Biomedical subjects

Naoki Suzuki

Publications and source records attributed to Naoki Suzuki.

At least 19 recordsLinked to original sources

PubMed2006

Robotic surgery setup simulation with the integration of inverse-kinematics computation and medical imaging.

At present, there are representative robot operation systems such as da Vinci and ZEUS which have realized minimally invasive surgery by the use of dexterous manipulators. In the operating room, medical staff must prepare and set up an environment in which the robot has optimal freedom of motion and its functions can be fully demonstrated for every case. The range of motion in which the robot can reach and be maneuvered is restricted by the fixed point of the trocar site. We have developed a preoperative planning system with the function of volume rendering of medical images and automatic positioning by applying an inverse-kinematics computation of surgical robot. The motion of a surgical robot can be simulated in advance with the intuitive interface and kinematics computation program running in the background of the system. If robotic surgery planning with volume rendering of DICOM images is possible, the discussion of a surgical plan can be directly made just after the diagnosis considering the patient-specific structure. This kind of setup platform would be essential for the future introduction of surgical robotics into an operating room.

Algorithms↗

PubMed2006

Laser-scan endoscope system for intraoperative geometry acquisition and surgical robot safety management.

In laparoscopic surgery, surgeons find particular difficulties related to the operation technique. Due to restricted view, lack of depth information from the monocular endoscope and limited degree of freedom, surgeons find their movements impeded. A support system that provides improved laparoscopic vision would help to overcome the difficulties. If real-time visualization of abdominal structures were feasible, more accurate procedures and improved quantitative evaluations in laparoscopic surgery might be possible. In this study, a laser-scan endoscope system was developed to acquire and visualize the shape and texture of the area of interest instantaneously. The intraoperative geometric information of deformable organ could be applied for robotic safety management via geometric computation of robot position and organ shape. Results of in vivo experiments on a pig liver verified effectiveness of the proposed system.

Animals↗

PubMed2006

Synthesis and optical property of beta-brass colloid.

Cu/Zn beta-phase alloy (beta-brass) colloid was successfully synthesized by reducing the organometallic complexes in the organic liquid phase. It was confirmed by X-ray diffraction that the material formed pure beta-phase. The morphology for the beta-brass particles was observed using transmission electron microscopy (TEM). The dispersion of the particle diameter was almost single modal, and the diameter was estimated at 8+/-2 nm. A clear peak around 520 nm was seen in the optical absorption spectrum for the beta-brass colloid, and it is attributed to the surface plasmon absorption. We also simulated the optical absorption spectrum using the bulk dielectric constant for beta-brass. The simulation qualitatively reproduced the experimental data well.

Journal Article↗

PubMed2006

The effects of atorvastatin on coronary endothelial function in patients with recent myocardial infarction.

BACKGROUND: Endothelial dysfunction is a key early event in atherosclerosis that occurs in acute coronary syndrome. It was reported that atorvastatin improves the endothelial function of skeletal muscle vessels, but the effect on the coronary artery is unknown. HYPOTHESIS: The purpose of this study is to determine the effects of atorvastatin on coronary endothelial function in humans. METHODS: Non-infarct-related coronary arteries of 48 patients with acute myocardial infarction who had undergone successful percutaneous transluminal coronary angioplasty were examined. Three groups were studied: hyperlipidemia with use of atorvastatin (Group 1, n=17), hyperlipidemia without statin use (Group 2, n=18), and normal cholesterol level controls (Group 3, n=13). Statin treatment was started at discharge. Acetylcholine (Ach) was infused into the coronary artery and the diameter was assessed by quantitative angiography at baseline and after 6 months. RESULTS: Acetylcholine given in doses of 1, 3, 10, and 30 mg/min increased the coronary artery diameter change in a dose-dependent manner. In the initial study, patients in the three groups had similar responses to Ach. The mean diameter change after 6 months was significantly improved in Group 1 compared with Groups 2 and 3 (-11 +/- 3% vs. -20 +/- 7% and -21 +/- 6%, respectively; p < 0.01 in each case). Multivariate regression analysis showed that atorvastatin (p < 0.01) was the significant determinant for improvement of endothelial function. CONCLUSIONS: These findings suggest that atorvastatin improves endothelial function of the coronary artery in patients with myocardial infarction.

Acetylcholine↗

PubMed2006

Surgical navigation display system using volume rendering of intraoperatively scanned CT images.

