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Keywords:

  • education;
  • medical education;
  • imaging;
  • variation;
  • preservation

Abstract

  1. Top of page
  2. Abstract
  3. VIRTUAL ANATOMICAL SPECIMENS
  4. A DEVELOPMENTAL DEFECT IN QTVR FORMAT
  5. THE VIRTUAL ANATOMICAL MUSEUM
  6. LITERATURE CITED

Computer graphics technology has made it possible to create photographic-quality virtual specimens from real anatomical material. One technique for doing this, QuickTime™ Virtual Reality (QTVR), results in virtual specimens that are easily shared on the Internet and displayed as standalone entities or incorporated into complex programs or Web sites. A compelling use of this technology is the sharing of rare specimens such as unusual variations, developmental anomalies or gross pathology. These types of specimens have traditionally been confined to anatomical museums, but could serve a much more useful existence as freely shared virtual specimens. An example presented here is a relatively rare developmental defect in the embryonic aortic arches that results in a right-sided aortic arch coursing posterior to the trachea and esophagus. In a time of ever increasing restraints on the practical side of anatomy education, an Internet-based library of human variation and other rare specimens would be a useful supplement to students' limited exposure to the human body. Since the discovery and preparation of specimens would be the rate-limiting step in producing such a collection, we propose the establishment of a center for virtual specimen creation and preservation through a cooperative effort by gross anatomists and pathologists in contributing the source material. This collection, a work in progress, is available at www.anatomy.wright.edu/qtvr. Anat Rec (Part B: New Anat) 276B:15–18, 2004. © 2004 Wiley-Liss, Inc.


VIRTUAL ANATOMICAL SPECIMENS

  1. Top of page
  2. Abstract
  3. VIRTUAL ANATOMICAL SPECIMENS
  4. A DEVELOPMENTAL DEFECT IN QTVR FORMAT
  5. THE VIRTUAL ANATOMICAL MUSEUM
  6. LITERATURE CITED

Clinically significant developmental anomalies or unusual anatomical variations are discovered occasionally by students or instructors during routine dissections in medical anatomy course laboratories. These conditions might also be known in patients and specifically collected during dissection or autopsy. Such abnormal specimens often have a high instructional value, bringing the theoretical aspects of embryology into the real world and emphasizing the degree of variability in the “normal” human.

Abnormal specimens often have a high instructional value, bringing the theoretical aspects of embryology into the real world and emphasizing the degree of variability in the “normal” human.

Likewise, examples of gross pathologies and surgical procedures have obvious instructional value for medical professionals at all stages of their training.

Although full dissection labs are still a part of the typical medical school curriculum (Drake et al., 2002), there is a trend towards fewer hours dedicated to dissection and greater reliance on prosections in the laboratory experience. With fewer full body dissections being performed for medical education, the availability to our students of these interesting and enlightening specimens is also decreasing. Long-term preservation and easy access to rare specimens are desirable but not often achieved. In the teaching lab, an abnormality or rare variation may be rescued from the students' dissection and preserved for examination by the whole class. With care, these may be kept for several years, but eventually repeated handling and desiccation will seriously degrade the specimen. In educational settings with more limited access to cadaver material due to financial constraints, geographic isolation or cultural considerations, students may only be exposed to one cadaver (or none) and have no hands-on experience with variation and abnormality.

For hundreds of years, of course, rare specimens have been preserved as museum pieces but, unfortunately, many of these specimens do not come out of storage and are not readily available for students' instruction. Typically, museum pieces are only available for study on-site, so unique specimens may only be used by a relatively small number of people. Even when preserved specimens are present in a local anatomical collection, student's access is limited by the desire to preserve the integrity of the specimens. Recently perfected plastination techniques better preserve gross specimens and allow repeated handling and unlimited exposure to the air (von Hagens et al., 1987; Groscurth, 2001). Still, plastinated specimens are confined to a single locale, so their utilization is still not what it could be.

