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Development of a Virtual Needle Biopsy Simulation System for

the Virtual Prostate

Daisuke Deguchi,1

Kensaku Mori,1

Yoshito Mekada,1

Jun-ichi Hasegawa,2

Jun-ichiro Toriwaki,1*

and

Masanori Noguchi3

1Graduate School of Engineering, Nagoya University, Nagoya, 464-8603 Japan

2School of Computer and Cognitive Sciences, Chukyo University, Toyota, 470-0393 Japan

3School of Medicine, Department of Urology, Kurume University, Kurume, 830-0011 Japan

SUMMARY

This paper discusses the virtual prostate needle bi-

opsy system and the construction of the virtual prostate

model, considering the actual distribution of prostate ab-

normalities. A needle biopsy simulation is performed for

the constructed virtual prostate, and the actual biopsy pro-cedure in the clinical situation is evaluated. The prostate

needle biopsy is a histologic diagnosis procedure in which

a sample is acquired from the prostate tissue by needle

biopsy and is inspected under a microscope. In order to

achieve reliable prostate needle biopsy, it is necessary to

consider systematically and numerically the number of

needles required, and their locations and insertion angles.

For such a purpose, a system is developed in which a virtual

prostate is constructed on a computer and the biopsy pro-

cedure is evaluated quantitatively by performing virtually

the prostate needle biopsy. Furthermore, two different mod-

els are constructed, for the prostate with and without hyper-

trophy, based on the actual statistical distribution data for

prostate abnormalities. Each model is partitioned into the

peripheral zone and the transition zone. The constructed

virtual prostate is input into the virtual needle biopsy simu-

lation system, and three different systematic biopsy proce-

dures actually used at clinical sites, and four different

needle biopsy procedures, are experimentally evaluated.

The experiments show that the insertion angle that maxi-

mizes the hit probability is not always the same as the

insertion angle that maximizes cancer sample acquisition.

It is evident that the proposed method can indicate a biopsy

procedure which realizes a high hit probability with a small

number of needles. 2005 Wiley Periodicals, Inc. Syst

Comp Jpn, 37(1): 93104, 2006; Published online in Wiley

InterScience (www.interscience.wiley.com). DOI

10.1002/scj.20181

Key words: virtual prostate; prostate needle bi-opsy; virtual reality; quantitative evaluation.

1. Introduction

Prostate cancer is a cancer with a relatively low

incidence rate, which is approximately 3.5% in Japan. In

2005 Wiley Periodicals, Inc.

Systems and Computers in Japan, Vol. 37, No. 1, 2006Translated from Denshi Joho Tsushin Gakkai Ronbunshi, Vol. J87-D-II, No. 1, January 2004, pp. 281289

*

Now affiliated with the Faculty of Information Science, Chukyo Univer-sity.

Contract grant sponsors: Parts of this research were supported by a

Grant-In-Aid for Scientific Research from the Ministry of Education, the

21st Century COE program, a Grant-In-Aid for Scientific Research from

the Japan Society for Promotion of Science, and a Grant-In-Aid for Cancer

Research from the Ministry of Health and Welfare of the Japanese Gov-

ernment.

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European countries and the United States, on the other

hand, it accounts for approximately 20% of deaths of males

by cancer [1]. The incidence rate is increasing in Japan due

to the rapidly westernizing lifestyle and the extension of the

life span. In terms of cancer locations, the incidence rate is

higher than those of lung cancer and colon cancer, and the

highest of all urological diseases.

It is now being intensively discussed whether it is

worthwhile to apply prostate cancer examination as a na-

tional project. Several reports have been presented on thevalidity of mass screening for prostate cancer. There still

remain several points to be solved, however, before exami-

nation is performed on the national level, and it is desirable

to establish an efficient examination system [24].

Means of examination for prostate cancer include

PSA (prostate-specific antigen) determination, tactile ex-

amination from the rectum, and ultrasonic tomography.

When an abnormality is noticed, the next step generally is

to perform a prostate needle biopsy. The prostate needle

biopsy is a histologic examination procedure in which a

tissue sample is acquired from the prostate by needle biopsy

and is inspected by using a microscope. It is the only meansof diagnosing prostate cancer.