As operative procedures become more complicated, simply increasing the number of devices will not facilitate such operations. It is necessary to consider the ergonomics of the operating environment, especially with regard to the provision of navigation data, the prevention of technical difficulties, and the comfort of the operating room staff. We have designed and created a data-fusion interface that enables volumetric Maximum Intensity Projection (MIP) image navigation using intra-operative mobile 3D-CT data in the OR. The 3D volumetric data reflecting a patient's inner structure is directly displayed on the monitor through video images of the surgical field using a 3D optical tracking system, a ceiling-mounted articulating monitor, and a small-size video camera mounted at the back of the monitor. The system performance and accuracy was validated experimentally. This system provides a novel interface for a surgeon with volume rendering of intra-operatively scanned CT images, as opposed to preoperative images.

Computer Graphics↗

PubMed2006

Soft-tissue balance evaluation system for total hip arthroplasty by intraoperative contact pressure measurement at the hip joint.

We developed a system for measurement of contact pressure at the hip joint surfaces that enables checking of the artificial hip joint condition during surgery. First, we constructed the pressure sensor that forms the artificial joint. We installed eight small pressure sensors to the spherical head component, a part of the ball-socket joint. Next, we developed software for recording and visualizing the detected pressures that were recorded every 1 ms. The pressure distribution was displayed with the 3D computer graphics in real-time. The system enabled intuitive recognition of pressure direction 3-dimensions. Next, using the system, we conducted measurements during total hip arthroplasty. Although it requires some improvements in its measurement accuracy, the system allows real-time acquisition of information on the artificial hip joint in real-time. Further improvements of the calibration method should enable more accurate measurements. As a complete system, it will be a useful tool for selecting an appropriate implant that fits a patient's hip joint or for estimating the risk of complications after surgery.

Arthroplasty, Replacement, Hip↗

PubMed2006

Estimation of skeletal movement of human locomotion from body surface shapes using dynamic spatial video camera (DSVC) and 4D human model.

We have been developing a DSVC (Dynamic Spatial Video Camera) system to measure and observe human locomotion quantitatively and freely. A 4D (four-dimensional) human model with detailed skeletal structure, joint, muscle, and motor functionality has been built. The purpose of our research was to estimate skeletal movements from body surface shapes using DSVC and the 4D human model. For this purpose, we constructed a body surface model of a subject and resized the standard 4D human model to match with geometrical features of the subject's body surface model. Software that integrates the DSVC system and the 4D human model, and allows dynamic skeletal state analysis from body surface movement data was also developed. We practically applied the developed system in dynamic skeletal state analysis of a lower limb in motion and were able to visualize the motion using geometrically resized standard 4D human model.

Biomechanical Phenomena↗

PubMed2005

Late-onset distal myopathy with rimmed vacuoles without mutation in the GNE or dysferlin genes.

We report two brothers from a Japanese family with a late-onset distal myopathy characterized by rimmed vacuoles and dysferlin deficiency with no inflammatory infiltration and dystrophic changes in muscle biopsy. Mutations in the GNE, dysferlin, caveolin 3, emerin, and lamin A/C genes were excluded. We speculate that dysferlin is involved in the pathogenesis of the myopathy in these patients, which may represent a new disease entity presenting as a distal myopathy.

Adult↗

PubMed2005

Data-fusion display system with volume rendering of intraoperatively scanned CT images.

In this study we have designed and created a data-fusion display that has enabled volumetric MIP image navigation using intraoperative C-arm CT data in the operating room. The 3D volumetric data reflecting a patient's inner structure is directly displayed on the monitor through video images of the surgical field using a 3D optical tracking system, a ceiling-mounted articulating monitor, and a small size video camera mounted at the back of the monitor. The system performance was validated in an experiment carried out in the operating room.

Computer Graphics↗

PubMed2005

Ultrasonic tissue characterization predicts left ventricular remodeling in patients with acute anterior myocardial infarction after primary coronary angioplasty.

