Message
Having a big dream and realizing
it step by step are crucial in the information age, which
is characterized by "change" and brings you a
lot of chances such as achieving innovative technologies,
establishing a breakthrough science, innovating profitable
e-business and implementing sustainable social infrastracture.
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Publications(January 2001 - December 2001)
- H. Hanaizumi, K.Ohmori and T. Nakagawa. "Three Dimensional
Thinning Algorithm and Its Application to Lung Cancers"
JAMIT Frontier 2001 (in Japanese)
Abstract - The helical
CT is a very powerful tool to detect lung cancers. The
helical CT, however, outputs a lot of slice images to
be examined for a patient. Increase of number of images
to be examined may cause miss detection of cancers. On
the other hand, rapid development of multi- slice CT provides
very high resolution 3D images and huge number of images
to be examined. An efficient screening system has been
required for improving the efficiency and the accuracy
of the examination. We consider that multi-temporal proceeding
of 3D lung images, i.e. changes detection between blood
vessel images is one of the solutions to make efficient
screening. Here, we propose a skeletonizing algorithm
for blood vessel images whose shapes are distorted by
breathing. The validity of the proposed algorithm was
confirmed by numerical simulation. The application results
of the algorithm to the actual 3D blood vessel images
were also shown.
- K. Narimatsu, S.Takatani and K.Ohmori. " A Multi-Element
Tonometry Sensor For Noninvasive Measurement of Pulse Wave
Velocity", Frontiers of Medical Electronics and Biological
Engineering, Vol. 11, No. 1, pp45-58 (2001)
Abstract - In the previous
study, the multi-element tonometry sensor based noninvasive
PWV measurement system was evaluated for its frequency
response characteristics, and for its accuracy in pulse
wave propagation time measurement in simulated circulatory
system. Excellent results supported the use of this system
in noninvasive measurement of PWV possibly from the carotid
and femoral arteries. However, its accuracy has not been
validated in the actual physiological system. Since the
noninvasive pulse wave measurement is affected by the
tissue between the sensor and the vessel, hold-down force
applied to position the sensor, and physiological variables
such as heart rate and blood pressure levels, further
study was undertaken to quantify their effects upon pulse
wave, hence PWV measurement. For the animal model, we
used the common carotid artery of female goats whose body
weight was close to average human size(60 Kg). The study
was divided into two groups; in Group I the tonometric
sensor was directly applied to the exposed left common
carotid artery, while in Group II the sensor was applied
over the skin and subcutaneous tissues covering the artery.
As a control measurement, a 1.4 F Millar catheter was
inserted inside the carotid artery at the vicinity of
tonometric measurement site. Also, a 4 F Millar catheter
was inserted through a contra-lateral carotid artery and
its tip was advanced to the root of aorta for measurement
of aortic pressure waveform. Both the Millar and tonometric
measurements were referenced to the aortic waveform for
computation of PWV. First, we changed the hold down forces
of the sensor applied to the artery. Second, systolic
blood pressure levels were changed from 85 to 170 mmHg
by drugs. Third, heart rate was changed from 80 to 145
beats/minute by drugs and a pacemaker. The results showed
an excellent correlation between the tonometric and Millar
measurements with and without skin and subcutaneous tissues.
The correlation coefficients between the Millar and tonometric
methods for PWV measurements were 0.99 with and without
skin and subcutaneous tissues. The bias±}2SD for
the pulse transmission time between the two methods(the
Millar minus tonometric ) were -1.14±}0.76 ms for
the exposed artery, while for the covered artery -0.87±}0.56
ms. These results confirmed that the arterial wall, subcutaneous
tissue and skin do not affect the accuracy of pulse wave
measurements under varying physiological conditions. It
was thus concluded that the multi-element sensor could
be used for effective and accurate noninvasive PWV measurement
in vivo.
