate the accuracy and feasibility of the method by in vitro and in vivo experiments. Although calibration data can be acquired freehand using a magneto-optic hybrid tracker, there are two problems associated with this method - error caused by the time delay between measurements of the optical and magnetic trackers, and instability of the calibration accuracy that results from the uniformity and density of calibration data. A temporal calibration procedure is developed to estimate the time delay, which is then integrated into the calibration, and a distortion model is formulated by zeroth-degree to fourth-degree polynomial fitting to the calibration data. In the in vivo experiment using a pig, the positional error caused by magnetic distortion was reduced from 44.1 to 2.9 mm. The standard deviation of corrected target positions was less than 1.0 mm. Freehand acquisition of calibration data was performed smoothly using a magneto-optic hybrid sampling tool through a trocar under guidance by realtime 3-D monitoring of the tool trajectory; data acquisition time was less than 2 min. The present study suggests that our proposed method could correct for magnetic field distortion inside the patients abdomen during a laparoscopic procedure within a clinically permissible period of time, as well as enabling an accurate 3D US reconstruction to be obtained that can be superimposed onto live endoscopic images.

A Motion Adaptable Needle Placement Instrument Based on Tumor Specific Ultrasonic Image Segmentation

This paper suggests an ultrasound guided needle insertion instrument which can track target motion in real-time. Under traditional ultrasound guided needle insertion therapies, surgeons have had much burden to find out the precise targeting position, particularly when the organ is moving due to the respiration or heartbeat. We developed a new needle insertion instrument which can track moving target based on visual servo control. In addition, this paper proposed a tumor specific active contour model which can conduct a fast and robust segmentation for tumor, and utilized Hough transform for needle recognition. In the experiment, the proposed system could track a moving phantom successfully at speed of 3 frames/sec processing.

3D Ultrasound System Using a Magneto-optic Hybrid Tracker for Augmented Reality Visualization in Laparoscopic Liver Surgery

A three-dimensional ultrasound (3D-US) system suitable for laparoscopic surgery that uses a novel magneto-optic hybrid tracker configuration. Our aim is to integrate 3D-US into a laparoscopic AR system. A 5D miniature magnetic tracker is combined with a 6D optical tracker outside the body to perform 6D tracking of a flexible US probe tip in the abdominal cavity. 6D tracking parameters at the tip are obtained by combining the 5D parameters at the tip inside the body, the 6D parameters at the US probe handle outside the body, and the restriction of the tip motion relative to the handle. The system was evaluated in comparison with a conventional 3D ultrasound system. Although the accuracy of the proposed system was somewhat inferior to that of the conventional one, both the accuracy and sweet spot area were found to be acceptable for clinical use.

Objective assessment of laparoscopic suturing skills using a motion-tracking system

BackgroundLaparoscopic suturing skills are important for advanced laparoscopic surgery. However, objective assessment of these skills has not yet been established. The aim of this study was to assess the laparoscopic suturing skills of novice and experienced surgeons using an electromagnetic motion-tracking system.MethodsA total of 18 surgeons, who were all right-handed, were divided into the following two groups according to their experience as an operator in laparoscopic surgery: 9 novice surgeons (fewer than 10 laparoscopic procedures) and 9 experienced surgeons (more than 50 laparoscopic procedures). The subjects performed an intracorporeal suturing task in an inanimate box laparoscopic trainer while the movements of their forceps were evaluated using an electromagnetic motion-tracking system. Their laparoscopic skills were assessed on the basis of the time, path length, and average speed of the forceps in each hand.ResultsExperienced surgeons completed the suturing task significantly faster than novice surgeons did. The left path length was significantly shorter for experienced surgeons than for novice surgeons, whereas the right path lengths did not differ. The right average speed of knot tying was significantly faster for experienced surgeons than for novice surgeons, whereas the left average speeds did not differ.ConclusionsEvaluation of psychomotor skills in laparoscopic suturing using an electromagnetic motion-tracking system revealed better results for experienced surgeons than for novice surgeons in terms of the time taken, left path length, and right speed of knot-tying. Furthermore, surgical proficiency due to experience can affect surgical dexterity of each hand differently. The present study also demonstrates the efficacy of this system for objective evaluation of laparoscopic suturing skills.