In recent years, prostate examination by PSA has

been widely applied, and the opportunity to detect prostate

cancer in an early stage is increasing. Thus, an important

issue is how tissue samples can be acquired accurately and

securely from a small pathological site, which cannot be

detected by tactile examination from the rectum. Further-

more, thick 14-gauge needles (diameter approximately 2.1

mm) have conventionally been used in prostate needle

biopsy, which is fairly invasive, and only a limited number

of needles can be used in the biopsy. Recently, thin 18-

gauge biopsy needles (diameter approximately 1.2 mm)

have come into use, and biopsy at six to eight points can be

performed, which promotes safer and more reliable acqui-

sition of samples [5].

At present, systematic biopsy at six points is the most

general procedure. However, it is not always true that the

biopsy needle acquires a pathological sample, and it is

necessary to investigate the biopsy procedure systemati-

cally and numerically in terms of the number of needles,

the locations, and the directions of insertion. It is thus

required to develop a system that can evaluate the biopsy

procedure quantitatively.

In this context, we developed a prostate needle biopsy

simulation system which can perform a virtual prostateneedle biopsy [6, 7]. This prostate needle biopsy simulation

system performs a virtual needle biopsy for a virtual pros-

tate which is constructed from the actual sample. Conse-

quently, the experiment is based on the actual distribution

of abnormalities. However, the pattern of abnormality dis-

tribution that can be obtained is limited due to the limited

number of extracted samples.

Based on the partitioning of the prostate given in

Refs. 811 and the anatomical observations of the prostate

given in Refs. 1217, a virtual prostate model is constructed

considering the incidence rate of abnormalities obtained

from the statistical data. Virtual needle biopsy is applied to

the model. Specifically, the procedure is as follows. The

interior of the prostate is partitioned into the peripheral zone

(PZ) and the transition zone (TZ). The volume ratio of the

PZ and TZ varies according to whether prostate hypertro-

phy is present. Consequently, the prostate model withouthypertrophy (normal model) and the model with hypertro-

phy (hypertrophy model) are constructed. Then, an experi-

ment is performed for a systematic biopsy with 6, 8, and 10

needles, with the needle locations used in the clinical situ-

ation, and for four other different needle locations. The

performances of the biopsy procedure, as dependent on the

needle locations, are compared and evaluated.

In the following, Section 2 describes the virtual nee-

dle biopsy simulation system. Section 3 describes the nor-

mal and hypertrophic models of the prostate which are

proposed in this paper. Section 4 describes each of the

biopsy procedures under consideration. Section 5 presentsexperiments on the constructed model and their results.

Section 6 gives a discussion.

2. Virtual Needle Biopsy Simulation

System

2.1. Virtual needle biopsy simulation

The virtual needle biopsy simulation is composed of

the following four processes:

(a) Definition of the reference plate in which to locate

the virtual biopsy needles

(b) Location of virtual biopsy needles in the reference

plate

(c) Determination of insertion angle of the virtual

biopsy needles

(d) Performance of virtual biopsy

The detailed procedure is as follows. A left-hand coordinate

system is used in the description in this paper, and clock-

wise rotation is defined as positive.

(a) Definition of reference plate

The reference plate in which to locate the virtual

biopsy needle is defined as the rectangular region which

corresponds to the range of needle insertion in a clinical

examination. The plate is determined by specifying three

points (Ltop, Lbot, Rbot) on the plane, as shown in Fig. 1.

Specifically, a plane tangent to the rectal side of the prostate

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is considered. The reference plate is defined so that it is

tangent to the projection of the prostate onto the above

plane, and LbotLtop

agrees with the direction from the cusp

of the prostate to the seminal vesicle (SV). The positive

direction of the normal to the reference plate is defined as

the direction from the rectal side to the prostate.

All biopsy needles are located on this reference plate.

The unit vectors H, V, and N that determine the direction

of the reference plate are defined as follows:

Here denotes the vector product, and |||| denotes the

Euclidean norm of a vector.

