| title | author | page |
| Technical Trend of Semiconductor Detector for Nuclear Medicine |
Nobuyuki NAKAMURA |
3-8 |
|
Key words : CdZnTe, CdTe, Semiconductor, Radiation detector, Nuclear Medicine
|
|
Abstract : In recent years, the development of semiconductor detectors for
nuclear medicine application has been underway in earnest. This significant
technical innovation owes itself to the rapid progress of the manufacturing
technology of semiconductor elements. Among these elements, the II-VI
compounds CdZnTe and CdTe have been gaining special attention because it is
possible to use them at the room temperature. For CdZnTe, the ut product of
hole is relatively small, resulting in the deterioration of energy resolution
from insufficient carrier collection. However, by revising the electrode
structure, it is possible to cancel the holes and to collect almost all
electrons, thereby making it possible to collect energy information correctly.
For CdTe, it is possible to supply high-voltage and decrease leak current by
using Schottky electrodes made of Indium. As a result, energy resolution and
time response can be improved. Although problems such as a relatively large
defective ratio and the lack of mass production techniques remain with CdZnTe
and CdTe, other factors such as technical performance of the elements,
assembly techniques and analog integrated-circuit technology are at levels
such that production of new semiconductor detector systems for nuclear
medicine can be realized.
|
| title | author | page |
| Scatter, Attenuation and Detector Response Correction of SPECT |
Hiroyuki SHINOHARA, Tomoaki YAMAMOTO, Hideharu SUGIMOTO,
Takeyuki HASHIMOTO, Munehiro TAKAHASHI, Takashi YOKOI |
|
|
Key words : SPECT, Scatter correction, Attenuation correction, Detector response correction
|
|
Abstract : Scatter, attenuation and detector response in single photon
emission computed tomography (SPECT) imaging contribute to the error in
quantification of activity concentration and decrease in contrast of
reconstructed images. Correction methods for these three factors are
introduced and related physical phantom studies are reported.
|
| title | author | page |
| Metacomputing Environment for Magnetoencephalography (MEG) |
Susumu DATE, Yuko MIZUNO-MATSUMOTO, Shinichi TAMURA, Yoshinobu SATO,
Reza A. ZOROOFI, Yuji TABUCHI, Shinji SHIMOJO, Youki KADOBAYASHI,
Haruyuki TATSUMI, Hiroki NOGAWA, Kazuhiro SHINOSAKI,
Masatoshi TAKEDA, Tsuyoshi INOUYE, Hideo MIYAHARA |
|
|
Key words : Networking, MEG, Brain function, GLOBUS, MPI, Parallel computing
|
|
Abstract : In this paper, we propose a method for evaluating brain function
using magnetoencephalography (MEG) in a metacomputing environment, that is, a
widely distributed computing environment. For the metacomputing environment,
we adapt the GLOBUS system, which provides various software components for
this environment, and its API (Application Programming Interface) for MPI
(Message Passing Interface), called MPICH-G. Through the use of this
metacomputing environment, three processes (acquisition of data from MEG,
analysis, and visualization) are smoothly integrated into a single seamless
process on the wide area network. As a result, the total time and cost of
reaching the final diagnosis are reduced. We may also be able to geometrically
distribute these three processes in the future, which would support remote
diagnosis. In addition, with the use of MPI, analysis can be performed by
parallel processing. We constructed a small-scale system on the local area
network and implemented analytical processing on a massively parallel
supercomputer, Exemplar. Our results showed that we could achieve an 8-fold
increase in parallelism in the analytical processing, and that our graphical
interface for MEG should be very helpful in realizing an efficient diagnostic
system for brain function analysis.
|
| title | author | page |
| Propagation of Epileptiform Discharges Using Wavelet-crosscorrelation Analysis in MEG |
Yuko MIZUNO-MATSUMOTO, Shinichi TAMURA, Yoshinobu SATO,
Reza A. ZOROOFI, Susumu DATE, Yuji TABUCHI, Kazuhiro SHINOSAKI,
Satoshi UKAI, Ryohei ISHII, Tsuyoshi INOUYE, Haroyuki TATSUMI,
Youki KADOBAYASHI, Shinji SHIMOJO, Masatoshi TAKEDA, Hideo MIYAHARA
|
|
|
Key words : Wavelet-crosscorrelation analysis, Non-stationary analysis, Epilepsy, Propagation, Localization, Magnetoencephalography (MEG)
|
|
Abstract : Wavelet-crosscorrelation analysis, a new non-stationary method, is
proposed as a technique for revealing the locations of epileptic foci and the
propagation of epileptiform discharges. A patient with simple partial seizures
was examined using whole-head magnetoencephalography (MEG). The time-lags
between all sensor sets were calculated to obtain the maximum
wavelet-crosscorrelation coefficient. The results showed that this method is
useful for evaluating the epileptogenesis of epileptic phenomena seen in MEG
and EEG studies. This method can be used to determine the propagation time and
the correlation of two non-stationary waves containing various frequency
components.