The mass distribution of rare gross specimens has been accomplished, in a way, via drawings or photography in journal articles, atlases, etc. With the advancement of computer graphics in the past decade, ‘virtual anatomy’ has emerged as a valuable substitute for physical access to anatomical specimens (reviewed by Trelease, 2002). Technologies used to create virtual anatomy include artists' renditions of structures created as three-dimensional vector graphics, three-dimensional reconstruction of organs or regional dissections from cross-sectional or CT voxel data (e.g., Visible Human Project and its derivatives (Spitzer and Whitlock, 1998)), and photo-based virtual reality (e.g., QuickTime™ Virtual Reality (QTVR) objects). These technologies each have their strengths and limitations, but have in common the user's ability to rotate specimens horizontally, vertically or spherically, creating the perception of a hands-on three-dimensional experience.

A very simple practical use for virtual specimens is in the lecture hall where the instructor can manipulate the specimen to show features, much as one would with a more intimate group of students in the lab. The same specimens can then be made available to students on demand for their individual study. The various virtual anatomy formats can also include annotations and they can be the core media of complex instructional Web sites and standalone programs.

Photo-realistic QTVR has proven to be an excellent medium for presenting three-dimensional anatomy (Trelease et al., 2000; Nieder et al., 2000). The strength of photo-based VR is its ability to capture fine surface features and textures, creating the impression of the presence of real specimens that continues to be unattainable with rendered model virtual specimens. We have used QTVR to create an online library of anatomical objects, the QuickTime™ VR Anatomical Resource (www.anatomy.wright.edu/qtvr). This collection, a work in progress, currently includes bones as well as various organs, regional dissections and embryological specimens. Each specimen is freely downloadable and available to users in several screen sizes to fit varied needs.

Two examples of QTVR-based tutorial programs, Yorick-the VR Skull (Nieder et al., 2000) and Bones of the Skull (Dispensa et al., 2000), both address skull anatomy, arguably the most difficult three-dimensional puzzle medical students face in their basic anatomy course. These programs have been used successfully to teach anatomical concepts of the skull to students of medicine, dentistry, forensic anthropology and in various allied health and undergraduate programs. The ability to send these virtual anatomy objects and programs to any location having Internet access “opens the doors” of the anatomical museum to the world.

The ability to send these virtual anatomy objects and programs to any location having Internet access “opens the doors” of the anatomical museum to the world.

A DEVELOPMENTAL DEFECT IN QTVR FORMAT

  1. Top of page
  2. Abstract
  3. VIRTUAL ANATOMICAL SPECIMENS
  4. A DEVELOPMENTAL DEFECT IN QTVR FORMAT
  5. THE VIRTUAL ANATOMICAL MUSEUM
  6. LITERATURE CITED

In the course of a recent student dissection, an interesting developmental anomaly of aortic arch development was identified (Fig. 1) and “preserved” in QTVR format. This variant (right aortic arch with left descending aorta, left sided ductus arteriosus and left subclavian originating from an aortic diverticulum), is one of a group of anomalies that occur with a total frequency of approximately 1/1000 (Edwards, 1948; Lippert and Pabst, 1985). This type of anomaly results from an abnormal regression pattern in the developing fourth aortic arches and can result in compression of the esophagus and/or trachea due to the presence of a vascular ring. This specimen is an excellent example of the clinically significant variations that can occur in the great vessels and is useful for teaching aortic arch development.

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Figure 1. Anomalous right aortic arch variation in situ. This rare developmental defect in aortic arch development was discovered by our students during a routine dissection. The figure shows the arrangement of the great vessels, trachea and esophagus before removal from the thoracic cavity with the heart in place (left) and removed (right). The ductus arteriosus was unfortunately torn early in dissection. The right and left subclavian arteries (not visible) originate from the aortic arch and aortic diverticulum, respectively. AsA = ascending aorta; DeA = descending aorta; P = pulmonary trunk; RCC = right common carotid artery; LCC = left common carotid artery; DA = ductus arteriosus; AD = aortic diverticulum; T = trachea; E= esophagus; LV = left vagus nerve.

