Journal of Computer Aided Surgery Vol.4 No.3-2
Abstract：In this paper，we describe a method for generating virtual laparoscopic
images based on deformation of 3－D abdominal CT images．Laparoscopic surgery
is now widely performed as one of less invasive surgical procedures．The
field of view of laparoscope is very limited．If we could virtually generate
laparoscopic images from CT or MR images Taken before the surgery，these
images would be useful as reference or guidance images of the surgery．During
laparoscopic surgery procedure，abdominal wall are lifted up for creating
working space by the air．This paper generates virtual laparoscopic images
based on deformation ofthe pre－operative CT images．Abdominal wall of
the original CT image is virtually lifted by direct de forma－tion of the
image．We applied the method to a real abdominal CT image and connrmed
that the method could generate virtual laparoscopic images satisfactorily．
Keywords：virtual lapaloscopic image，virtual endoscope system，laparoscopic surgery，surgical simulation
○生田幸士 福山純也 笹子宏史（名古屋大学 工)
Abstract：The new force calibration system was developed by building in the small sensing system.This system enabled the exact force display using actual endoscope which outer diameter and surfacestate differ．Furthermore，it succeeded in modifi－cation of complicated large intestine form and exact calculation of reaction，developing the high precision large intestine model which improved the dynamics characteristic and calculation algorithm radically，andmaintaining real－time nature.
Key Words:Vitual Reality，Endoscope，Force Sensation，Virtual Endoscope System，Force caribration
1．Introduction．
We will present robotic microsurgery system based on master-slave arm method and it will contribute to the field which requiremicrosurgical technique such as hand，plastic and reconstructivesurgery.
2．Materials and Methods
The manipulator has a seven axis and moves according to the command from master arm We selected AC servo motor as an actuator and a harmomic drive as a reducer.High resolution optical encoder is selected for transmitting the command from master arm to the slave arm
We used the silastic vessel as materials and evaluated following points．1）Wbrking area（10x10x10cm），2）Hold and change the direction of micro vessel and nerve 3）Dilate the vessel 4）Release the vessel from soft tissue 5）Cut the vessel 6）Make a small hole on the vessel 7）Insert the 9-0 and 10-0 nylon into the vessel 8）Assist surgeon during making suture on the vessel and nerve．
3．Results and Discussion
Based on advanced motor technology，precise movement of mamipulator tip was possible．
In the experiments，it was comfortable to mamipulate the system．In the next step we will try to make the system smaller to match the real operating field for climical use．We believe that this study will lead to more advanced computer assisted mamipulator system for microsurgery
Keywords：microsurgery,manipulator，operation
Abstract－We developed a new medical operation procedure and robotic tool of microsurgery in deep and narrow site.
It enables us to operate a difncult microsurgery that conventionalmethod
can't be achieved.Our system consists of fiexible slave micro manipulators
which can enter deep site of human body like a flexible catheter and master
manipulators.Owing to difference of their sizes，it enables to convert
micromotion of slave into natural size motion of master. Finally，both
feasibility and effectiveness of the total system were verified experimentally.
KeyWords：Remote Microsurgery System，Medical robotics，Minimally invasive surgery，Master－Slave
Abstract：A motion study of the manipulation of catheter in angiography
was performed in this study for the development of catheter manipulator
in angiography．The average velocity of the catheterinsertion was 6．1cm／sec．and
the velocity at the search for vascular branch was 2．5cm／sec．
3.9 times of manipulation were needed for the selective catheterizaion
into the branch of the aorta．on the average.The velocity of tilting was
about 180°／sec. Further data about the tactile sense should be investlgated
for the design of catheter manipulator in angiography．
KeyWords：angiograpy，motion study，catheter－manipulator
Abstract：We have developed the micro－manipulator system for neurosurgery．This
system is the surgery support system for minimally invasive neurosurgery.We
examined simulation of surgery withthis system for the cadaver.In the deep
brain the manipulator system had been operated well．Then functions of
circulation and suction had been confirmed．Surgeons evaluated that the
functionof this system for neurosurgery are valid．
Keywords：surgery support system，minimally invasive neurosurgery，micromanipulator
Abstract：We developed a compact robot for manipulating forceps using a friction wheel and gimbals mechanism．This forceps manipulator works as a small slave robot in master－slave robotic system.Friction wheel mechanism realized the rotation and translation（back and forth）of forceps．It has merits in small size，no limitation to the moving rage，and adaptation for various forceps．Gimbals mechanism determines the inserting direction of the forceps.The rolling motion of the gimbals mechanism was drivenwith the linkage mechanism.