|
| title | author | page |
| Improved Registration Method for Correcting Local shifting on DSA images |
Kyoichi HIROSHIMA, Junji NISHINO, Tomohiro ODAKA, Hisakazu OGURA,
Testuya FUKUSHIMA, Yasuhiro NISHIMOTO, Masato TANAKA,
Hiroyuki KOMURO, Yasushi ISHII |
71-83 |
|
Key words : Digital subtraction angiography (DSA), Misregistration, Registration, Motion artifact
|
|
Abstract : We have investigated digital subtraction angiography (DSA) images,
which are used to extract blood vessels. In this paper, we propose a new
algorithm for eliminating motion artifacts using a local movement method over
the image. The proposed method was found to correct artifacts in the images
extremely well. Peripheral blood vessels around the nasal cavity and/or the
orbit, which could not be observed well by conventional registration methods,
were extracted clearly by the proposed method.
|
| title | author | page |
| Comparison of Iterative Image Reconstruction Methods in Single Photon Emission CT |
Hiroshi URABE, Kotoko MORIKAWA, Koichi OGAWA |
84-93 |
|
Key words : Medical imaging, SPECT, Image reconstruction, Iterative methods
|
|
Abstract : In this paper, we compare the quality of images reconstructed by
ART (algebraic reconstruction technique) and SIRT (simultaneous reconstruction
technique ), GRADY ( gradient method ), CONGR ( conjugate gradient method ),
ML-EM ( maximum likelihood - expectation maximization ), and MAP-EM ( maximum
a posteriori - EM ),which are known iterative image reconstruction methods.
|
| title | author | page |
| Flat Panel Displays for Diagnosis and Monitoring of Medical Imaging
|
Hiroshi TSUTSUI |
101-109 |
|
Key words : Flat Panel Display (FPD), Liquid Crystal Display (LCD), Plasma
Display Panel (PDP), Radiography, Medical imaging
|
|
Abstract : Recently almost of visual data obtained by the modalities
containing CR, x-ray CT, MRI and Ultrasound have been treated digitally, and
the diagnosis using CRTs and the tele-radiography have been utilized. On the
other hand, the technologies of the flat panel displays (FPD) like the Liquid
Crystal Display (LCD), the Plasma Display Panel (PDP) and so on, are improved
and performances of these displays become to be acceptable for the diagnostic
and the clinical use in the past few years. In this paper, the mechanism, the
performance and the potential of the FPDs for medical applications are
described.
|
| title | author | page |
| Application of Surgical Simulation and Navigation System with 3D
Imaging |
Kenshi KANEKO, Yasushi FURUTA, Nobuaki ISHII, Chihiro TAKAHASHI,
Satoshi TERAE, Kazuo MIYASAKA |
121-126 |
|
Key words : Computer-assisted Surgery, Navigation system
|
|
Abstract : Surgical navigation and simulation systems with 3D imaging allows
operations to be more precise. The advances in diagnostic imaging, especially
in the fields of computed tomography (CT) and magnetic resonance imaging (MRI)
and improvements in data processing technology enable real time interactive
surgical localization with great accuracy. We present the composition of this
system, the method of processing preoperative 3D-data, correlating this data
with an actual surgical space, and discuss clinical applications, mainly in
neurosurgery.
|
| title | author | page |
| Detailed Extraction Method for the Lung Region Using the Active
Cylinder Model in Chest X-ray CT Images |
Toshiaki OKUMURA, Shinji YAMAMOTO, Tohru MATSUMOTO, Yukio TATENO,
Takeshi IINUMA, Mitsuomi MATSUMOTO |
136-148 |
|
Key words :Image processing, Region extraction, Active Cylinder Model, Chest
X-ray CT images
|
|
Abstract : We are developing an automatic system for recognizing lung cancer
shadows in chest X-ray CT images to support lung cancer mass screening. The
development of an extraction method for the lung region in chest X-ray CT
images is an important preprocessing method for the above computer-aided
diagnosis system. We have already proposed a model-based rough extraction
method for the lung region using a typical patient sample as a model. This
method involves the affine transformation of the model to fit it to the input
image, and the transformed model image is defined as the rough lung region for
the input image. In this paper, we propose a detailed extraction method using
the Active Cylinder Model. The results of the rough extraction method are
used as initial control points in the Active Cylinder Model. The control
points are moved based on the internal energy and the image energy. The
internal energy is position information of the adjoining control points, and
the image energy is image information such as edge information calculated from
the input image. This method was applied to 68 sample chest CT images, and
was found to be very effective and practical.
