ORIGINAL COMMUNICATION

Collaborative Learning Using Internet2 and RemoteCollections of Stereo Dissection Images

PARVATI DEV,1* SAKTI SRIVASTAVA,1 AND STEVEN SENGER2

1Stanford University Medical Media and Information Technologies (SUMMIT), Stanford University School of Medicine,Stanford, California

2Department of Computer Science, University of Wisconsin-La Crosse, La Crosse, Wisconsin

We have investigated collaborative learning of anatomy over Internet2, using an applica-tion called remote stereo viewer (RSV). This application offers a unique method of teach-ing anatomy, using high-resolution stereoscopic images, in a client–server architecture.Rotated sequences of stereo image pairs were produced by volumetric rendering of theVisible female and by dissecting and photographing a cadaveric hand. A client–serverapplication (RSV) was created to provide access to these image sets, using a highly inter-active interface. The RSV system was used to provide a ‘‘virtual anatomy’’ session for stu-dents in the Stanford Medical School Gross Anatomy course. The RSV application allowsboth independent and collaborative modes of viewing. The most appealing aspects of theRSV application were the capacity for stereoscopic viewing and the potential to access thecontent remotely within a flexible temporal framework. The RSV technology, used overInternet2, thus serves as an effective complement to traditional methods of teaching grossanatomy. Clin. Anat. 19:275–283, 2006. VVC 2006 Wiley-Liss, Inc.

Key words: medical education; gross anatomy; stereoscopic images; distancelearning; internet2

INTRODUCTION

The Visible Human Project (Spitzer et al., 1996)

made a very large collection of digital images avail-

able for human anatomy (Ackerman, 1999). This rich

data set has been used subsequently to create

numerous learning resources (Hoffman et al., 1997;

Schubert et al., 1997; Jastrow and Vollrath, 2002).

Other projects have added resources, such as the

Visible Korean Human (Park et al., 2005) and LUCY

2 (Heinrichs et al., 2004).

We have used the availability of such digital

image collections to begin the creation of a network-

ed resource of digital anatomy images for teaching

and learning (Dev and Senger, 2005). In particular,

we are investigating the advantages and limitations

of using the Internet as a complementary approach

to traditional cadaver-based teaching.

This article describes our experience in designing,

implementing, and evaluating a unique method of

teaching anatomy, using high-resolution stereoscopic

images, in a client–server architecture. This work

was done as a demonstration project for the National

Library of Medicine under its Next Generation

Internet initiative (http://www.ngi.gov). The NGI

initiative seeks to demonstrate the need for and

define the characteristics of the network technology

required to support innovative biomedical applica-

*Correspondence to: Parvati Dev, PhD, Stanford University

Medical Media and Information Technologies (SUMMIT), Stan-

ford University School of Medicine, 251 Campus Drive, MSOB

Room 240, Stanford, CA 94305-5466, USA.

E-mail: parvati.dev@stanford.edu

Grant sponsor: NLM/NIH; Grant number: 185N034.

Received 28 March 2005; Revised 12 October 2005; Accepted 3

November 2005

Published online 27 February 2006 in Wiley InterScience (www.

interscience.wiley.com). DOI 10.1002/ca.20313

VVC 2006 Wiley-Liss, Inc.

Clinical Anatomy 19:275–283 (2006)

tions. It envisions a secure, high-bandwidth,1 low-la-

tency network for the biomedical research community.

MATERIALS AND METHODS

Creating an Array of Images for Stereo Viewing

and Interaction

We created anatomy image data sets with various

dimensions of interactivity either by rendering 2-D

views of a 3-D volume of crosssectional data or by

photographing rotated views of a dissected specimen.

For rotational viewing and interaction, we acquire or

create a series of rotated views of the anatomy at 58intervals. The data volume or the dissected specimen

may also be photographed at different tipping angles

followed by rotation, as mentioned earlier. The result

is a 2-D array of images with combinations of differ-

ent rotation and tip angles. Additional dimensions of

interactivity include changing transparency and layers

of dissection.