This enabled the separation of the motors from the sterilized part.This manipulator is enough small to use three sets without occupying the operating space above the abdomen．
KeyWords：Medical Robot，Minimally invasive surgery，Forceps manipulator，
Abstract
During recent years，various navigation systems become available in brain
surgery．However；these systems cannot display the information display
into operative field．This disadvantage can overcome by AR image overlay
system（ARIOS），which is constituted by the acrylics board with the function
of a one－way mirror and flat LCD display The system is fixing to the
operating table by multi－flexible fixation．3D picture is created using
MRI data．This image is renected on the operative field using a one－way
mirror．Therefore，complex relationships between tumorand different cerebral
structures can be visualized by ARIOS directly in the surgical field．
［Keywords］Augmented reality，navigation，half mirror
Abstract：This paper proposes a high-resolution autdereoscopic surgical
display system using the paralle-calculation”Integral Videography”（ⅠⅤ）and
multi-projection technique．Ⅳcan display geometrically accurate autostereoscqpic
images and reproduce motion parallax in three-dimensional （3-D）space
without using special viewing glasses．We obtain precise aligrment infonnationwith
a digital camera by measuring the position and color features of projected
image on the screen via micro convex lens array，and then feedback the
calibrahon information to the image-processing hardware to make fine adjusuments．We
evalutaluate feaasibility of this display by develqping a 3－D CT image
and applying it to surgical planning and intra-operative guidance．The
maincontribution of this paper is application and modification of medical
3-D image visualization technique originally developed in high－resolution
multi-projector autostereoscopic display system．
KeyWords：integral videography，multi－prqjection，autostereoscipic，image processing
Abstract－The stereoscopic pictures obtained from Magnetic Resonance Image（MRI），X－ray Computed Tomography（CT），etc are used for an operation－supporting picture，and operations under picture guidance has been also conducted．One of the stereoscopic methods is integral videography（IV），we have developed based on integral photogrphy，projecting a computer－generated graphical object．Though the advantage of IV has been proven in bothfeasibility studies and clinical applications，one of the issues still unsolved is notable quantlty of calculation that causes significant delay in rendering．Then using parallel processing method integrating Message Passing Interface（MPI）on High Performance Computer（HPC），we shortened the calculating tlme of IV picture by the shortest at about 0．2 seconds．Furthermore by using sokcket communication it transmitted to another portable note PC，which is for a display．Then，we achieved the fast presentatin of stereoscopic tures seen from arbitrary direction that was specified with the mouse from the note PC side at anywhere we can access to the network．
KeyWords：MPI，Integral Photography Integral Videography,Parallel Rendering，Ultrasonic
Abstract: Many types of medical images are used for neurosurgicalnavigation
system，however，surgeon often encounters the difnculties to have a precise
registration between pre－（or intra－）operative images and the patients.To
solve this problem，we are developing an augmented reality system with
a simple display device．The display device comprises a 6 inch LCD flat
panel display,plastic panel as a half-mirror and a passive positioning
marker to detect the spatial position in the operating room．Through the
half mirror，surgeon can observe the real patient and the reflected image
of the display；on which the navigation image are described simultaneously．By
the navigation system，the display image is shown in an appropnate position
and the exact size in side the patient．The display is moved back and forth
to change the depth．Phantomtests are performed using a honeydew melon
and the volunteer．Weobserved the basic functions working correctly．This
device willbe useful using intra－operative images such as interventional
MRI．
Keysords：surgical navigation，augmented reality；half mirror
Abstract：We developed a laser guidance system to present the information of navigation directly in the surgical field．In this system，an intersection line of laser beam planes emitted fromtwo or more laser pointer devices fits on the line determined bythe target point and the desired direction of a surgical tool such as a drill or a wire．A surgeon puts the tip of the tool on the cross point of laser lines drawn the surface of the targetedpart，and adapts the laser line drawn on the side of the tool parallel to the axis of the tool．As a result of the accuracy evaluation experiment，position error at the target－point and direction error of the tool were within±1．0 mm and±1．0deg．In ourclimical experience，our laser guidance system has worked well in the operating room．
Keyword：Information presentation，Navigationsystem，Laser beam，Surgical tool guidance
Abstract
We are developping a surgical navigation system for spinal alignment correction．In previous surgical procedures，pre－and post－operative spinal alignments were measured in the X－ray（2D） image，and mapping of the alignment plan in to physical space was not completely quantitative．Therefore，we aim to achive the surgical navigation which has the feedback routine of spinal alignment data of 3－D．For this purpose，a pre－operative measurement system of spinal alignment by using conventional X－ray imaging system and a surgical navigation system for alignment correction have been developed．
Keywords：surgical navigation system，spinal alignment correction，2－D／3－D registration，reliability computation
Abstract:As increasing Minimally Invasive Surgery,many resear her（developed surgical navigation systems.