|
| title | author | page |
| Image Management System for Integrating Distributed Servers with a
Web Browser in a Radiology Department |
Masato TANAKA, Hideki UESAKA, Yasutaka KAWAMURA, Hiroyuki KOMURO,
Harumi ITO, Yasushi ISHII, Yoshiharu YONEKURA, Norihiro SADATO,
Hisakazu OGURA |
149-157 |
|
Key words : Masato TANAKA, Hideki UESAKA, Yasutaka KAWAMURA, Hiroyuki KOMURO,
Harumi ITO, Yasushi ISHII, Yoshiharu YONEKURA, Norihiro SADATO,
Hisakazu OGURA
|
|
Abstract : Sixteen years ago, we introduced a medical image management system
using microfilms at the Department of Radiology of Fukui Medical University
Hospital. This system is very useful for clinical education and research.
However, it has some significant shortcomings, such as a decrease in image
quality, loss of microfilms, high running costs, and insufficient storage
space. We have developed an electronic medical image management system based
on distributed data resources which we plan to use to expend and complement
our existing microfilm-based system. Medical image acquisition is performed
automatically when an operator sends images to the laser imager, and the
captured images are sent to a server called the Image Server using the DICOM
protocol. The Image Server compresses the images using the JPEG method and
prepares two types of images: a full image with the same number of pixels as
the original image and an abbreviated image with one half the number of
pixels. Then, the Image Server sends the attributes of the images to a Total
Control Server. The Total Control Server maintains and updates an index file
for searching, and integrates the distributed resources. Client computers
sited at the clinical offices search the results of examination by
communicating with the Total Control Server and display the images received
from the respective image servers directly using a Java applet executed on a
web browser. We have used this system in actual practice for 10 months and
have stored 150 million full and abbreviated images (total disk volume: 12.1
GB). This electronic system is able to maintain high-speed response due to the
distributed resources and the reduction in image volume, and has become
indispensable in ensuring smoothly examinations and routine diagnostic work.
|
| title | author | page |
| Elasticity Analysis by MR Elastography using the Instantaneous
Frequency Method |
Osamu OSHIRO, Mikio SUGA, Kotaro MINATO, Jun OKAMOTO, Osamu TAKIZAWA,
Tetsuya MATSUDA, Masaru KOMORI, Takashi TAKAHASHI |
158-166 |
|
Key words : Elasticity, MRI, MR Elastography, Instantaneous Frequency Method
|
|
Abstract : This paper describes a calculation method for estimating the
elasticity of human organs using magnetic resonance elastography (MRE) images.
The method is based on the instantaneous frequency method, which is very
sensitive to noise. Therefore, the proposed method also incorporates a
noise-reduction function. In the instantaneous frequency method, Fourier
transform is applied to the measurement signal. Then, inverse Fourier
transform is performed after the negative frequency component is set to zero.
In the proposed method, noise is reduced by processing in which the positive
higher frequency component is also set to zero before inverse Fourier
transform is performed. First, we conducted a simulation study and confirmed
the applicability of this method and the noise reduction function. Next, we
carried out a phantom experiment and demonstrated that elasticity images could
be generated, with the gray level corresponding to the local frequency in MRE
images.
|
| title | author | page |
| Virtual Imaging of the Lung Based on Computational Morphology |
Hiroko KITAOKA, Shinich TAMURA |
173-178 |
|
Key words : Computer, Morphology, Virtual imaging, 3D model, Simulation, Lung
|
|
Abstract : We propose an entirely new approach named "virtual imaging of an
organ based on computational morphology". The computational morphology
includes the structural model of the organ and mathematical models of the
diseases, and generates a virtual organ in computer. The virtual organ is then
divided into cubic voxels with the side of 0.5 mm, and virtual CT value for
each voxel is calculated according to the tissue property within the voxel.