OBJECTIVES: The aim of this study was to assess the role of cyclic variation (CV) of myocardial integrated backscatter (IBS) in the prediction of left ventricular (LV) remodeling in patients with anterior acute myocardial infarction (AMI) after primary coronary angioplasty. BACKGROUND: Some studies have shown that the CV of myocardial IBS predicts myocardial viability for patients with AMI. METHODS: We recorded short-axis IBS images within 24 hours of angioplasty in 80 patients with anterior AMI. Two parameters were measured: the magnitude of CV and the normalized time delay (NTD). The increase in LV end-diastolic volume (LVEDV) at 4 weeks (DeltaLVEDV) was defined as LV remodeling (>20% increase from baseline). RESULTS: Patients were divided into two groups according to LV remodeling status: the remodeling group (n = 41) and the nonremodeling group (n = 39). There was a significant difference in the magnitude of CV between the two groups (5.11 +/- 1.47 vs 5.96 +/- 189 dB, P < .05), and the NTD was significantly different in the two groups (1.57 +/- 0.31 vs 1.23 +/- 0.32, P < .0001). The correlation between the magnitude of CV and DeltaLVEDV was significant but weak (r = -0.338, P < .01). There was significant correlation between NTD and DeltaLVEDV (r = 0.443, P < .0001). Using NTD greater than 1.35 as the optimal cutoff, the sensitivity, specificity, and positive and negative predictive values to predict LV remodeling were 82%, 86%, 87%, and 80%, respectively. CONCLUSIONS: Myocardial IBS, especially NTD, is useful for predicting LV remodeling in patients with AMI after primary coronary angioplasty.

Angioplasty, Balloon, Coronary↗

PubMed2005

Gait analysis system for assessment of dynamic loading axis of the knee.

The purpose of this study was (1) to demonstrate a computer-assisted gait analysis system that can visualize the locus of the dynamic loading axis on the proximal tibia joint surface, and (2) to assess the accuracy of this system in a patient with bilateral knee osteoarthritis (OA). This system uses force plate data, CT skeletal structure data and motion capture data obtained from an infrared position sensor. The relative positions between bones and markers were used to calculate skeletal model movement based on movement of the markers. The locus of the dynamic loading axis on the knee joint was defined as the point on the proximal tibia joint surface that intersected with the loading axis of the lower limb, which passed through the centre of the femoral head and the centroid of multiple points surrounded by the distal tibia joint surface contour. To assess the accuracy of this system, open MRI was used to evaluate positions of skin markers against bones in six healthy volunteers. The locus in a patient was affected by differences between the varus knee with medial compartment OA on the non-operative side and the knee treated with high tibial osteotomy (HTO) on the opposite side. At knee flexion angles of 0 degrees, 15 degrees and 30 degrees, the mean value of measurement error for point locations on the locus was within 5.6% of joint width in the lateral direction (JWLD) on the proximal tibia joint. This system can provide clinically useful information for evaluation of the dynamic loading axis on the knee joint surface.

Aged↗

PubMed2005

Change in the locus of dynamic loading axis on the knee joint after high tibial osteotomy.

The purpose of this study was to visualise the locus of the dynamic loading axis on the knee joint, and to evaluate changes in this locus during gait after high tibial osteotomy (HTO) in three patients who underwent HTO for medial compartment osteoarthritis (OA) of a varus knee. The bone structure of the lower limb and the relative position of skin markers were acquired from CT images. Motion capture data was acquired using spherical skin markers. Skeletal model movement during gait was calculated based on the movement of the markers. The locus of the dynamic loading axis on the knee joint was defined as the point on the proximal tibia joint surface that intersected with the loading axis of the lower limb, which passed through the centre of the femoral head and the centroid of multiple points surrounded by the distal tibia joint surface contour. This system was able to visualise the locus of the dynamic loading axis on the knee joint and not only lateral but also anterior-posterior direction movement. After HTO, the locus shifted from a medial and posterior area of the medial joint edge of the knee to a central area of the knee joint surface. This indicates that HTO shifted the dynamic loading axis. Lateral movement of the dynamic loading axis in the early stance phase of gait was reduced within a year after HTO.

Aged↗

PubMed2005

Expression profiling with progression of dystrophic change in dysferlin-deficient mice (SJL).

The SJL mouse is a model for human dysferlinopathy (limb-girdle muscular dystrophy type 2B and Miyoshi myopathy). We used cDNA microarrays to compare the expression profiles of 10,012 genes in control and SJL quadriceps femoris muscles in order to find genes involved in the degeneration and regeneration process and in dysferlin's functional network. Many genes involved in the process of muscle regeneration are observed to be up-regulated in SJL mice, including cardiac ankyrin repeated protein (CARP), Neuraminidase 2, interleukin-6, insulin-like growth factor-2 and osteopontin. We found the upregulation of S100 calcium binding proteins, neural precursor cell expressed, developmentally down-regulated gene 4-like (NEDD4L) with C2 domain, and intracellular protein traffic associated proteins (Rab6 and Rab2). These proteins have the potential to interact with dysferlin. We must reveal some other molecules which may work with dysferlin in order to clarify the pathological network of dysferlinopathy. This process may lead to future improvements in the therapy for human dysferlinopathy.