Visible Human data was processed to generate a

series of sequentially rotated images, created at

intervals of 58. Seventy-two images were required to

obtain 3608 of rotation (72 3 5 ¼ 3608). Figure 1

shows five representative frames, acquired at inter-

vals of 158. The frames were originally rendered at a

resolution of 1,024 3 1,024 pixels, compressed for

transmission using a JPEG compression algorithm,

and displayed at the user-desired resolution, typi-

cally 768 3 768. These images were rendered from

the Visible Female CT data to show bone, muscle,

and skin, at increasing levels of transparency, using

segmentation and rendering software developed by

one of us (Senger, 1999). We have also generated

rotation series of the Stanford Visible Female and

other crosssectional data, using commercially avail-

able software (Amira and Volume Graphics).

The image data were stored on server computers

and organized for rapid retrieval. Images are stored

as compressed JPEG images (�200 kB), and are

transported to the client on demand, using a custom

protocol written over the unreliable datagram proto-

col layer, to reduce transmission overhead compared

to the more common TCP/IP protocol. The trans-

port rate was configured to be equal to the JPEG

decompression rate of the client, allowing the client

to interleave receipt and decompression of data.

Acquisition of Stereo Images of a

Dissected Specimen

A fresh cadaveric hand (amputated at mid-fore-

arm) was obtained from the Cadaver Donor Program

at Stanford University School of Medicine. The

hand was mounted on a PiXiTM mechanical turnta-

ble (Kaidan Corp., Feasterville, PA) using a custom-

designed central mounting post, and the entire con-

struct was inverted. Images were taken with a Kodak

520C digital camera with a resolution of 1,764 31,160 pixels. The turntable was rotated through

3608, in steps of 58, to produce a set of 72 images.

Background color, adequate lighting, camera shutter,

and aperture settings were adjusted to produce opti-

mum photographs.

The hand was then removed from the turntable

and dissected superficially. As the hand was re-

mounted, Kirschner guide wires through the radius

and ulna served as landmarks to standardize the hand

position relative to the first set of images. An addi-

tional set of 72 images at this progressively deeper

layer of dissection was then photographed. This pro-

cedure of dissection and photography was repeated

until seven sets of images were produced at increas-

ing depths of dissection. The last set consisted exclu-

sively of the deep layers of muscle of the hand. Fig-

ure 2 shows several representative ‘‘frames’’ from one

dissection level of this data array of 504 images.

The hand dissection data had two dimensions of

interaction: rotation around the long axis of the

hand and dissection depth to expose successive

layers of tissue. At each dissection layer, there are

72 images separated by 58 rotation, allowing one

complete rotation of the hand. Seven such dissec-

tion layers were photographed. Conceptually, this

array of images is organized in the computer as a

stack of seven rings, or a colosseum, so that the

learner traverses around the hand by moving around

a ring, and changes the depth by moving between

rings (Fig. 3).

Fig. 3. A conceptual illustration of the organization of the

images as a ‘‘colosseum.’’ Each floor of the colosseum corresponds

to a layer of the dissection. Traversal around the colosseum corre-

sponds to viewing rotated views at a particular dissection layer. One

such traversal is depicted in the image. The user begins at a skin

view, dissects one layer, rotates the hand through 16 different views

(corresponding to 808 of rotation), and then dissects further to layer

six (the superficial muscles), and finally rotates backward through

258 or five views. Adjacent images at one level are 58 apart, and

correspond to a stereo pair. [Color figure can be viewed in the

online issue, which is available at www.interscience.wiley.com.]

1Bandwidth refers to the amount of information, measured in

bits, which can be transmitted per time unit (usually seconds).

Latency refers to the amount of time that it takes for bits to get

from the source to the destination. Latency ranges from less than

1 msec in local area networks up to a couple of 100 msec for

overseas links via Internet2.

276 Dev et al.

Figure 3.

Fig. 2. Selected views from a 3608 revolution around a hand at multiple stages of dissection.

[Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

Fig. 1. Five representative frames from a sequence of rotated images rendered from CT slices of

the Visible Human female. [Color figure can be viewed in the online issue, which is available at

www.interscience.wiley.com.]