These systems often visualize images that could not see derectly,by superimposing images from MRI,CT,etc.to real patient's image.Such systems support the operator to know the relationship between the target area and the other vital area in the patient's body.However, they do not support the task itself because they only visualize the data.In this paper,we propose force navigation system,which generates appropriate force between the tool that the operator holds and the target area of the patient's body to navigate the tool.By using force sensation system could navigate the tool and support operator's task derectly.Furthermore,we describe about the algorithms for generating approoriate force and about the experiment using phantoms for pituitary adenoma.
Keyword:force navigation,haptic,augmented reality,supporting system
Abstract：We have developed the navigation system for laparoscopic surgery so far.This system measures the 3D position at the tip of ultrasound probe inside the body using magnetic 3D position tracker．Although magnetic trackers seem to be particularly suitablefor this purpose,their accuracy is affected by metallic objects such as operating equipment which distort the magnetic field．Inthe past decade，researchers have proposed a number of methods to improve error correction of magnetic 3D tracker which needs alot of time in advance．We propose realtime distortion correction of magnetic fields which does not need pre－preparation using a magneto－optic hybrid 3D position tracker，aim to aquire the accurate three dimensional ultrasound image．As a result，we confirmed the efficiency of the navigation system to experiment in the environment supposing to actual surgery with peripheral metallic objects．
Keywords：real－time distortion correction，hybrid 3D positiontracker，polynomialfit，3D ultrasound
Abstract：We have aimed to develop a augmented reality navigation system for laparoscopic surgery．In laparo－scopic surgery，aoblique laparoscope is commonly used to extend the field of view．Several augmented reality navigation system for endoscope surgery were proposed，but its projection model has not been proposed．We have recently proposed a projection model of a obliqlle laparoscope andits calibration method in the previous work．In this paper，we developed a augmented reality navigation system compatible with a oblique laparoscope．
Keywords：augmented reality，oblique laparoscope，camera model，surgical navigation system
Abstruct：We applied a data fusion system to robotics surgery system“da Vinci”．The system projects 3D reconstructed models of patient's organs in the laparoscope's surgical field and enable to observe the internal structure of the organs in real－time．In order to superimpose 3D reconstructed images of the organs to laparoscope's view，we used digital video processing system and optical location sensor for tracking laparoscope's location．Using this system，the surgeon was able to observe inner conditions of organs with stertoscopic view．
Keywords：data fusion，robotics surgery，navigation system
Abstract：We developed an endoscopic robot system which possess two manipulators for various kind of surgical works in the gastric tubes．Distal part of manipulator functions as forceps and they are able to hold and handle soft tissues as a cooperative works of right and left arms．And it is also able to incise the gastric wall by holding electrical scalpel（taken out from the instrument channel）with the manipulator on the right side while opening the sectioning plane on the left side which was take out．With this system we succeeded the mucosal resection of the stomach wall with large size in case of animal experiment with pigs．It is said，the new approach of robotic surgery in the gastric tube without penetrating the body surface with this kind of surgical robot．
Keywords：Endoscopic Robot，Endoscopic Mucosal Resection（EMR）
Abstract：The main trend of surgery has changed from "Iinvasive surgery"to
"minimally invasive surgery"．The newly developed computer enhanced
surgical system"da Vinci"has been used to performcardiac operations，digestive
surgery and gynecological operations，and it has shown an excellent capability
for performing operations．We herein report the Nissen fundoplication for
reflux esophagitis in laparoscopic surgery assisted by the"da Vinci"surgical
system．3－D view provided a better understanding of the patient's anatomy，gave
us a more detailed orientation regarding the macroscopic view during the
operation．The"da Vinci"arms had an excellent movement capability，which
was closely similar to that of the human wrist，and this greatly helped
surgeons to perform various operative procedures，such as needle puncture，suture
and ligation without either physiologlcal trembling or accidental puncturing．Our
findings suggest that this new computer enhanced surgical system，"da
Vinci"，offer great promise as a modality to perform Nissen fundoplication