The validity of the model is examined by comparing the virtual images with the
clinical ones. Based on the models validated, image analysis methods for
diagnosis are developed.
|
| title | author | page |
| Successive Approximation Algorithm for Cancellation of Artifacts in
DSA Images |
Raiko FUNAKAMI, Kyoichi HIROSHIMA, Junji NISHINO, Tomohiro ODAKA,
Hisakazu OGURA, Tetsuya FUKUSHIMA, Yasuhiro NISHIMOTO, Masato TANAKA,
Harumi ITO, Kazutaka YAMAMOTO |
199-206 |
|
Key words : Digital subtraction angiography (DSA), Misregistration,
Registration, Motion artifact
|
|
Abstract : In this paper, we propose an algorithm for cancellation of
artifacts in DSA images. We have already proposed an automatic registration
method based on the detection of local movements. When motion of the object is
large, it is difficult to estimate the exact movement, and the cancellation of
artifacts may therefore fail. The algorithm we propose here is based on a
simple rigid model. We present the results of applying the proposed method to
a series of experimental X-ray images, as well as the results of applying the
algorithm as preprocessing for a registration method based on local movement.
|
| title | author | page |
| Analysis of Morphology of Pulmonary Nodules Using a Fourier
Descriptor |
Mitsuru KOMIZU, Hisayasu MATSUO, Yoshio YANAGIHARA, Kiyoshi MURATA,
Masashi TAKAHASHI, Satoru MATSUO, Hiromitsu HAMA |
207-216 |
|
Key words : Fourier descriptor, Pulmonary nodule on CT image, Morphological
feature, Computer aided diagnosis
|
|
Abstract : The usefulness of computer aided diagnosis (CAD) systems in the
differential diagnosis of pulmonary nodules detected by lung cancer screening
CT has been widely acknowledged. In this study, we quantified the
morphological features of such nodules and assessed whether they could be used
for objective evaluation to improve diagnostic accuracy, based on hypotheses
regarding differences in growth appearance between benign and malignant
nodules. Quantification was achieved for both high-resolution CT images and
simulation images using Fourier description. Benign pulmonary nodules (
inflammatory scars) showed high amplitude in the lower harmonics, while malignant nodules (lung cancers) showed high amplitude in the higher harmonics. These
values were compared by Mahalanobis generalized distance multivariate
analysis. The mean predictive values of this analysis for the inflammatory
scar and lung cancer groups were 85% and 90%, respectively. The mean
predictive value for the two groups was 87.5%.
|
|
Correspondence:
E-mail me
|
| title | author | page |
| Fuzzy Computation for Detecting Edges of Low-Contrast Substances
in Urinary Sediment Images |
Ning-Feng ZENG, Keiji TANIGUCHI, Sadakazu WATANABE, Yutaka NAKANO,
Hiroyuki NAKAMOTO |
217-229 |
|
Key words : Edge detection, Low-contrast substance, Urinary sediment image, Fuzzy reasoning, Edge amelioration
|
|
Abstract : This paper proposes a robust model for detecting the edges of
low-contrast substances in urinary sediment images. The edge detection
process is divided into four stages: denoising, scaling, detection, and
amelioration. In the first stage, the noise is reduced using optimum local
statistics. In the second stage, the intensity is classified into different
scales, and our proposed algorithm is then used to detect the edge of each
scale. In the third stage, the edge is detected based on both the local pixel
and the characteristics of neighboring pixels. It is difficult to distinguish
between the intensity of low-contrast substances and that of the background,
but local variance is much more easily distinguished. Edgeness (edge sharpness
) is evaluated by applying the fuzzy membership function of the variance and
other fuzzy membership functions which are based on local pixel
characteristics. In the final stage, although most of the edge segments are
detected perfectly, some parts may remain ambiguous if noise is present. In
this case, some of the detected edges that are false segments can be
ameliorated using certain local features of the object based on the overall
view. The experimental results show that our scheme is quite robust. This
method is capable of detecting the closed edges of low-contrast substances
with accuracy comparable to that of the human eye.
|
| title | author | page |
| Morphological Method for Automatic Extraction of the Coronary
Arteries |
Ying QIAN, Shigeru EIHO |
231-239 |
|
Key words : Morphological operation, Coronary artery, Image processing
|
|
Abstract : Coronary arteriography is a clinically important diagnostic tool
for the evaluation of coronary artery disease, and can provide detailed
information. For the quantitative assessment of the coronary arteries, it is
necessary to extract the edges of the arteries from coronary arteriograms.