Technology to Support Viewing of Remote

Stereo Images

Stereo images were viewed on an appropriately

configured computer and monitor. The teacher and

students used similarly configured workstations. Each

workstation (cost about $1,200) consisted of a conven-

tional Windows computer (700 MHz Pentium3 pro-

cessor, 256 MB RAM, Windows NT) (Dell, Inc.,

Round Rock, Texas) augmented with a specialized

graphics card (Oxygen GVX1, 3dlabs, Milpitas, Cali-

fornia). Multiple people could view the screen, each

wearing specialized glasses that were automatically

controlled to alternate between left and right eye

vision. A NuVision stereo enabler unit (MacNaugh-

ton, Inc., Beaverton, Oregon) was connected to the

computer to control the glasses. Video conferencing

software (NetMeeting, Microsoft Corporation, Red-

mond, Washington) was used for communication

between workstations. Standard telephone lines were

used as audio channels to facilitate communication

between the students and the instructor. In our more

recent configurations, we use computers with a

2 GHz Pentium4 processor, 512 MB RAM, Windows

2000, or Windows XP operating system, and with

graphics cards ranging from Oxygen GVX1 to the

Wildcat4 (all graphics cards from Nvidia, Santa Clara,

California or 3dlabs, Milpitas, California).

The image database resided on SGI 3200 servers

(Silicon Graphics Inc., Mountain View, California),

on the IRIX unix operating system, locally at the

SUMMIT laboratory at Stanford, and remotely at

the Visualization Laboratory at University of Wiscon-

sin, La Crosse. The image database was accessed by

the students and teacher through a password-pro-

tected website. Each workstation accessed the Inter-

net through a 100-Mbps network interface card.

A Windows NT-based client software application,

the remote stereo viewer (RSV), developed by us for

this purpose, was created to provide access to the

hand and other similar data sets. Simple interaction

using the computer mouse controlled the rotated

view. Left/right mouse motion rotated the image by

shifting through consecutive images within each

rotational set. Vertical mouse motion shifted through

the successive layers of dissection. The client soft-

ware, on the learner’s computer, translates the

mouse motion into appropriate image requests to the

server. The server transmits each requested JPEG

image to the client for display. Adjacent images, sep-

arated by 58, are viewed simultaneously, producing a

stereo effect. A 3-D pointer, which approximates the

appropriate depth of anatomy at that point, was

developed for pointing out anatomical structures.

Technology to Support Video Conferencing

For our initial teaching session, with the complete

first year anatomy class, in 2001, we used a widely

available video conference program, NetMeeting,

with an inexpensive web camera, microphone, and

speaker at each client station. The video image

allowed the teacher to recognize the students in

each group, but was too small to support interaction

based on ‘‘body language.’’ The audio communica-

tion was acceptable. In subsequent teaching sessions,

we have utilized additional systems. We currently

use the open source, multisite, Windows-based,

video conference system, Access Grid, or its com-

mercial instance, supplied by Insors Corp. (inSORS

Integrated Communications, Inc., Chicago, Illinois).

Successful performance of the Access Grid for multi-

ple simultaneous users required a high bandwidth

available on Internet2.

Technology to Support Collaborative Learning

Three technologies were provided to support col-

laborative learning. First, video and audio conferenc-

ing allowed students (and the teacher) to discuss and

ask questions. Second, any learner could become the

‘‘leader’’ in selecting the image to be viewed and

have all other workstations ‘‘follow’’ automatically.

Third, the leader could control the 3-D pointer that

was visible on all follower workstations.

An important aspect of the collaboration technol-

ogy was that it allowed both independent and collab-

orative modes of viewing. In the collaborative view-

ing mode, clients had simultaneous access to the

server and hence the same set of images. One client

controls the image and dissection layer viewed,

while the others observed. Control of the image ori-

entation and pointer position can be easily shared

among clients, thereby creating a ‘‘virtual classroom,’’

in which anyone can lead the others through a set of

images. Assuming or relinquishing control is a simple

two-click process. Any learner could break off collab-

oration by choosing to leave the ‘‘class’’ and to have

independent, personal control of the image viewed.