for reflux esophagitis in laparoscopic surgery．
Keywords：renflux esophagitis，Nissen fundoplication，computer enhanced surgical system，da Vinci
Abstract：A remote－controlled endoscope positioning system，Naviot（Hitachi Ltd．），was newly developed and applied to a laparoscopic splenectomy on 5 patients with liver cirrhosis．The system consists of a five－bar linkage mechanism，an automatic zoom，and a controller．The mechanism and the automatic zoom are ga sterilizable．A surgeon could easily control the zoom and the 8 directions of the laparoscopic movement．The moving range was about 45 degrees on vertical and about 25 degrees on horizontal directions.It was not necessary to export the endoscope from abdominal cavity during the operation to clean the lens.All procedures were performed safely and smoothly．The new system replaces the surgeon who holds the camera，and provides“solo surgery”．
Keywords：Remote－controlled endoscope positioning system，Laparoscopic splenectomy，Solo surgery
Abstract：We have developed a multi－DOF brain retract manipulatorfor minimally invasive neurosurgery．
We believe that we could extend the range of the robotic minimallyinvasive neurosurgery by developing our system that assures surgical manipulator system a suitable saftty In this report，we developed a total model aimed at clinical application．We newly developeda polyarticular spatula thickness of 2 mm，its tension sensing system from the result of animal experiment and a 6－DOF supporting structure suppoorts the brain retract manipulator．
Keywords：Minimally invasive surgery，Brain retraction，Manipulator
Abstract：Recently，intra－operative magnetic resonance imaging（IO－MRI）has
become an important clinical procedure.To performthis work，MR－compatible
surgical equlpment is necessary.In this study，our research team developed
the technology for a MR－COmpatible manipulator for minimally invasive
liver surgery that can operate in an MRI－scanner without any significant
influenceon MR imaging．The developed system that allows for 6 Degrees
of Freedom (D.O.F）and a new RCM mechanism and bending forceps actuated
by a motor－hydraulic actuation system.This manipulator provides enough
power for liver surgery and is small enough to be operated with in 45 cm－high
space in an Open－MRI.The image distortion withinthe MRI is minimal considering
the effect of materials used in the system.These results demonstrate that
it is feasible to operate the manipulator during MR operation and scanning．
Keywords：MR-compatibility，Interventional MRI，Medical manipulator，Minimally Invasive
Abstract-This paper proposes a new endoscopic forceps manipulator using
2 bending mechanisms by multi－slider linkage mechanism to achieve high
mechanical performance and applicability．A bend－ing mechanism consists
of 3 outer frames，2 rotating joints and 2 sliding linkages for drive and
restraint．2 pin－joints can rotate ±45 degrees respectively，enabling
rotation of ±90 degrees.The rotation of the joint is available by pulling／pushing
the adjacent element by sliding linkage in order.We combined 2 bending
mechanisms，one is for horizontal bending and the other is for vertical
bending，enabling 2－DOF independent motions between－90 degrees and＋90
degrees．The 2－DOF bending mechanism and 1－DOF grasping mechanism are
driven by 3 brushless DC－servomotors．A personal computer－based control－unitdetermines
displacement of sliding 2linkages and pulling 1wire for grasping mechanism．We
examined the bending angle against the target angle．Averagesstandard deviation
of 5 measure－ments were 0.87 degrees in horizontal bending and 0．91degrees
in vertical bending．In conclusion，we are sure of high reproducibility，large
working space andsmall hysteresis of this bending mechanism．
KeyWouds：Multi－slider linkage，Endoscopic，Manipulator
Abstract：Recently，remote control laparoscopic surgical robots have been used in order to perform Mini－mally Invasive Surgery and some of them are already available on the market．However，it is necessary to develop a smaller－sized and flexible robotto perform a less invasive surgery．And one of the promising ap－plications of such robots is the Endoscopic Mucosal Resection（EMR）used in the treatment of early gastro－intestinal cancers．To perform the EMR using an endoscopic surgery robot the surgeon has to teleoperate the slave robot that resides inside the patient body via a master device．In this case，it is necessary toscale down the human movepents and scale up the contact forces to achieve a high maneuverability.However，when the manipulated environment is such small it is necessary to consider the scaling effects due to the high viscosity and friction of the environment．The aim of this work is to develop an Endoscopic Master－Slave System to conduct microsurgery and determine the qppropriatescaling parameters according to the proposed evaluation method．To determine the control and mechanical system's specincations some basic experiments were realized in－vivo with an anesthetized pig．