- K.Narimatsu, S. Takatani, H. Kanai and K. Ohmori. "Accuracy
of Multi-Element Tonometry Sensor-Based Noninvasive PWV
Measurement System as Evaluated in Animal Model" Journal
of the Japan Society of Medical Eletronics and Biological
Engineering, Vol.39 No.3 (2001) 30-36(in Japanese)
Abstract - A new pulse
wave velocity (PWV) measurement system has been developed
using a novel multi-element tonometry carotid sensor combined
with a heart sound sensor. In this system, PWV is derived
from the time lag between the second heart sound (S2)
obtained from the heart sound sensor and the dicrotic
notch in the carotid pulse waveform, and the physical
distance between the heart and the neck. We assessed the
accuracy of the system in an animal model. The study was
divided into two groups; in Group I the tonometric sensor
was directly applied to the exposed artery, while in Group
II the sensor was applied over the skin and subcutaneous
tissues covering the artery. To examine the fidelity of
the dicrotic notch, the ejection time with the tonometry
sensor was compared with that obtained from the intra-arterial
catheter measurement. The correlation coefficients between
them were 0.99 in both groups. The bias error±}2SD,
defined as the mean of the differences between the tonometry
and the catheter measurements±}the twice the standard
deviation, was 0.13±}1.45 ms in Group I, while in
Group II 0.16±}1.64 ms. These results confirmed that
the arterial wall, subcutaneous tissue and skin did not
affect the accuracy of the dicrotic notch fidelity. The
reproducibility of the system was assessed in 18 human
subjects. The 2SD of intraobserver and interobserver reproducibility
of the S2-carotid PWV measurement were 0.54 and 0.38 m/s,
respectively, demonstrating high reproducibility of the
measurement. From a clinical point of view, the S2-carotid
PWV was compared with the aortic PWV. The bias error±}2SD
between the two measurements was -0.14±}3.24 m/s
with the correlation coefficient being 0.73. Although
the S2-carotid PWV may not replace the aortic PWV directly,
we believe that the S2-carotid PWV with the new system
may become a new clinical parameter for early detection
of cardiovascular disorders such as cerebrovascular diseases.
- K. Ohmori and T. L. Kunii. "Shape Modeling Using
Homotopy" Shape Modeling International '2001 (May),
Genoa Italy (2001) 126-133
Abstract - We introduce
a new method of shape modeling using homotopy and object-oriented
modeling. Homotopy is a kind of topology that gives more
general ideas of preserving invariant properties of geometrical
objects and is further expanded to conceptual objects.
The conventional shape modeling using polygonalization
has serious difficulties in preserving invariant properties,
leading to the necessity of a massive amount of data.
On the other hand, the combination of homotopy and object
oriented modeling, which uses class hierarchy, help preserve
invariant properties of all abstraction levels. We will
explain how our new method will help us preserve invariant
properties, which keeps the amount of data to the minimum
possible level, using an example of a tennis ball rolling
on a slope.
- K. Ohmori, "Cellular Structured Spaces for Multimedia"
Proceedings of The 7th International Conference on Distributed
Multimedia Systems, pp. 171-178, Tamkang University, Taipei,
Taiwan, September 2001.
Abstract - We introduce
new conceptual tools for multimedia. Multimedia, ranging
from traditional media such as newspapers, TVs and movies
to new media such as computers, mobile phones and game
machines, is a leading technology in the information age
and is based on various technologies. Among them, computer
graphics and digital animation are key technologies. These
technologies are based on shape modeling of how objects
are visualized as multimedia. We introduce a new method
of multimedia using homotopy and object-oriented modeling.
Homotopy is a kind of topology that gives more general
ideas of preserving invariant properties of geometrical
objects and is further expanded to conceptual objects.
The conventional shape modeling in multimedia uses polygonalization
and has serious difficulties in preserving invariant properties,
leading to the necessary of a massive amount of data.
On the other hand, the combination of homotopy and object-oriented
modeling, which uses class hierarchy, help preserve invariant
properties at all abstraction levels. We will explain
how our new method will help us preserve invariant properties,
while keeping the amount of data to the minimum possible
level, using an example of a teapot.
- H. Hanaizumi and K.Ohmori. "Three Dimensional Thinning
Algorithm and Its Application" JAMIT Frontier 2002,
Beppu Japan (2002) (in Japanese)
Abstract - In order
to construct a screening system in which multi-temporal
3D helical CT data are registered and shape changes of
vessels during the period are detected, we propose an
algorithm using Homotopy of recognizing vessels and bronchus
in lung. This algorithm is one of region growing algorithms
and we call it as successive region growing (SRG). The
algorithm successively expands cross sections from the
start point to the end of vessels and a skeleton of the
vessel is obtained by tracing gravity centers of each
cross section. Since SRG is very sensitive, it may yield
false branches for a noisy surface. These false branches
are successfully removed by using an index 'significance'
of the branch. In the case of bronchus recognition, terminal
point of its small branch may connect to outer lung in
terms of boxel density and the connection causes miss-recognition
of branches. For avoiding the miss-recognition, SRG automatically
detects the connection and stops itself. In this paper,
we describe the principle and the procedure of SRG. The
application results of SRG to actual multi-temporal 3D
CT images are also shown.
- W. Li and K.Ohmori. "Hierarchical Visualization
of 3-Dimensional Objects Using Cellular Structured Spaces",
Workshop on ITS and Image Processing, Sapporo Japan (2002)
(in Japanese)
Abstract - Three-dimensional
computer graphics is currently visualized on a computer
display, using the technology of polygonization modeling
with a single layer structure. However, characteristic
properties of objects cannot be preserved by a single
layer structure. Therefore, this paper describes how to
build data structure of objects with multiple-layered
structure. Cell structured spaces give means of a cell
model for representing abstract classes of an object,
and are helpful as effective tools for expressing the
abstract model of visualization.
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