A subtle aspect of the collaborative capability was

that, if the leader chose to move slowly through an

image sequence, a follower could change their view

locally and yet be brought back to the group view

whenever the leader moved to the next image.

System Configuration for Virtual Classroom

A typical configuration is summarized in Figure 4.

The teacher used a workstation configured for stereo

viewing (Fig. 4a). The image of anatomy is presented

in stereo. The emitter device on top of the monitor

278 Dev et al.

communicates with the specialized glasses, synchroniz-

ing the viewing eye with the display of the left or right

eye image. In Figure 4b, a small group of students is

at a similar workstation in a different building. They

also view the image in stereo. Both the teacher and

the students can control the image rotation independ-

ently. Figure 4c shows the teacher’s view of the stu-

dent groups. This is displayed to the teacher on a sec-

ond monitor. In this study, the students hear the

teacher but did not see him. In subsequent configura-

tions, the students were able to see and hear both the

teacher and the other student groups.

The three client workstations were used by stu-

dent groups in the Stanford University School of

Medicine Anatomy’s computer facility and a fourth

client was available at SUMMIT in a nearby build-

ing for use by the teacher.

A similar configuration, with only two worksta-

tions, was used when one teacher was instructing

another teacher, at a remote campus, in the use of

this new teaching tool. We tested various configura-

tions with multiple clients and different servers.

Use of Internet2

Interactive retrieval of a sequence of images results

in a transmission of bursts of large quantities of data.

(Typical burst bandwidth for our application was 70

Mbps). The commercial Internet does not support

individual use of such a high bandwidth, and results

in jerky displays and dropped images. We used Inter-

net2 (www.internet2.edu), a research and education

network, that is available to member universities

(Fig. 5). Internet2 typically supports ‘‘gigabit connec-

tivity’’ (1,000 Mbps bandwidth) to universities. It has

additional features, such as extended addressing and

security, which we did not use. However, we did use

the ‘‘multicast’’ feature that allowed the 3-D pointer

movement at one workstation to be displayed simul-

taneously at all workstations, and thus supporting col-

laborative discussion between users at different work-

stations at different locations.

Evaluation Instruments

We were interested in the performance of this

application over Internet2, in the students’ reaction

to this learning tool, and in user perception of its

utility as the performance of the network was

degraded. We used survey questionnaires, network

traffic measurement tools, and a 5-point perceptual

scale to assess user response.

Student Recruitment

The study was embedded in the required curricu-

lum for Human Gross Anatomy for first year medical

students. Of 86 first year medical students, 74 stu-

dents participated in the study, and completed the

questionnaire. A 20-min supplemental lesson on

hand anatomy was created and deployed via RSV.

This ‘‘virtual hand anatomy’’ session was held within

1 week of the students’ traditional lecture and labo-

ratory dissection session. Multiple 20-min sessions

with the same faculty member were conducted with

six or seven students each time over a 2-day period.

Sessions were typically about 20 min in length and

were divided into three parts. The first 2 min were

devoted to technological orientation, followed by

about 10 min of didactic, structured presentation by

Dr. Srivastava, one of the regular anatomy faculty.

During the last half of the session, control of hand

and pointer positions was transferred among students

in a more collaborative, open-ended manner. Quali-

tative feedback in the form of questionnaires was

collected from all students immediately after their

RSV session.

RESULTS

Student Response to Collaborative Learning

Using Stereo Images

Of all respondents, 93% professed a computer ex-

perience level of ‘‘moderate’’ or above (Table 1).

Over 86% of the students found the sessions ‘‘help-

ful’’ or ‘‘very helpful.’’ Students stated that they

would use the simulation for help in reviewing anat-

omy (89%), in a self-study mode (76%), and as part

of a collaborative session (39%).

