Takehiro Ando

Precise comparison of protoporphyrin IX fluorescence spectra with pathological results for brain tumor tissue identification.

Photodynamic diagnosis is used during glioma surgery. Although some studies have shown that the spectrum of fluorescence was efficient for precise tumor diagnosis, previous methods to characterize the spectrum have been problematic, which can lead to misdiagnosis. In this paper, we introduce a comparison technique to characterize spectrum from pathology and results of preliminary measurement using human brain tissues. We developed a spectrum scanning system that enables spectra measurement of raw tissues. Because tissue preparations retain the shape of the device holder, spectra can be compared precisely with pathological examination. As a preliminary analysis, we measured 13 sample tissues from five patients with brain tumors. The technique enabled us to measure spectra and compare them with pathological results. Some tissues exhibited a good relationship between spectra and pathological results. Although there were some false positive and false negative cases, false positive tissue had different spectra in which intensity of short-wavelength side was also high. The proposed technique provides an accurate comparison of quantitative fluorescence spectra with pathological results. We found that spectrum analysis may reduce false positive errors. These results will increase the accuracy of tumor tissue identification.

Ultrasound imaging method for internal jugular vein measurement and estimation of circulating blood volume

Purpose Evaluation of circulating blood volume is important in assessing the status of patients. Although some studies have suggested that ultrasound images of the internal jugular vein (IJV) can be used for the analysis of circulating blood volume, accurate extraction of IJV is necessary to reduce errors. Therefore, this study was designed to develop a new algorithm for dynamic segmentation of IJV and determine appropriate indicators to evaluate the circulating blood volume.Methods Our algorithm is based on snake and speckle tracking models. As the region of interest (ROI) of the control points of the snake tracking algorithm was dynamically moved using speckle tracking, ROI size can be decreased leading to a reduction in the tracking error. Some experiments were performed to validate our algorithm. Subsequently, the algorithm was used for the experiment simulating dehydration state among 11 subjects.Results Results of the validation experiment suggest that our algorithm showed higher performance for IJV extraction compared with standard methods. Furthermore, it was revealed that some indices such as the average area of IJV were related to the dehydration state of subjects. Conclusion This study proposed a new algorithm, which was based on snake and speckle tracking models, for dynamic extraction of IJV in ultrasound images. In addition to algorithm validation, it was suggested that some indices the ultrasound image of IJV could be used for the evaluation of the circulating blood volume.

A Novel High Intensity Focused Ultrasound Robotic System for Breast Cancer Treatment

High intensity focused ultrasound (HIFU) is a promising technique for cancer treatment owing to its minimal invasiveness and safety. However, skin burn, long treatment time and incomplete ablation are main shortcomings of this method. This paper presents a novel HIFU robotic system for breast cancer treatment. The robot has 4 rotational degrees of freedom with the workspace located in a water tank for HIFU beam imaging and ablation treatment. The HIFU transducer combined with a diagnostic 2D linear ultrasound probe is mounted on the robot end-effector, which is rotated around the HIFU focus when ablating the tumor. HIFU beams are visualized by the 2D probe using beam imaging. Skin burn can be prevented or alleviated by avoiding long time insonification towards the same skin area. The time cost could be significantly reduced, as there is no need to interrupt the ablation procedure for cooling the skin. In addition, our proposed robot control strategies can avoid incomplete ablation. Experiments were carried out and the results showed the effectiveness of our proposed system.

Automatic laser scanning ablation system for high-precision treatment of brain tumors.

Complete removal of malignant gliomas is important for the prognosis in neurosurgery treatment. Currently, the challenge is how to detect any remaining tumors and resect them during the operation. We have developed a laser ablation system with accurate tumor analysis and fluorescence guidance for high-precision brain tumor resection during neurosurgery. A 5-aminolevulinic acid-induced fluorescent protoporphyrins IX (PpIX)-based intra-operative fluorescence measurement and corresponding spectra analysis technique is used to identify the position of tumors. A galvano mirror scanning mechanism is integrated into the fluorescence measurement and the laser ablation devices for automatic tumor area scanning and corresponding laser ablation. A set of phantom experiments was performed to evaluate the proposed system. Results showed that the galvano scanning mechanism enabled both PpIX fluorescence detection and laser ablation in the same optical axis. In vitro experiments using porcine brain were performed to evaluate the effectiveness of the automatic laser scanning, fluorescence detection, and laser ablation system. The proposed fluorescence-guided laser ablation system can provide accurate analysis and high-precision treatment for tumor resection in neurosurgery. With further improvement, the system can be used in neurosurgical implementation to provide accurate, safe, and simple surgical diagnosis and therapy.