Keywords：Endoscopic Master－Slave Robot，Endoscopic Mucosal Resection（EMR），Scaling Effect．
Abstract：In this study we have developed the less invasive osteotomy device by an ultrasonic surgery apparatus to enhance theskill of the operator．Now smooth osteotomy requires considerable experience and skilled technique．To do osteotomy more simply and less invasive，we proposed as mechanical device to manipulate an ultrasonic surgery apparatus．To cut a bone without heat denaturation，we evaluated influence of feed speed and applied force on heat denaturation．The result showed that the reaction force gave an indication of cut－through temperature and the conditions for cutting without heat denaturation were feed speed below0．1mm／s and applied force below 250gf.
Key Words：Less invasive osteotomy，Ultrasonic surgery apparatus，Denaturation
Abstract：The aim of this study is measurement of the force and torque during needling the vertebra for the design of the robot that image－guidedly needles the vertebra．They were measured during needling of the formalin-fixed cadaveric vertebra（FF－V）and the poly－urethane phantom in the condition of a couple of sets of the advancing and rotating speeds with a needling apparatus．Results indicated that the force and torque during needling FF－V are 0．53－2．71 kgf and1．74－3．70 kgf－cm，respectively，and that they are decreased with lower advancing speed and higher rotating speed，respectively．
Keywords：percutaneous vertebroplasty，needling force and torque．
Abstract：We developed a minimally invasive device to harvest human bone marrow cell for the bone marrow transplantation（BMT） using the Perfusion Method．We applied the perfusion method，newly proposed bone marrow harvesting method，to our device.Bone marrow cells in the iliac bone are perfused with physiologcal saline under the constant pressure controlled by an actuator.The proposed device can harvest bone marrow from donors' iliac bone with minimal puncture.Additionally，the time needed to carry out BMC harvesting and contamination of T cells can be minimized.In this paper，we developed a prototype of the device and assessed the mechanical performance of it.The device was equipped with a DCservomotor and a pressure sensor.Negative pressure was controlled by feed back of the measured pressure value.The flow of physiological saline was measured by the rotational speed of the motorand limited ad efault value．We found that the device can perfuse the phantom of the bone marrow under constant pressure，which have a margin of error of 1．8 KPa．Farther consideration especially about whether this device can harvest stem cells from wide area of iliac bone and viability should be taken through invitroand animal experiments.
KeyWords‥Bone Marrow Transplantation，Bone Marrow Harvesting Device，Perfusion Method，Stem Cells
Abstract：The technique of spherical osteotomy without bone lossis useful
for surgeries such as the rotational acetabular osteotomy or the acetabular
socket revision．Curved chisels have been used so far．This method of using
a curved chisel has an advantage ofless bone loss，but has a difnculty
in controlling the blade and in perfbrming osteotomies precisely spherically
within short time．Then，weh ave developed a novel curved－bladed Tuke
saw．Using this device in combination with the navigation system，we tried
performing spherical osteotomies precisely，within short time，without
X－ray radioscopy． In this study，using this device，we tried spherical
osteotomies for Sawbone blocks under the navigation．The distance errors
of the actual osteotomy surface from th eplanned sphere surface were measured
at various positions of the osteotomy line on the section of blocks．The
distance error is larger outward from theplanned sphere surface when the
osteotomy surface is deeper，andthe maximum value is about 2．1mm． This
novel device is enough useful for practical use．
Abstract：We have developed a surgical simulation system that replicates the performance of surgical maneuvers on elastic organs．In order to realize this system，we have constructed an elastic organ model under the name of sphere－filled mdel．This model is applied to our surface organ model and is suited for real－time simllation．In this research we will present a real－time deformation method for three-dimensional volume datasets dbtained by dle observational equlpment sudh as MRI or CT.In order to deform volume data，a voxel group is linked to a neighboring sphere filling with elastic organ．In this approach，we adopted therhombic dodecahedron as the formation of the voxel group when selecting the face center cubic(FCC）method．Because this formation makes it impossible for voxels to overlap mutually and the spheres in connection with voxels are decided naturally．The formation follows the motion of each sphere．The volume rendering method is Maximum Intensity Projection（MIP）method to observe theinternal structure of organs．In addition to be connected with aforce feedback device for surgical simuladon，various surgical maneuvers such as pushing，pinching，and incision for volume data through the sense of touch are realized in this system．