Several studies concerning the extraction of vessel edges have been
published, and automatic extraction of vessel edges has been used in clinical
diagnostic systems. However, these methods are not satisfactory, because
manual modification by the operator is unavoidable in some cases. To reduce
manual operation, accurate and automatic extraction of the coronary arteries
is necessary. In this paper, we propose a new technique for automatic
extraction of the coronary arteries using morphological operators. This method
includes the following steps: 1) contrast enhancement using a morphological
Top-Hat operator, 2) enhancement of thin vessels and reduction of pulse noise
using a morphological erosion operator, 3) elimination of obvious background
pixels by semi-binary thresholding, and 4) extraction of the coronary arteries
by labeling and counting the area.
|
| title | author | page |
| Evaluation of Diaphragmatic Movement during Full-Inspiration
Breath-Holding |
Toshizo KATSUDA, Shigeru EIHO, Chikazumi KURODA |
240-244 |
|
Key words : Full-inspiration breath-holding, Lung imaging, Diaphragmatic
movement and movement direction
|
|
Abstract : In this article, we describe diaphragmatic movement during
full-inspiration breath-holding. Diaphragmatic movement was analyzed on
angiographic films during 24-second full-inspiration breath-holding in 36
patients. The distance between the liver apex and the upper edge of the field
was measured on 15 films in each patient. The direction of movement was also
analyzed. In more than 60% of patients, the diaphragm moved in the cranial
direction during long-duration full-inspiration breath-holding. In lung
imaging, scanning should be performed from base to apex because diaphragmatic
movement is more often in the cranial direction.
|
| title | author | page |
| Fuzzy Information Granulation on Three-Dimensional Medical Image
Processing |
Yutaka HATA, Syoji KOBASHI, Yuri KITAMURA, Toshio YANAGIDA |
681-687 |
|
Key words : Fuzzy information granulation, Medical image segmentation,
Magnetic resonance imaging, Magnetic resonance angiography, Human brain,
Blood vessel
|
|
Abstract : This paper describes an application of fuzzy information
granulation (fuzzy IG) to medical image segmentation problems. The issues are
whole brain extraction from human brain magnetic resonance (MR) images, and
blood vessel extraction from three-dimensional time-of-flight (TOF) MR
angiography images. These methods are based on both the fuzzy IG concept and
physician's knowledge represented by fuzzy linguistics.
|
| title | author | page |
| Prediction of Resultant Profile After Orthognathic Surgery Employing
Neo Fuzzy Neuron |
Noriaki SUETAKE, Ichiro MASUI, Takeshi YAMAKAWA |
688-697 |
|
Key words : Neo fuzzy neuron, Orthognathic surgery, Prediction, Profile
|
|
Abstract : During presurgical planning of orthognathic surgery, clinicians
predict a resultant facial profile which is much influential in facial
esthetics. Many researches to predict a postoperative profile were reported,
most of which used linear regression analyses with changing value of profile
landmarks and skeletal landmarks. But the prediction employing changing
values of the landmarks are deficient in information of face size and
thickness of the soft tissue. Also, a profile change is a non-linear
result from the interaction of not only skeletal movement but also soft
tissue thickness or tonicity. This paper proposes an innovative prediction
method by the neo fuzzy neuron. Materials used in this study were lateral
cephalograms taken before and after surgery of 38 patients had bimaxillary
orthognathic surgery. The skeletal and facial landmarks were measured
two-dimensionally. The preoperative X-Y coordinates of hard and soft tissue
landmarks were input variables; postoperative coordinates of soft tissue
landmarks were output. Comparing prediction errors between the neo fuzzy
neuron method and the linear multiple regression method, the neo fuzzy
neuron method was most suitable for prediction of resultant profile after
orthognathic surgery.
|
| title | author | page |
| Artificial Immune Network for Feature Extraction of Patterns |
Toshiyuki SHIMOOKA, Yasufumi KIKUCHI, Koichi SHIMIZU |
709-714 |
|
Key words : Pattern recognition, Feature extraction, Immune system,
Idiotypic network
|
|
Abstract : The application of an idiotypic network model to the feature
extraction of patterns was attemptted. When we assume an observed pattern as
an antigen, we can consider the immune system as the pattern-matching system
using antibodies as partial templates. The antigen can be represented by
steady-state solution that is the internal image resulted from the interaction
of antibodies. Using the Farmer's mathematical model, the dynamics of simple
cyclic networks were studied. It was found that we could classify observed
patterns by analyzing steady-state solutions. Through this study, the
usefulness of the idiotypic network for feature extraction of patterns was
verified.