(b) Location of virtual biopsy needle

AnMNgrid is defined on the reference plate. An

arbitrary grid point p(i) is selected on the grid and is defined

as the location of the virtual biopsy needle(i) on the refer-

ence plate. The grid point p(i) is defined as follows usingm(1 m


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insertion angles 1(i) and 2

(i). Specifically, d(i) is derived by

the following procedure.

(1) H is defined as the rotation axis, and d0(i) is rotated

by 1(i). Let the obtained unit vector be d1

(i).

(2) H is defined as the rotation axis, and d0(i) is rotated

by 1(i) 90. Let the obtained unit vector be d2

(i).

(3) d2(i) is defined as the new rotation axis, and d1

(i) is

rotated by 2(i). Let the obtained unit vector be d(i).

(d) Virtual needle insertion

The virtual needle insertion is performed on the basis

of the needle insertion parameters of the virtual biopsy

needle(i), which are the location p(i), the insertion direction

vector d(i), the length of sample acquisition from the tip of

the biopsy needleL(i), the radius of the needleR(i), and the

depth of insertion l(i), as shown in Fig. 3. We setL(i)l(i).

The set of voxels S(i) where the tissue sample can be

acquired by the virtual biopsy needle is expressed as fol-

lows. The start location s(i) and the tip location e(i) are

expressed as

Then,

(where denotes the scalar product of vectors). In other

words, the voxels that can be acquired by a virtual needle

insertion are the interior of a cylindrical region with the

segment connecting the start location s(i) and the tip location

e(i) as the center and with radiusR(i).

In S(i) and in the prostate, let the set of abnormal

voxels be A(i). Specifically,A(i) is the set of voxels which

are classified as abnormal in the virtual prostate within

S(i), satisfying Eq. (4). In practice, tissue other than the

prostate may be sampled in the virtual biopsy needle. In thissystem, such a region is classified as normal.

2.2. Quantitative evaluation of needle biopsy

procedure

In needle biopsy, a determination is made for each

inserted biopsy needle whether the abnormal sample has

been acquired, and if it has been acquired, the volume of

the acquired tissue is calculated. When a virtual biopsy

needle acquires an abnormality, it is called a hit. It is clinical

knowledge that the physician can detect the disease if at

least 1% of the tissue volume acquired by a biopsy needleis abnormal. In other words, the following decision formula

is used:

When at least one of the biopsy needles in the needle biopsy

procedure is a hit, the needle biopsy procedure is called a

hit.

The total volume of the abnormal sample acquired by

the needle biopsy procedure is defined as follows, using the

set of abnormal voxelsA(i) acquired by each virtual biopsyneedle, the volume of a voxel, and the total number Nof

virtual biopsy needles inserted in the needle biopsy proce-

dure:

Here, || denotes the number of pixels contained in the set.

Based on the above definition, the biopsy procedure is

evaluated quantitatively below by using the hit probability

and the average cancer acquisition volume.

2.2.1. Hit probability

The hit ratio in the case of virtual needle biopsy is

defined as the hit probability of the needle biopsy proce-

dure. It is calculated as follows:

hit probability[%] =number of hit cases

total number of cases 100 (7)

(3)

Fig. 3. Parameter representation of the virtual biopsy

needle.

(2)

(4)

(5)

(6)

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2.2.2. Average cancer acquisition volume

The abnormal volume per sample acquired by the

needle biopsy procedure is defined as the average cancer

acquisition volume. It is calculated as follows:

average canceracquisition volume

=total volume of acquired cancer

totalnumber ofcases (8)

The above volume divided by the number of biopsy needles

is the average volume of the cancer tissue that can beacquired by a biopsy needle.

3. Virtual Prostate Model

It is impossible to partition the prostate into PZ and

TZ regions by using only the three-dimensional X-ray CT

density values. Consequently, a schematic figure of the

prostate is constructed as in Fig. 4, based on the partition

inside the prostate [811] and the anatomical observations

inside the prostate [1217]. Then, the interior region of the

prostate is partitioned.

As shown in Table 1, the abnormality incidence ratediffers between the PZ and TZ regions in the prostate.