Keywords：virtual surgery system，volume data，real－time deformation
Abstract：Currently，preoperative images acquired by various modalities are used for the interpretation of the anatomy of thetherapeutic area．However，intraoperative deformation of the organs makes it difncult to visualize the intemal structures of these organs during the operation．The aim of our study is to develop a data fusion system to support open surgery．In this paper，we have focused on an intraoperative measure－ment of organ surface deformation．The stereo camera captured color markers on theobiect's surface and converted them into 3D data with color information．We obtained intraoperative moving surface data using this color information．The results were presented as the moving surface data superimposed onto the camera image，which is a preliminary step towards fusing real－world and virtual－world data．By usinga stereo camera，the movement of surface data could be obtained without physical contact and in real－time．There－fore the results suggest that the method is useful for intraoperativemeasurement and image navigation．
Keywords：Data Fusion，Open Surgery，Stereo Camera，Real－time Imaging
Abstract：We have been developing a virtual surgery system whichis capable
of simulating surgical maneuvers on elastic organs，the structure of which
was obtained from a patient.An integral part of this system is an elastic
organ model enabling real－time deformations.In order to perform such maneuvers
in real－time， we have created a deformable organ model called a sphere－filledmodel
that is suited to real－time simulation and quantitative deformation．Furthermore，we
have connected a dual force feedback device to this model to provide the
user with sensory feedback，specifically sensation of touch and a sensation
of force.However，the model in the initial stage became problematic when
facedwith incision deformation.In this paper，we would like to present
the deformation of the incision and resection．Moreover，how the deformation
of the internal structures can be observed via the intemal sphere's behavior
is discussed・By applying this model，we will be able to perform realistic
medical procedures．
Keywords：virtual surgery，sphere－filled model，incision and resection
Abstract－This paper reports the feasibility study in Vivo of fast motion
tracking and image registration method embedded inmagnetic resonance image（MRI）guided
surgery using projection profile matching．Projection profile matching
is the method to estimate the position of the object by matching projection
profiles before and after the motion.The profile can be calculated from
MR echo without phase encoding，thus the advantage of this technique over
any other method based on image processing is that only one echo data and
the baseline image is required to estimate the position of the object per
each direction．We implemented the method onto the clinical scanner，and
conducted in Vivo experiment tracking the motion of a human liver to evaluate
the feasibility. Our implementation can perform two－dimensional organ
motion tracking with time resolution of four times as repetition time（TR）retrospectively.Results
show that the method successfully performed on in Vivo human liver study
with enough speed for MRI guided surgery．
KeyWords：MRI－guided surgery，Motion tracking，Projection profile matching
Abstract：Simulation systems of organ deformation are being introduced
into laparoscopic surgery as well as surgical training and planning．The
realistic tracing of tumour and blood vessel during liver surgery requires
the deformation analysis based on physical principles．Finite element method
is a useful tool for this purpose due to itsclear physical background．In
this work the simulation of liver deformation in liver surgery is carried
out by introducing nonlinearfinite element method．The realistic deformations
of liver are obtained by taking the geometrical and material nonlinearities
into account．
Keywords：Deformation Simulation， Liver Deformation，Nonlinear Finite Element
Abstract：There is a need to measure the biomechanical properties of liver
tissues to make accurate surgical simulation model． In this report，we
describe the measurement of the mechanical properties of cylinder－form
specimen using surgical bonding glue.It makes easier to define the boundary
conditions of the specimen.Furthermore，we performed elongation and compression
test continuously.We will also be able to determine the effects on the
strain properties of liver as a result of changes in loading rates，tissue
size and other parameters.The result will be useful for FEM analysis and
itwill enhance the accuracy of simulation model.