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The specimen was discovered by students in one of our dissection labs and carefully removed en-block from the body under the direction of the lab instructor. The prepared specimen was mounted for QTVR photography and shot at 10° intervals of horizontal and vertical rotation (36 photos per horizontal row x 6 rows = 216 total photos). Individual photos were corrected for color balance, brightness and contrast and the object was matted on a solid black background using Adobe Photoshop. The corrected set of photos was assembled into a QTVR object movie using QuickTime™ VR Authoring Studio (Apple Computer, Cupertino, CA). The techniques used in QTVR object production have been fully described (Trelease et al., 2000). The multi-row object movie format allows the viewer to use the computer's mouse to rotate the specimen around two axes for viewing from multiple perspectives. This interactivity supports a direct perception of three-dimensional relationships and creates a degree of ‘object presence’ crucial to working virtual reality applications. Representative screen shots of the object movie are shown in Figure 2. The movie can be viewed and downloaded from the QTVR Anatomical Resource Web site. This collection contains approximately 150 specimens and is growing thanks to funding through the National Library of Medicine. These are mostly normal specimens, but examples of coronary bypass, congestive heart failure, cystic kidney disease and other pathologies and variations are being preserved and processed as they become available.

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Figure 2. Representative views of QTVR object. The specimen was photographed from 216 different angles and the images assembled into a QTVR object movie. The object is manipulated through all of the possible perspectives by clicking and dragging the mouse. The full virtual specimen can be viewed at the QTVR Anatomical Resource Web site (www.anatomy.wright.edu/qtvr).

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THE VIRTUAL ANATOMICAL MUSEUM

  1. Top of page
  2. Abstract
  3. VIRTUAL ANATOMICAL SPECIMENS
  4. A DEVELOPMENTAL DEFECT IN QTVR FORMAT
  5. THE VIRTUAL ANATOMICAL MUSEUM
  6. LITERATURE CITED

Virtual specimens like the aortic arch anomaly described here provide a means for students to view three-dimensional specimens they would not otherwise be exposed to. Since QTVR objects can be integrated into lectures, case studies or other web-based course materials, they are in many ways more versatile than traditional museum specimens, and are of course available on demand. The quality of the virtual anatomy experience compared to hands-on dissection and examination is the subject of considerable debate and there are justifiable concerns about computer-based anatomy replacing the hands-on lab experience (Marks, 2000; Aziz et al., 2002). There are certainly many reasons to continue dissection for both the technical and humanistic education of medical students, but virtual anatomy can still fill particular roles in the learning scheme.

Considering the ability of the ubiquitous QuickTime™ (.mov) format to serve as a core media in essentially all multimedia development systems, QTVR specimens could easily be melded into existing or future computer-aided anatomy instruction at all academic levels. With limitations being forced on the anatomical sciences by various curricular factors, students as a whole are being exposed to fewer examples of human variation and have fewer opportunities to see anomalies and pathologies in the gross anatomy laboratory. At the same time, museum collections are being abandoned or are rarely used due to time constraints in the curriculum. A collection of photo-realistic virtual specimens including anatomical variations, developmental defects and gross pathologies, accessible worldwide, would be a valuable resource for the medical and allied health education community.

The number of gross anatomical specimens needed to document the major development abnormalities and interesting variations in human anatomy could easily number in the hundreds. A collection of gross pathology examples would also involve a similarly large number of specimens. Although some of these unusual specimens do surface every year in dissection labs or at autopsy, no single institution can amass a significant proportion of them in a reasonable period of time. Also, very few institutions have the facilities and technical expertise to create high quality virtual specimens. With cooperation of fellow anatomists and pathologists, however, a collection of virtual human anatomical variations, rare human developmental anomalies and gross pathological specimens could be assembled (Fig. 3). Specimens currently in museum collections seem an obvious source. Since they could be photographed using non—or very minimally—invasive techniques, these specimens could be shared without sacrificing their role as archival specimens. Other specimens of interest, perhaps from a “wish list” created by fellow anatomists could be collected from dissections at various institutions as they arise. With a cooperative effort by anatomy educators and adequate funding, a substantial virtual anatomical museum, accessible worldwide, could be developed within a few years.

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Figure 3. Flowchart for creating a virtual museum of rare anatomical specimens.

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LITERATURE CITED

  1. Top of page
  2. Abstract
  3. VIRTUAL ANATOMICAL SPECIMENS
  4. A DEVELOPMENTAL DEFECT IN QTVR FORMAT
  5. THE VIRTUAL ANATOMICAL MUSEUM
  6. LITERATURE CITED