A remote surgery experiment between Japan and Thailand over Internet using a low latency CODEC system

Remote surgery is one of the most desired applications in the context of recent advanced medical technologies. For a future expansion of remote surgery, it is important to use conventional network infrastructures such as Internet. However, using such conventional network infrastructures, we are confronting time-delay problems of data transmission. In this paper, a remote surgery experiment between Japan and Thailand using a research and development Internet is presented. In the experiment, the image and audio information was transmitted by a newly developed low latency CODEC system to shorten the time-delay. By introducing the low latency CODEC system, the time-delay was shortened compared with the past remote surgery experiments despite the longer distance. We also conducted several network measurements such as a comparison between TCP/IP and UDP/IP about the control signal transmission.

Defective endothelial nitric oxide synthase signaling is mediated by rho‐kinase activation in rats with secondary biliary cirrhosis

In liver cirrhosis, down‐regulation of endothelial nitric oxide synthase (eNOS) has been implicated as a cause of increased intrahepatic resistance. We investigated whether Rho‐kinase activation is one of the molecular mechanisms involved in defective eNOS signaling in secondary biliary cirrhosis. Liver cirrhosis was induced by bile duct ligation (BDL). We measured mean arterial pressure (MAP), portal venous pressure (PVP), and hepatic tissue blood flow (HTBF) during intravenous infusion of saline (control), 0.3, 1, or 2 mg/kg/hour fasudil for 60 minutes. In BDL rats, 1 and 2 mg/kg/hour fasudil significantly reduced PVP by 20% compared with controls but had no effect on HTBF. MAP was significantly reduced in response to 2 mg/kg/hour fasudil. In the livers of BDL rats, 1 and 2 mg/kg/hour fasudil significantly suppressed Rho‐kinase activity and significantly increased eNOS phosphorylation, compared with controls. Fasudil significantly reduced the binding of serine/threonine Akt/PKB (Akt) to Rho‐kinase and increased the binding of Akt to eNOS. These results show in secondary biliary cirrhosis that (1) Rho‐kinase activation with resultant eNOS down‐regulation is substantially involved in the pathogenesis of portal hypertension and (2) Rho‐kinase might interact with Akt and subsequently inhibit the binding of Akt to eNOS. (HEPATOLOGY 2008.)

Interventional navigation for abdominal therapy based on simultaneous use of MRI and ultrasound

An interventional navigation system designed for percutaneous abdominal therapies was proposed, and a pilot study was carried out to assess the proposed system. Integration of US to MRI-based segmentation and 3D display of tumours can help physicians deal with instabilities such as respiratory motion and soft tissue shift that are inherent in abdominal interventions. In addition to the 3D display of the needle and tumours, we adapted the system for the abdominal applications and incorporated a process to correct the mismatch in needle path between MRI and US. The preliminary results of phantom and animal experiments indicated that the proposed method could combine the advantages of both MRI and US. The time required to determine the optimal needle insertion path by using this system was significantly less than that required when either US or MRI guidance alone was employed. The developed system was applied in two patients who underwent PEIT therapy, and its clinical feasibility was partially confirmed.

Skills assessment using a virtual reality simulator, LapSim™, after training to develop fundamental skills for endoscopic surgery

Abstract Education and training to maintain medical safety are very important within clinical settings. We have established a training center for endoscopic surgery and we regularly hold a unique training course, which focuses on the development of fundamental skills. One hundred and ninety-four surgeons who participated in our training course were divided into four groups according to their experience in performing laparoscopic procedures. Group 1: 0–19 laparoscopic procedures (n=44). Group 2: 20–49 laparoscopic procedures (n=53). Group 3: 50–99 laparoscopic procedures (n=46). Group 4: more than 100 laparoscopic procedures (n=55). All subjects underwent evaluation for “Lifting & Grasping” using a virtual reality (VR) simulator, LapSim™, before and after the training course. The mean efficiency score, time to completion and tissue damage after training were significantly improved after the training as compared with before training. Before training, subjects with greater experience had better scores. However, the only significant difference in the score was between the low experience group and greatest experience group. After training, the score increased in all groups compared with that before training, and there was no significant difference between groups. This study demonstrates the feasibility of using a VR simulator to assess fundamental skills for endoscopic surgery after training. We found that the scores for the task were associated with the level of experience of the surgeons.

A surgical robot with vision field control for single port endoscopic surgery.

Robotic end‐effectors for single port endoscopic surgery (SPS) require a manual change of vision field that slows surgery and increases the degrees of freedom (DOFs) of the manipulator.