Keywords:Mechanical properties，liver tissue，elongation test
【Abstrutt】
Liver cancers often occur frequently in cirrhotic（highly fibrotic）liver．It is difncult to diagnose the liver cancer precisely before the operation by normal CT images．We did the followingexamination for the purpose of the automatic detection and diagnosis of the liver cancer．Histogram and profile of CT value of the cases which had a hepatic resection in our facilities was analyzed．It was conceivable that it could be the assistance of the automatic detection and also qualitative diagnosis of the liver tumor by making quantitative analysis of the CT value．
KeyWords：Liver tumor；MDCT，3－D Histogram
Abstract：We have developed an imaging system for free and quantitative observation of human locomotion in a time－spatial domain（4D）by way of real time imaging．The system is equipped with 60 computer controlled video cameras to record human locomotion from all angles simultaneously.Images are installed into the main graphic workstation and translated into a 2D image matrix．Observation of the subject from optional directions is able to be performed by selecting the view point from the optimum image sequence in this image matrix．This system also possesses a function to reconstruct 4D models of the subject's moving human body byusing 60 images taken from all directions at one particular time．And this system also has the capability to visualize inner structures such as the skeletal or muscular systems of the subjectby compositing computer graphics reconstructed from the MRI dataset．We are planning to apply this system to clinical observation in the area of orthopedics，rehabilitation and sports science．
Keywords：4D humanmodel，human locomotion，time－slice camera，data fusion
【Abstract】As an intraoperative test for stability of the hip joint in
total hip arthroplasty（THA），the range of motion is usually tested in
2 critical positions：flexion plus internal rotation，and extension plus
external rotation．There have been，however，few reports on the ranges
of motion including the specific motions described above in actual hips．To
study the individual variation of these ranges of motion and their correlationsto
some anatomic parameters including CE angle，acetabular anteversion，femoral
anteversion，head neck ratio and neck shaft angle，computer measure ments
with collisjon detection of the pefvisand femur were performed using CT
images of the anatomically normal hips in 40 patients and the dysplasia
hips in 25 patients．Our data suggested that the patients with higher acetabular
and femoral anteversion and smaller CE angle require higher flexion and
internal rotation at 900 flexion until bonyimpingement occurs．Therefore，the
range of motion should be tested according to the original bony structure
of the hip joint in these cases．
KEYWORD：range of motion，computer simulation，collision detection
Abstract：We present a new method for 2D／3D registration by eliminating
low correlation regions.In 2D／3D registration，overlapof peripheral structures
make the error of registration.By eliminating overlap regions，more accurate
registration can be achieved．To determine them．correlation values of
sub－devided regions are calculated．Then，the registration is performed
except to low corre－lation regions．We show the result of preliminary
experiments and the advantage of this method．
Keywords：2D／3D Registration，Region elimination
Abstract：The ability to evaluate fetal growth in utero is important in
perinatal management.The identification of growth abnormalities can assist
in decisions regarding fetal and maternal management and clinical intervention.Ultrasound（US）imaging
is the standard obstetrical imaging technique used for the prenatal diagnosis
of suspected fetal abnormalities．However，recent MR irmging may provide
more infbrmation than US about the anatomical details of malformed fetuses
and has the potential capability to yield functional information aboutabnormal
organs.It is important to know fetal lung maturity or brain maturity for
fetal surgery．The purpose of this study is to measure fetal lung volume，lung／liver
intensity ratio and brain／liver intensity ratio with MRI for the prenatal
diagnosis of congenital diaphragmatic hernia and hydrocephalus.