Animals↗

PubMed2005

Left ventricular free wall rupture in transient left ventricular apical ballooning.

A 79-year-old woman presented with chest pain. Her symptoms, combined with the results of an electrocardiogram, echocardiogram and laboratory investigations were compatible with an extensive acute anterior myocardial infarction. However, emergency coronary angiography showed no stenotic lesion in any coronary artery, but left ventriculography revealed apical ballooning akinesis and basal hyperkinesis and she was diagnosed as having transient left ventricular apical ballooning. After 7 days, she suddenly went into cardiopulmonary arrest because of cardiac tamponade. The autopsy revealed a free wall rupture. Generally, the prognosis in transient left ventricular apical ballooning is good; left ventricular free wall rupture is very rare.

Aged↗

PubMed2005

Impact of hydroxymethylglutaryl coenzyme A reductase inhibition on left ventricular remodeling in patients with acute anterior myocardial infarction after primary coronary angioplasty.

Hydroxymethyglutaryl coenzyme A reductase inhibition (statin) therapy has been shown to reduce cardiac hypertrophy in vitro and in vivo. We assessed the influence of short-term statin therapy on left ventricular (LV) remodeling after acute myocardial in-farction. Thirty-five patients with first anterior acute myocardial infarction, who underwent primary coronary angioplasty within 12 hours of onset, were divided into 2 groups. Ten patients taking statin served as the statin group, and 25 patients not taking statin served as the control group. Two-dimensional echocardiography was recorded after angioplasty (baseline) and at 4 weeks. LV ejection fraction (LVEF) at baseline was not significantly different between the 2 groups. However, the statin group had a higher LVEF at 4 weeks than the control group (58.2 +/- 5.0 versus 49.0 +/- 12.7%; P < 0.05). Moreover, the increase in LV end-diastolic volume (LVEDV) at 4 weeks was lower in the statin group than in the control group (12.1 +/- 29.6 versus 39.9 +/- 35.7 mL; P < 0.05). Multiple regression analysis demonstrated that administration of statin was an independent factor for the increase in LVEDV (P < 0.05). These findings indicate that short-term statin therapy can prevent postinfarct LV remodeling and improve LV function.

Aged↗

PubMed2005

Surgical robot setup simulation with consistent kinematics and haptics for abdominal surgery.

Preoperative simulation and planning of surgical robot setup should accompany advanced robotic surgery if their advantages are to be further pursued. Feedback from the planning system will plays an essential role in computer-aided robotic surgery in addition to preoperative detailed geometric information from patient CT/MRI images. Surgical robot setup simulation systems for appropriate trocar site placement have been developed especially for abdominal surgery. The motion of the surgical robot can be simulated and rehearsed with kinematic constraints at the trocar site, and the inverse-kinematics of the robot. Results from simulation using clinical patient data verify the effectiveness of the proposed system.

Biomechanical Phenomena↗

PubMed2005

Development of a navigation function for an endosocopic robot surgery system.

An endoscopic robot system that we reported at MMVR11 is able to perform various surgical procedures in the stomach by using two manipulators. However, it is difficult for surgeons to recognize the 3D location and the direction of the endoscope's tip in the abdominal region during robotic surgery. In this research, we have developed a navigation function that enables image-guided surgery by superimposing the patient's abdominal organ structure onto the endoscopic image. In this paper, we describe the overview of the navigation for the robot system and the result of an animal experiment done while applying the system.

Endoscopy↗

PubMed2005

Development of a 3D visualization system for surgical field deformation with geometric pattern projection.

Intra-operative navigation in which the target position is provided to assist an intuitive understanding of the surgical field has been studied and applied in many clinical areas. Position measurement of a surgical field is usually performed with a magnetic sensor, a marker type optical position sensor. For navigation of hard tissue, the measurement of several markers dispersedly located on the surface is enough to detect the position of an object that can be assumed as a rigid body. However, for the navigation of soft tissue such as skin and liver, a sensor that can measure the deformation of the object surface time-sequentially would be essential. We have developed a 3D visualization system for surgical field deformation with geometric pattern projection. In an animal experiment, the registration of preoperative 3D organ model could be done with the time-sequentially updated surface deformation data. In the video image of surgical field, the inner structure model of organ could be superimposed successfully.

Elasticity↗