Consequently, the volume ratio also differs. The virtual

prostate model is constructed so that the volume ratio and

the abnormality incidence rate shown in Table 1 are real-

ized. It should also be noted that the ratio of the PZ and TZ

regions in the prostate differs between prostates with and

without hypertrophy. Consequently, two virtual prostate

models are constructed, namely, the prostate model for

hypertrophy (hypertrophy model) and the prostate model

without hypertrophy (normal model). Specifically, the

shape of the prostate is assumed to be an ellipsoid, and the

inside is partitioned [18, 19].

As the normal model, each cross section of the actu-ally excised three-dimensional X-ray CT image is parti-

tioned into PZ and TZ regions manually, based on the

schematic figure as shown in Fig. 4. Figure 5(a) shows the

cross sections of the constructed virtual prostate. Panels (b),

(c), and (d) are the three-dimensional representations. The

shape of the hypertrophy model is assumed to be an ellip-

soid. As shown in panel (e), the region within a certain

distance from the rectal side surface of the prostate is

defined as the PZ region. As in the normal model, panels

(f), (g), and (h) give a three-dimensional representation of

the hypertrophy model.

Table 2 shows the specifications for the virtual pros-tate, the constructed normal model, and the hypertrophy

model. As is evident from the table, the constructed virtual

prostate satisfies the volume ratio conditions in Table 1. The

shapes of the PZ and TZ regions were examined by the

physician, and were judged to be adequate.

4. Needle Biopsy Procedure

4.1. Systematic biopsy

The systematic biopsy focuses systematically on the

PZ, which is the most common site of prostate cancer, as

shown in panels (a), (b), and (c) of Fig. 6. By systematically

applying the biopsy, a detection rate which is twice that of

directed biopsy focusing on the hypoechoic region in ultra-

Fig. 4. Definition of PZ and TZ inside the prostate.

Table 1. Volume ratio of the PZ, TZ, and CZ inside the prostate, and probabilities of the incidence of prostate cancer

within each region

PartitionPZ

(peripheral region)

TZ

(transition region)

CZ

(central region)

Ref. 9 Volume ratio

Cancer incidence rate

6570%

68%

510%

24%

25%

8%Ref. 12 Volume ratio


70%

70%~

5%

20%

25%

510%

Proposal Normal model

2030 ml

Volume ratio


60%

75%

40%

25%

Hypertrophy model

above 50 ml

Volume ratio


10%

75%

90%

25%

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sonic tomography is realized [5]. The 8-needle systematic

biopsy is the needle location method in which 2 needles for

the extensive protocol, directed to the deeper side of the

prostate as seen from the rectal side, are added to the

6-needle arrangement shown in Fig. 6(a). The 10-needle

systematic biopsy consists of the addition of 4 extensive

protocols to the PZ side.

4.2. New biopsy needle locations

[Needle placement 1] We wish to cover the 10-needle

systematic biopsy locations [4 needles added as in Fig. 6(c)

to the 6-needle systematic biopsy arrangement shown in

Fig. 6(a)] with 6 needles located at the vertices of a normal

hexagon.

[Needle placement 2] The needles are located at the

vertices of the normal hexagon, as in placement 1, and the

top two needles to be inserted into the cusp of the prostate

[top two needles in Fig. 6(e)] are shifted toward the center

of the prostate.

[Needle placement 3] We wish to cover the 8-needle

biopsy placement [2 needles added as shown in Fig. 6(b) tothe 6-needle systematic biopsy placement shown in Fig.

6(a)], with the 6 needles being arranged in an H pattern.

[Needle placement 4] A needle directed toward the

central region is added to needle placement 1, so that the

needles are located at the vertices of a normal pentagon and

also at the center of gravity.

5. Experiment

The prostate needle biopsy simulation system de-

scribed in this paper was implemented on a computer andwas applied to the proposed normal and hypertrophy mod-

els. Based on the data in Table 1, the incidence rates of

abnormalities in the constructed models were set as 75%

for the PZ region and 25% for the TZ region. Four thousand

virtual prostate samples were constructed, generating one

Fig. 5. Created virtual prostate model. (a) shows slices

of the regular size prostate model, and its 3D shapes are

shown in (b), (c), and (d). Slices of the prostate model of

hypertrophy are shown in (e), and its 3D shapes are

presented in (f), (g), and (h).