keywords：MRI，prenatal diagnosis，congenital diaphragmatic hernia，hydrocephalus
Abstract：In total hip arthroplasty（THA），dislocation is one of the most
serious complications．And generally，the daily motion of patients after
THA is limited to some extent in order to prevent dislocation．However，the
causes of the dislocation depends on the skeletal structures，alignment
of implants，or the characteristics of the patient’s movement．So predicting
dislocations and giving precise guidance for postoperative daily motions
is difncult for clinicians．We have developed a computerized 4－dimensional
human model with musculature that can visually represent the patient's
skeleton and muscles，and by using this modelwe can predict the risk of
dislocation using computer simulation．At first，we construCted a 3－dimensional
skeletal model of the patient's lower extremlty from CT data．To achieve
an accuratemodel，we replaced the implant model with the CAD data．Then
we developed a model of the five muscles related to the movement ofthe
hip joint．Each muscle was represented as one or several strings that expand
and contract．By using this model，clinicians can predict the potential
for dislocation or recognize the causes of dislocation including the influence
of the muscles．
Keywords：4D human model，total hip arthorplasty（THA），dislocation
【Abstract】
Purpose of this study is to demonstrate the locus of the dynamicloading on the knee in stance phase of the gait using 3D CT simulation program and compare the locus between normal subjects andthe patients with medial osteoarthritis of the knee（OA）．11knees of 8 patients with OA（Kellgren’s Grade 3 on radiograph）and10 knees of 5 controls with normal knee were subjects in this study．CT images of the lower extremity were taken with skin marker for gait analysis，and dynamic data in gait was obtained from Vicon motion analysis system in each subject．The marker positions between CT image and gait analysis were matched．We developed3D CT simulation program for demonstrating the locus of the dynamic loading on the knee in stance phase of the gait.This programcalculates the cross point of knee joint surface and Mikulicz’smechanical axis．Using this program the loading point on the knee joint in stance phase were calculated in each subject and compared the distance from joint center between the patients and controls．On loading response peak and terminal stance peak in gait，the loading points on the knee joint of the patients with OA passed more inside than that of the controls．
【Keywords】locus of the dymamic loading on the knee，Mikulicz’s mechanical axis，medial osteoarthritis of the knee
Abstract
In the domain of orthopaedic surgery，the knowledge of three－dimensional（3－D）kinematics after total knee arthroplasty（TKA）is highly important to validate innovative prosthesis designs and diffbrent surgical strategies．2－D／3－D registration technique using CAD models of metallic knee components and fluoroscopic images enables 3－D pose estimation of the knee prosthesis．In this study，we have developed the 3－D kinematics analysis system using this technique，validated the accuracy of this system and applied this technique to in vivo．
KeyWords：total knee arthroplasty，kinematics，2－D／3D registration
Abstract：The purpose of this study is to apply Three dmensional image
to mandibular movement data，and to discuss the clinical utility of this
informationn．The subject was a 26-year-old female of volunteer who has
no missing teeth and no morbid findings in clinical examinations．Prior
to taking the computerized tomography（CT），mandibular were measured using
POLARIS. The skull,mandibular and clutches were reconsuructed into a Three-dimensional
image from the dbtainedCT data. The relationship markers and anatomic structures
were computed on CT imaging．The movements in each region of the anatomic
structures were calculated using the data from the CT and POLARIS．The
Three- dnmional imaging on the computer monitor was sysnchronized with
the human movement by a real-time imaging system. In intercuspal position
and all sorts of mandibular movents,we could dbserve various condyle mpvements
including the relationship of the position between the condyle and the
eminence-fossa． By using this system,we could acquire much more information
than by previous analysis of mandibular movements．It was suggested that
Four-dimensional analysis would be usefui in studying thepathogenesis is
of disease and convalescmce in TMD．
keyword：Four-dimensional analysis，Mandibular movement,Real-time imaging
Abstract：In1982．Farrar emphasized that articular disc displacement
is concermed with occlusion and condylar position. And there was reported
that posterior movement of the condy is the cause of articular disc displacement.
But such theory has not been proved until today.Because,from theanatomical
point of view it cannot consider that the condyle moves easily to posterior
so much．Furthermore there was no method to evaluate of condylar movement
including its position for the temporal bone. In this report, 4-dimensional
analysis of mandibular movement was performed for the patient with temporomandebular
disorders The subiect was a 57-year old female.The movement of nmandible
was recorded by a 6-degree of freedom jaw tracking device(MM-JI-E，Shofu
co.).Prior to taking the computerized tomography (CT),mandibular movements
were measured. The skull,mandible and markerswere reconshcted into a 3-dimensional
image from the obtained CTdata．Then the 3－demansional imaging on the
computer monitor was applied by the movement data. In this study ,4-dimensional
analysis of mandebular movement wasperfoumed,and became clear that the
condyle can move back so much in the patients sith internal derangement.
It was suggested that articular disc displacement is concerned with the
posterior movement of the condyle.
Keyword：Four dimensional analysis，Mandibular movent,Temporomandibular disorders