The most appealing aspects of the RSV were the

capacity for stereoscopic viewing (89%) and the

potential to access the content remotely for review

within a flexible temporal framework (89%). Numer-

ous students requested access to other parts of the

body in a similar stereo format. Additional features

requested included image labels, an image-based

quiz, and availability of the program on the Macin-

tosh computer. A deterrent for home use was the

need for special equipment, such as the advanced

graphics card and the stereo glasses. Some found the

stereo viewing experience uncomfortable.

At the end of the quarter, the students completed

an evaluation of the course, which included some

questions about their stereo viewing lesson. The stu-

dents ranked dissection as the most useful learning

tool. Stereo images being ranked at the bottom, with

the stated reason that very few stereo images were

279Collaborative Learning Using Internet2

Fig. 4. A typical configuration for a ‘‘virtual classroom’’ session. a: The teacher uses a workstation

configured for stereo viewing. b: A group of students at a similar workstation in a different building. They

also view the image in stereo. c: A second monitor lets the teacher view all the three student groups.

[Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

Fig. 5. Network configuration to support access to

remotely stored RSV images and to support simultaneous

use of videoconferencing. [Color figure can be viewed in

the online issue, which is available at www.interscience.

wiley.com.]

provided (only hand dissection images were made

available). On the other hand, they ranked stereo

images as the highest among resources that they

wished to see increased.

Network Performance of the Application

The performance of the RSV application was also

measured during these interactive sessions. Trans-

port bursts of between 30 and 40 Mbps between the

servers (either at Stanford or Wisconsin) and the

classrooms were typical. When the Stanford server

was being used, the traffic flowed through the cam-

pus network. The backbone of this network provides

bandwidths in the order of gigabits and latencies of

less than 1 msec. When the server at Wisconsin was

being used, however, the network capabilities were

quite different: Stanford’s connection to the Inter-

net2 had a bandwidth limited to 622 Mbps in the

early experiments, and the delay between Stanford

and Wisconsin-LaCrosse is about 60 msec round trip.

The time between the learner’s query (mouse click)

and image retrieval and display was usually �7 msec

for images stored on the local Stanford server, and

<100 msec when accessing images stored at the Uni-

versity of Wisconsin. This delay is within the

bounds of satisfactory system performance. Table 2

shows the measured requirements for the user to

perceive a satisfactory performance. This perform-

ance was usually achieved even with the server at a

remote location.

Perceptual Response to Network Degrada-tion. In prior work (Dev et al., 2002), we have meas-

ured the user’s perceptual response to an application

as its performance degrades because of simulated

degradation of the network. For the RSV application,

we were able to show that the most significant net-

work parameter was the available bandwidth. In

actual usage, we expect that an increasing number of

clients will have the effect of reducing the bandwidth

available to any one client. For a satisfactory experi-

ence of collaboration, the most significant factor was

the time necessary to set up the direction of informa-

tion flow in multicast.

We attempted to determine how many client com-

puters could access the server simultaneously, when

both clients and server were in the same laboratory

(that is, we provided optimal network conditions).

Each client was programmed to request images as fast

as possible. We were able to test up to 32 simultane-

ous clients before the server stopped responding to

requests. For this test, we used a simulated user, that

is, a script that requests images as a user might. It is

possible that there would have been an earlier degra-

dation of perceived response with real users.

DISCUSSION

The potential for application of the RSV ranges

well beyond teaching anatomy to first year medical

students. Future uses could include demonstration

and sharing of clinical procedures, collaborative build-

ing of anatomical databases, or collection of a data-

base of anatomical variations for surgery. While we

have found much enthusiasm for the application, we

have also encountered some issues in its deployment.

The first issue encountered, in many schools where

we have tested the application, is the lack of a fully

featured high bandwidth Internet infrastructure. While

the campus backbone is often of adequate bandwidth,

many classroom buildings and most hospital areas pro-

vide only 10 Mbps ethernet connectivity. Multicast

transmission, a feature needed for the collaborative

capability of the RSV, is often disabled on many cam-

pus routers.

A second issue is the need for technical support.