Table 2. Acquisition parameters of each prostate model

PZ

(peripheral region)

TZ

(transition region)PZ+TZ

Normal model Number of pixels 574631 392211 966842

Volume [ml] 14.5 9.9 24.4

Volume ratio 59% 41% 100%

Hypertrophy model Number of pixels 205945 1848728 2054673

Volume [ml] 5.2 46.5 51.7

Volume ratio 10% 90% 100%

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spherical abnormality each. We set the volume of the gen-

erated abnormality in accordance with a normal distribution

with a mean of 2 ml and a standard deviation of 1 ml.

The reference plate on which the virtual biopsy nee-

dles were placed was defined as a rectangle in external

contact with the rectal side of the prostate, as in Fig. 1. The

parameters of the virtual biopsy needle to be inserted were

chosen as follows, based on data on clinically used biopsy

needles. The length of tissue sample acquisition wasL = 15

mm from the tip of the biopsy needle. The depth of needleinsertion was l = 15 mm (l = 20 mm for only the extensive

protocols in the eight-needle systematic biopsy). The radius

of the needle wasR = 0.6 mm. The needle insertion angle

was 30 1 50 and 40 2 40 (deg).

A rotation of1 > 0 was defined as the rotation from

the normal direction of the reference plate to the SV region

side. Rotation by 2 was defined symmetrically with respect

to the left and right from the reference plate. A needle

rotation of2 < 0 was from the direction of the center of

the reference plate, and a rotation of2 0 (deg) was toward

the outer side of the reference plate. The computer used in

the experiment was a Dual AthlonMP 1800

+

, Win-dows2000.

6. Discussion

Figures 7 and 8 show the average hit probability

distributions when 1 and 2 are varied in the normal model

and the hypertrophy model, respectively. As is evident from

the figures, the obtained hit probability distribution differs

for the normal and hypertrophy models. The reason for the

difference is that the volume percentage of the PZ region,

where the cancer incidence is high, differs greatly in the

normal and the hypertrophy models. In particular, the hit

probability does not change much in the hypertrophy model

if the insertion angle is varied. This is attributed to the small

volume of the PZ region, where the cancer incidence rate is

high.

Experiments were performed for the seven different

needle biopsy procedures shown in Fig. 6. It is evident that

the 10-needle systematic biopsy and needle placement 1

give higher hit probabilities in the range of this experiment

(Table 3). In particular, needle placement 1 gives a higher

value than the 8-needle systematic biopsy, even though only

6 biopsy needles are used. It is clear from Table 4, on the

other hand, that a smaller volume of cancer samples can beacquired by needle placement 1 than by the other place-

ments.

Fig. 6. Locations of virtual needles inside biopsy plane for each biopsy method. (a), (b), and (c) show systematic 6, 8, and

10 biopsy methods, and (d), (e), (f), and (g) show biopsy method 1, 2, 3, and 4, respectively.

Fig. 7. For the regular size prostate model, the change of average hit probabilities (AHP) as 1 and 2 change. (a), (b), and

(c) show the results of systematic 6, 8, and 10 biopsy methods, respectively. (d) shows the results of biopsy method 1.

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Thus, by using the proposed system, a needle place-

ment that can achieve a high cancer detection rate with

fewer insertion needles can be sought, considering the

cancer incidence rate distribution and the size of the pros-

tate. Furthermore, the relation between the hit probability

and the acquired cancer sample volume can be investigatednumerically. Even if it is difficult to perform a procedure in

a clinical situation, an a priori evaluation can be made.

In the experiments with the 4000 cases of virtual

prostate that were constructed, 7 hours of calculation were

required per virtual biopsy needle when the angles were

varied as 30 1 50 and 40 2 40 (deg). This

corresponds to virtual needle insertion for approximately

2.6 107

patterns, which is a tremendous amount of com-putation. When simulations are performed for various pro-

cedures to be matched to individual patients, the

Fig. 8. For the hypertrophic prostate model, the change of average hit probabilities (AHP) as 1 and 2 change. (a), (b), and

(c) show the results of systematic 6, 8, and 10 biopsy methods, respectively. (d) shows the results of biopsy method 1.