Image mapping of untracked free-hand endoscopic views to an ultrasound image-constructed 3D placenta model

This study presents a tracker‐less image‐mapping framework for surgical navigation motivated by the clinical need for intuitive visual guidance during minimally invasive fetoscopic surgery.

Vision-based endoscope tracking for 3D ultrasound image-guided surgical navigation.

This work introduces a self-contained framework for endoscopic camera tracking by combining 3D ultrasonography with endoscopy. The approach can be readily incorporated into surgical workflows without installing external tracking devices. By fusing the ultrasound-constructed scene geometry with endoscopic vision, this integrated approach addresses issues related to initialization, scale ambiguity, and interest point inadequacy that may be faced by conventional vision-based approaches when applied to fetoscopic procedures. Vision-based pose estimations were demonstrated by phantom and ex vivo monkey placenta imaging. The potential contribution of this method may extend beyond fetoscopic procedures to include general augmented reality applications in minimally invasive procedures.

Prospective analysis of cardiac collapsibility of inferior vena cava using ultrasonography

PURPOSE The inferior vena cava (IVC) diameter and its respiratory change (respiratory variation) reportedly correlate well with the central venous pressure and response to fluid. However, changes in the IVC diameter are related to the cardiac rhythm (cardiac variation), which can be useful as an indicator for intravascular volume but can affect respiratory variation. We conducted a prospective analysis of this cardiac variation in adult emergency department patients. METHODS Ultrasonographic IVC images from 190 consecutive adult emergency department patients were collected prospectively. The IVC diameters 2 cm caudal from the middle hepatic vein were tracked automatically and measured. The IVC diameter changes were analyzed using a software program that tracks 2-dimensional motion in B-mode images. Cardiac and respiratory variations were calculated and analyzed. RESULTS The average IVC cardiac variation was 11.0% (95% confidence interval, 9.8%-12.3%) in these patients, which affects the respiratory variation resulting in 1.68-fold higher overestimation of respiratory variation. The coefficient of correlation between IVC cardiac variations and respiratory variations was 0.34 (P < .05). CONCLUSIONS The IVC cardiac variation affects our interpretation of ultrasonography IVC imaging. The IVC cardiac variation provides several advantages over other parameters of intravascular volume. Therefore, it can be a novel tool to assess the intravascular volume of the patients.

Development of femoral bone fracture model simulating muscular contraction force by pneumatic rubber actuator.

In femoral fracture reduction, orthopedic surgeons must pull distal bone fragments with great traction force and return them to their correct positions, by referring to 2D-fluoroscopic images. Since this method is physically burdensome, the introduction of robotic assistance is desirable. While such robots have been developed, adequate control methods have not yet been established because of the lack of experimental data. It is difficult to obtain accurate data using cadavers or animals because they are different from the living human bodys muscle characteristics and anatomy. Therefore, an experimental model for simulating human femoral characteristics is required. In this research, human muscles are reproduced using a McKibben-type pneumatic rubber actuator (artificial muscle) to develop a model that simulates typical femur muscles using artificial muscles.

Development and fundamental evaluation of flexible viewpoint laparoscope using a oblique viewing laparoscope

We have developed a new type of laparoscope with flexible view point. This system can move the view without moving laparoscope itself. To achieve the wide range of view moving, we used a commercial 30° oblique-viewing laparoscope and special lens. The system control the view by rotating the oblique-viewing laparoscope and a sleeve which is attached to the special lens by motors independently. From the evaluation experiments, we confirmed the laparoscope which has 70° view angle could move the view ±60°. In the image quality evaluation experiment, degradation of the image quality was small. The positioning accuracy was 2.4±1.7mm repeatability was 0.48mm which lead to precise view control. The system achieve the safe and smooth manipulation of the laparoscopic view.

Towards scene adaptive image correspondence for placental vasculature mosaic in computer assisted fetoscopic procedures.

Visualization of the vast placental vasculature is crucial in fetoscopic laser photocoagulation for twin‐to‐twin transfusion syndrome treatment. However, vasculature mosaic is challenging due to the fluctuating imaging conditions during fetoscopic surgery.