|
| title | author | page |
| Fractal Dimension Texture Analysis of Brain Function Images
in Diffuse Encephalopathy |
Koji UEMURA, Hinako TOYAMA, Kenji ISHII, Akihiko UCHIYAMA |
715-723 |
|
Key words : Fractal dimension, Box count method, Diffuse encephalopathy,
Cortical surface, Cerebral blood flow, Glucose metabolism
|
|
Abstract : In toxic or infectious encephalopathy, PET images of cerebral
blood flow and the cerebral metabolic ratio of glucose (CBF and CMRGlc,
respectively) are abnormally heterogeneous across the cerebral cortex with
a speckled appearance. In this study, we evaluated the nature of the
heterogeneity of 3D-cortical surface images quantitatively by fractal
dimension texture analysis. The 3D-brain surface was projected onto a
2D-plane by Mollweide projection. Then, after smoothing the PET images of
the projected brain surface an appropriate number of times, the mean fractal
dimension was estimated by the box count method. The fractal dimension
reflected the grain size of the speckle distribution, which differed from
the absolute values of CBF and CMRGlc. The fractal dimension values in CBF
images were higher than those in CMRGlc images. In patients with brain
disease, the fr actal dimension values were lower than those in normal
subjects in CBF images. The results suggest that this method allows
quantitative measurement of the cortical surface texture in a 2D plane and
is useful for analyzing PET and SPECT data of patients with diffuse
encephalopathy.
|
| title | author | page |
| System for Selecting and Generating Images Controlled by Eye
Movements Applicable to CT Image Display |
Yoshio YANAGIHARA, Hiromitsu HAMA |
725-733 |
|
Key words : Eye control application, CT image selection mechanism, Eye gaze
measurement, Medical image display system, Computer-assisted system
|
|
Abstract : Several methods for controlling computer systems by eye movements
have been studied recently as user interfaces for computers. On the other
hand, overlaying medical images on the patient will lead to the development
of new diagnostic imaging techniques. When the is performing other tasks
simultaneously, gaze control is a useful interface for the display system.
We save developed a new system for selecting CT images by eye movements.
The display area is set near the center of the visual field and the control
areas are arranged near the edges and in the corners. As there is some time
lag between the acquisition of eye-movement data and the generation of
display images, the system includes multiple specialized computers for each
process. To avoid the small validation of eye movements, a hysteresis
filter is employed. Experiments showed that the filter eliminated validation
more effectively than a moving-average filter. The processing time to display
selected images was 1.6 seconds for three images and 4.0 seconds for fifteen,
including the waiting time for effective control (1 sec).
|
|
Correspondence:
E-mail me
|
| title | author | page |
| Evaluation of Accuracy of Localizing an Intravascular Ultrasound
Probe for Endoscope Navigation |
Masatsugu HIRANO, Bo YANG, Yoshinobu SATO, Shinichi TAMURA,
Yoshifumi NARUMI, Munehiro MAEDA, Hironobu NAKAMURA |
735-739 |
|
Key words : Ultrasound image, Position marker, 3D localization, Endoscope,
Internal navigation
|
|
Abstract : We describe a method for identifying the 3D position and direction
of an ultrasound scanning probe introduced into the body to obtain endoscopic
images. A mark obtained by an ultrasound pulse from an external transducer is
shown on the endscopic image. The position of the mark (direction and distance
between the scanning probe inside the body and the marker transducer outside
the body) is extracted and measured on the scanned image. Then, the absolute
position of the ultrasound probe inside the body is determined by identifying
the absolute position of the external transducer with an optical localizer.
We performed experiments using phantoms several centimeters in size. The water
in the water tack was set to various temperatures. Actual position data
(ground truth) was obtained by scanning the ultrasound probe with the pen
probe of the optical localizer. Experiments for determining the 3D position
of the probe were performed at 18 points in the water tank. The average error
was 3.13¡Þ1.13 mm.
|
| title | author | page |
| Interactive MR Imaging Technique: Initial Experience |
Kenji SHIMIZU, Shigenori SUGATA, Teruhito MOCHIZUKI,
Junpei IKEZOE, Marc Van CAUTEREN, Joop J. van VAALS,
Shinichi TAMURA, Minoru TANAKA |
740-746 |
|
Key words : Interactive MR imaging, "Local Look" sequence, Interventional MR
imaging
|
|
Abstract : We describe an interactive magnetic resonance (MR) imaging
technique in which the scanning parameters are changed by operator interaction
during continuous scanning. This technique, combined with a single-shot
turbo spin-echo zoom imaging sequence, allows the operator to modify scan
parameters and observe the effects on the image within a few hundred
milliseconds. Specifically, the ability to perform interactive slice
positioning has been demonstrated with a normal volunteer. Providing
interactive scanning capabilities on a standard clinical scanner without
hardware modifications offers a practical and economical method for
supporting interventional and cardiac MR applications.