Table 3. For the regular size prostate model and the hypertrophic prostate model, mean, standard deviation,

and maximum of the average hit probabilities when 1 and 2 change

(a) Regular size prostate model

Average

[%]

Standard

deviation

Maximum

[%](1, 2)

6-needle systematic biopsy 51.4 8.45 66.9 (2, 7)



Needle location 1 53.8 9.92 71.4 (4, 4)

Needle location 2 52.2 8.71 68.1 (14, 1)

Needle location 3 53.0 7.52 66.2 (2, 5)

Needle location 4 52.3 9.76 69.0 (8, 3)

(b) Hypertrophic prostate model

Average

[%]

Standard

deviation

Maximum

[%](1, 2)




Needle location 1 56.8 3.87 61.8 (50, 3)

Needle location 2 50.5 4.26 60.7 (50, 1)

Needle location 3 51.7 3.48 60.6 (47, 40)

Needle location 4 51.7 3.39 59.1 (49, 30)

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computation time will be a serious problem. Speed im-

provement of the proposed system should be investigated

in the future.

7. Conclusions

In this study, the virtual prostate model was con-

structed, based on anatomical knowledge and statistical

data on the abnormality distributions. A prostate needle

biopsy simulation system was developed on the basis of the

model. Systematic biopsy procedures used in clinical situ-

ation, together with four other needle placement proce-

dures, were considered. A quantitative evaluation is

performed in terms of the hit probability and the average

cancer sample acquisition volume.

It was shown that by using the prostate needle biopsy

simulation system proposed in this paper, large-scale ex-periments that are impossible in an actual clinical situation

can be performed, allowing the effectiveness of parameters

such as the number of biopsy needles and the insertion angle

to be investigated systematically. Furthermore, by con-

structing two models with and without prostate hypertro-

phy, a simulation more closely approximating a real

prostate can be achieved. Experiments show that the needle

insertion angle that maximizes the hit probability is not

always the same as the insertion angle that maximizes the

acquired volume. It is verified that there exists a needle

biopsy procedure that can achieve a high hit probability

with fewer needles.

Problems remaining for the future include evaluation

experiments using a large number of samples, the search for

an optimal biopsy procedure using the proposed system,

speed improvement of the proposed system, and evaluation

by physicians.

Acknowledgments. The authors are grateful for

continued discussions with members of the Toriwaki and

Suenaga Laboratories at Nagoya University. They espe-

cially acknowledge the assistance provided in most of the

experiments by Mr. S. Kodama of the Toriwaki Laboratory

(now of the Graduate School, University of Tokyo). Parts

of this research were supported by a Grant-In-Aid for

Scientific Research from the Ministry of Education, the

21st Century COE program, a Grant-In-Aid for Scientific

Research from the Japan Society for Promotion of Science,

and a Grant-In-Aid for Cancer Research from the Ministry

of Health and Welfare of the Japanese Government.

Table 4. For the regular size prostate model and the hypertrophic prostate model, mean,

standard deviation, and maximum of the average cancer volume acquired by a biopsy

method when 1 and 2 change

(a) Regular size prostate model

Average

[mm3]

Standard

deviation

Maximum

[mm3]

(1, 2)




Needle location 1 4.64 1.24 6.11 (0, 24)

Needle location 2 5.06 1.17 6.20 (5, 39)

Needle location 3 5.21 0.69 6.19 (6, 40)

Needle location 4 4.82 1.23 6.20 (4, 29)

(b) Hypertrophic prostate model(1, 2)

Average

[mm3]

Standard

deviation

Maximum

[mm3]

(1, 2)




Needle location 1 4.48 0.44 5.50 (50, 40)

Needle location 2 4.24 0.42 5.39 (50, 22)

Needle location 3 4.34 0.34 5.55 (50, 40)

Needle location 4 4.10 0.40 5.11 (50, 40)

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AUTHORS

Daisuke Deguchi (student member) received a B.S. degree in 2001 from the Faculty of Engineering at Nagoya University

and is now an M.E. degree candidate. He is engaged in development of flexible endoscope navigation system and prostate needle

biopsy simulation system.