Stereoscopic viewing of images from a remote data-

base, collaborative viewing, and dynamic assumption

and relinquishing of control of a viewing session, all

require technical support for configuration of the

learning stations as well as some technical expertise or

TABLE 1. Student Responses to a QuestionnairePresented at the End of the RSV Session

Number ofstudents

% ofstudents

DemographicsNumber of respondents 74 100Number with strong/moderatecomputer skills

69 93

AttitudeLiked the stereo images 66 89Liked the 3-D pointer 37 53

Usefulness in learningRated the stereo session ashelpful/very helpful

64 86

Added to their knowledge 50 68Helped in comprehendingstructure relationships

59 80

Cleared doubts or confusion 21 28Wanted to use it for review 66 89Wanted to use it for self study 56 76

Wanted to use it for self testing 53 72Valued collaborative style of learning 29 39

TABLE 2. Measured Parameters of the NetworkThat Are Required for the User to Rate the PerceptualExperience of Accessing Remote Images as Satisfactory

Bandwidth 40 MbpsPacket loss <0.01%Delay (one way) <100 msecMulticast setup time <1 sec

281Collaborative Learning Using Internet2

training of the users. Simplifying the configuration also

simplifies the technical expertise required, but with

corresponding loss of pedagogic power. For example,

it is possible to use the application without the stereo

viewing equipment and without any collaboration

requirement. It should be noted that we are in the

process of adding other features of pedagogic utility,

such as recording and play back of an interactive ses-

sion, and interactive labeling and sharing of labels

(Fig. 6). Effective use of these features will require

appropriate training of the faculty and student users.

A third issue is the reluctance of faculty to tamper

with the overloaded curriculum of the first year medi-

cal student. While we have used RSV successfully to

teach our medical students, it has been received

enthusiastically, and the sheer volume of material to

be taught and the need for many media types, includ-

ing the chalkboard, preclude widespread use of RSV

for the Human Gross Anatomy course. We expect to

see more use of the application in undergraduate

anatomy courses and in situations where access to

cadaver dissection is limited. Other possible uses for

an ‘‘interactive online cadaver lab’’ include resident

education, CME courses, simulation facilities, and in

conjunction with live surgery teaching sessions.

Although creating detailed and layered dissec-

tions, and accurately segmented, rotated views of

volume data, is a time-intensive process, we are con-

tinuing with other anatomical parts such that stu-

dents will have the ability to view and interact with

‘‘virtual cadaveric parts.’’ For example, a large data-

base of images (the entire Bassett collection, totaling

more than 1,500 high quality stereo images, from

‘‘head-to-toe’’) has been added, uploaded to our

server, and made available to students and faculty

through a Stanford password-protected web portal.

More recently, we have collaborated with Korean

researchers in creating interactive image data sets of

layered dissections of other body regions (Chung et al.,

unpublished material).

It is cumbersome for physicians to easily revisit

details of their anatomical training as they progress in

their careers. Computer-based approaches, such as

RSV, provide new opportunities for the teaching,

learning, and mastery of gross anatomy. It must be

emphasized that traditional methods (e.g., cadaver-

based) and technologically advanced methods (e.g.,

RSV application) are complementary; the RSV tool is

not intended to replace the ‘‘hands on’’ experience of

cadaver-based anatomy. The RSV technology does

offer students the ability to consolidate, review, and

expand upon what has been learned with cadavers.

In conclusion, the RSV application allows both in-

dependent and collaborative modes of learning

human anatomy over a high-speed, low-latency,

internet-based network. Deployment of the RSV de-

scribed here demonstrates the feasibility for up to 32

individuals on a local network to study dissection of

the same anatomical parts repeatedly and asynchro-

nously. In addition, students and teachers can inter-

act remotely and in real time, creating ‘‘virtual class-

rooms.’’ Thus, the RSV technology appears to be a

Fig. 6. A view of the leg from the Visible Human male. The

image is one of a series of rotated and tipped views, rendered with

muscle and bone opaque. The labeling feature of RSV is displayed.

[Color figure can be viewed in the online issue, which is available

at www.interscience.wiley.com.]

282 Dev et al.

promising addition to the traditional suite of tools

used in teaching gross anatomy.

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