|
| title | author | page |
| Measurement and Evaluation of Local Tissues Elastic Modulus Using MR
Elastography |
Mikio SUGA, Kotaro MINATO, Tetsuya MATSUDA, Osamu OSHIRO, Kunihiro
CHIHARA, Makoto OHTA, Sadami TSUTSUMI, Masaru KOMORI, Takashi
TAKAHASHI, Jun OKAMOTO, Osamu TAKIZAWA |
769-776 |
|
Key words : Magnetic resonance elastography, Elasticity, Local wavelength
estimation, Multiple phase offsets, Shear modulus
|
|
Abstract : Magnetic resonance elastography (MRE) is a phase-contrast-based
method that can visualize propagating strain waves in materials. The
quantitative values of shear modulus can be calculated by estimating the local
wavelength of the wave pattern. Low frequency mechanical motion must be used
for soft tissue-like materials, because strain waves rapidly attenuate at
higher frequency. Therefore, it is difficult to estimate local wavelength with
high spatial resolution especially from noisy MRE. In the MRE sequence,
motion-sensitizing gradient (MSG) are synchronized with the mechanical cyclic
motion. MRE with multiple phase offsets can be generated with increasing
delays between the MSG and mechanical excitation. In this paper, we describe a
method of measuring local wavelength with high spatial resolution using MRE
with multiple phase offsets. We also describe MRE sequences and a vibration
system that can drive in the gantry of a magnetic resonance imaging system. To
confirm the reliability of this method, a computer simulation and phantom
study were performed. The shear modulus measured with various elastic objects
was well consistent with the value obtained by MRE and the mechanical method.
The shear moduli of various in-vitro and in-vivo tissues were also analyzed by
this method.
|
| title | author | page |
| Secure Method of Making the Sensible Human Data Available on the
Network |
Shigeki KUWATA, Hirohiko NAKANO, Yasushi MATSUMURA, Hiroshi TAKEDA
|
777-782 |
|
Key words : Security, Client/Server System, WWW, Attack, DoS
|
|
Abstract : It is considered most feasible to employ the web system on the
internet to make the sensible human data (SH data) open and to carry out the
efficient utilization of the data. This research aims 1) to develop the system
suitable for making the SH data available securely on the internet, and 2) to
verify whether the system can prevent threats to attack it. After developing
the system using the existing information technology, we verified its security
with well-known softwares for scrutinizing security holes. As a result, the
system proved to have a good performance enough to be used practically against
the known threats. Besides, we pointed out a security problem on the data
cached in a local browser which had not been noticed thus far. We considered
that installing our newly developed software would improve the quality of the
system in terms of security.
|
| title | author | page |
| Medical Application of Sensible Human Project Data |
Hiroshi OYAMA |
789-793 |
|
Key words : VR, CORBA, Sensible human project, Haptic, Medical system
|
|
Abstract : This paper describes that the haptic and shape data for the human
body acquired in the Sensible Human Project are used for a new application
that is useful for medicine education, clinical training and minimally
invasive surgery using robot technology permits the physical separation of the
patient and the surgeon. I might be able to use new diagnostic rules in breast
cancer, such as inspection of the incision after surgery or to compare the
results of self-examination, with pathology, and haptic data first. The
development of systems allowing this advance largely depends on the
construction of a tactile sense presentation device. I constructed a
neurosurgical training system for the National Cancer Center that constructs
scenes using OpenGL Volumizer, controlling the system using CORBA technology.
Research into problems created by the separation of these two is now necessary
and further technical developments are required. In conclusion, haptic data on
the human body may also be used in research on development of medical system.
|
| title | author | page |
| Advanced Computer-aided Detection System for Microcalcifications on
Mammograms by Improvement of the Morphological Filter |
Yohshihiro HAGIHARA, Hidefumi KOBATAKE, Shigeru NAWANO, Hideya TAKEO
|
795-804 |
|
Key words : Computer-aided detection, Mathematical morphology, Mammography,
Micro-calcifications, Breast cancer
|
|
Abstract : This paper describes an accurate computer-aided detection system
for microcalcifications on mammograms by improvement of the morphological
filter. The basic system is based on morphological processing using multiple
structuring elements. To improve the basic system, two new processing methods
are added. The first is a histogram-based morphological opening to suppress
artifacts. The other is a region expansion method that takes into
consideration the gradient of the background. To evaluate the effectiveness of
the proposed system, experiments on detection were performed. Test materials
for the experiments were 124 CR images. The true-positive detection rate of
the proposed system was 94.9% and the average number of false positives per
image was 0.516. The number of false positives per image was improved by 15.8%
in comparison with the conventional system. These experimental results
demonstrate the effectiveness of the proposed system.