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AUTHORS (continued) (from left to right)

Kensaku Mori (member) received his B.S. degree in electronics engineering, M.S. degree in information engineering,

and Ph.D. degree in information engineering from Nagoya University in 1992, 1994, and 1996. He was a research fellow of the

Japanese Society for the Promotion of Science (JSPS) from 1994 to 1997, a research associate in the Department of

Computational Science and Engineering at Nagoya University from 1997 to 2000, and an assistant professor in 2000. He became

an associate professor at the Research Center for Advanced Waste and Emission Management of Nagoya University in 2001.

He was a visiting associate professor in the Department of Neurosurgery at Stanford University from 2001 to 2002. He is

currently an associate professor in the Graduate School of Information Science, Nagoya University. His current research interests

include three-dimensional image processing, computer graphics, virtual reality and their applications to medical image. He

received an award for the encouragement of research from the Japanese Society of Medical Imaging Technology in 1995, a

paper award from the Japanese Society of Biomedical Engineering in 1997, the Niwa Award from the Niwa MemorialFoundation in 1998, and a Certificate of Merit award from the Radiological Society of North America in 2004. He is a member

of IEICE, IEEE, Japanese Society of Biomedical Engineering, and Japanese Society of Medical Imaging Technology.

Yoshito Mekada (member) received a B.S. degree in 1991 from the Department of Information, Faculty of Engineering,

Nagoya University, completed the second half of the doctoral program in 1996, and became a research associate in the

Department of Information Engineering at Utsunomiya University. He was appointed an associate professor of information

engineering in 2001 at the Graduate School of Engineering, and an associate professor of media science in 2003 at the Graduate

School of Information Science, Nagoya University. He moved to the School of Life System Science and Technology at Chukyo

University as a professor in 2004. He is engaged in development of image processing and pattern recognition technology, and

in research on their applications to medical image analysis. He holds a D.Eng. degree, and is a member of the Japan Medical

Image Engineering Society, Computer-Assisted Diagnostics Society, IEEE.

Jun-ichi Hasegawa (member) received his B.S. degree in electrical engineering and M.S. and Ph.D. degrees in

information engineering from Nagoya University in 1974, 1976, and 1979. He was a research associate and a lecturer with the

Faculty of Engineering from 1979 to 1987. He moved to the School of Liberal Arts at Chukyo University as an associate professor

in 1987, and became a professor in the School of Computer and Cognitive Sciences in 1992. He is currently a professor and a

dean of the School of Life System Science and Technology. His research interests are in the area of pattern recognition, image

understanding, and their applications to medicine and sports. He is a member of IPSJ, JSAI, JSMEBE (currently JSMBE),

JAMIT, CADM, JSSF, and IEEE CS.

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AUTHORS (continued) (from left to right)

Jun-ichiro Toriwaki (member) received a B.S. degree in 1962 from the Department of Electronic Engineering at Nagoya

University and completed the doctoral program in 1967. After serving as a research associate and an associate professor in the

Faculty of Engineering, he became an associate professor at the Computer Center in 1974. He was appointed a professor at

Toyohashi University of Technology in 1980. He moved to the Faculty of Engineering (later Faculty of Information Engineering,

Graduate School of Engineering) at Nagoya University in 1983, and retired in 2003 under the age limit. Since then, he has been

a professor at Chukyo University and professor emeritus at Nagoya University. He has been engaged in research on pattern

recognition, image processing, graphics, and their applications to medical information. Recently he has been focusing on

three-dimensional image processing, computer surgery, computer-assisted diagnosis, and virtual endoscopy. He is the author

ofDigital Image Processing for Image Understanding I, II(Shokodo), Three-Dimensional Digital Image Processing(Shokodo),

Recognition Engineering (Corona Company), and other books. He is a member of the Information Processing Society,

Computer-Assisted Image Diagnostics Society, and IEEE.

Masanori Noguchi received an M.D. degree in 1980 from Kurume University School of Medicine. He has been an

associate professor in the Department of Urology since 2003. He was a visiting researcher in the Department of Urology at

Stanford University from 1998 to 2000. He is a member of the Japanese Urological Association, Japan Society of Clinical

Oncology, Japan Cancer Society, Japanese Society of Endourology and ESWL, European Urological Association, and American

Urological Association.

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