|
| title | author | page |
| Basic Investigation of Fluorescent X-ray Computed Tomography Using
Synchrotron Radiation for Biomedical Use |
Quanwen YU, Tohoru TAKEDA, Toru YASHIRO, Tetsuya YUASA, Yasuhiro
HASEGAWA, Tsutomu ZENIYA, Kazuyuki HYODO, Jin WU, F. Avraham
DILMANIAN, Takao AKATSUKA, Yuji ITAI |
805-816 |
|
Key words : Fluorescent X-ray, Computed tomography, Synchrotron radiation,
Specific materials distribution, Nondestructive measurement
|
|
Abstract : Fluorescent X-ray computed tomography with synchrotron radiation
(FXCT) is being developed for imaging small amounts of target material in
biomedical objects. For optimal data acquisition by a highly purified
germanium detector, a performance study was carried out. Fundamental
examination of FXCT was performed to assess the quantitative detectability of
target material by obtaining phantom and FXCT images of the human thyroid
gland. To keep the counts acquisition error below 10%, the incoming counts to
the HPGe detector must be less than 10000 cps. FXCT clearly imaged 25-¦Ìg/ml
iodine solution in a phantom at a 200¡ß200-¦Ìm2 spatial resolution with a
200-¦Ìm slice thickness, and a linear relation between the concentration of
iodine and fluorescent X-ray counts was observed from 25¦Ìg/ml to 1000¦Ìg/ml.
The two-dimensional distribution of iodine within the thyroid gland was
depicted quantitatively. FXCT is thought to be a powerful tool for evaluating
the distribution of a specific material in a biomedical sample.
|
| title | author | page |
| Image Reconstruction by NMR Fresnel Diffractive Imaging Technique |
Satoshi ITO, Akiyoshi ONO, Yoshitsugu KAMIMURA, Yoshifumi YAMADA |
817-827 |
|
Key words : MRI, Diffractive imaging, Fast imaging, Angiography
|
|
Abstract : A new approach to MR angiography, the NMR diffractive imaging
technique, has been investigated. The expression for NMR signals obtained in
the NMR diffractive imaging technique is similar to the equation for Fresnel
diffraction in light waves or sound waves. Therefore, it is possible to
reconstruct an image focusing on any plane in the depth direction from data
scanned two-dimensionally by changing an imaging parameter in the
reconstruction step. To support this imaging technique, a coil system
composed of six coils was designed. Experiments were performed using an
ultra-low- field MRI scanner to acquire two-dimensional data in the proposed
technique. Even though blurred images outside the focus are superimposed on
the image in the focal plane, the three-dimensional distribution of the object
can be recognized by moving the focal plane in the depth direction. To obtain
supplemental information for the object, acquiring images from different
angles is helpful for recognizing the spatial distribution of the object more
precisely. Although the image obtained contains blurred images outside the
focus the proposed imaging technique is expected to be useful in MR fast
angiography.
|
| title | author | page |
| Noise Analysis and Noise Suppression with the Wavelet Transform for
Low Contrast Urinary Sediment Images |
Ning-Feng ZENG, Keiji TANIGUCHI, Sadakazu WATANABE, Yutaka NAKANO |
829-840 |
|
Key words : Noise suppression, Low contrast image, Wavelet transform, Local
de-noising factor, Urinary sediment image
|
|
Abstract : This paper proposes a new scheme for noise reduction in low
contrast urinary sediment images (LCUSI). The noise in LCUSI is analyzed and
classified as different types of noise according to their features and source.
First, a noise sample image and the features of the noise are used to reduce
the non-stochastic noise. Second, the wavelet transform (a-trous algorithm) is
used to divide the image into different scales for suppressing the stochastic
noise separately. Then, in order to maintain the sharpness of the edges of
objects, the thresholds in the different scales for filtering noise are
selected by incorporating a local denoising factor which is determined by
fuzzy reasoning. Finally, all the processed scales are combined. This scheme
can not only effectively reduce noise in LCUSI, but also retains the
information of the edges of objects in the image. Our experimental results
show that the performance of this method is superior to that of other methods.
This method is very effective for preprocessing LCUSI.
|