Medical illustration is a field of visual communication with a long history. Traditional medical illustrations are static, 2-D, printed images; highly realistic depictions of the gross morphology of anatomical structures. Today medicine requires the visualization of structures and processes that have never before been seen. Complex 3-D spatial relationships require interpretation from 2-D diagnostic imagery. Pictures that move in real time have become clinical and research tools for physicians. Medical illustrators are involved with the development of interactive visual displays for three different, but not discrete, functions: as educational materials, as clinical and research tools, and as data bases of standard imagery used to produce visuals. The production of interactive displays in the medical arts is examined

Doyle, Michael

Mcconathy, Deirdre Alla

English

NASA Technical Reports Server

N90-22940
INTERACTIVE DISPLAYS IN MEDICAL ART
Deirdre Alla McConathy and Michael Doyle
University of Illinois, Department of Biomedical Visualization and CoUege of Medicine
Chicago and Urbana, Illinois
Medical illustration is a field of visual communication with a long history. Leonardo
DaVinci, inventor, scientist, and illustrator, is perhaps the best known pioneer of medical art, but
many other individuals, such as the famous anatomist Vesalius, also contributed to the develop-
ment of the profession. Understandably, many factors have impacted the field throughout its
growth, but the primary goal of a medical artist-to visually explain information about the health
sciences-has remained unchanged. Other goals such as marketing and advertising of products are
subsidiary to this central objective of presenting educational imagery to health science professionals
and patients alike.
Traditional medical illustrations such as the one shown in figure 1 are static, two-
dimensional, printed images--highly realistic depictions of the gross morphology of anatomical
structures (Netter, 1948; Pernkopf, 1963; The Urban and Schwarzenberg Collection of Medical
Illustrations Since 1896, 1977). Coincidental with technological advances in both medicine and
image production, however, is the expansion of the role of medical art. Today medicine requires
the visualization of structures and processes that have never before been seen. Complex three-
dimensional spatial relationships require interpretation from two-dimensional diagnostic imagery.
Pictures that move in real time have become clinical and research tools for physicians.
Medical artists are uniquely qualified to plan and produce visual displays for use in health
communication. Basic science courses taken within a medical school curriculum prepare them to
be content experts. Prerequisite life drawing, painting, color theory, graphic design and other fine
art courses, and subsequent graduate coursework including anatomical drawing and surgical illus-
tration imbue artistic skills. Using instructional design theory, artists plan goals and objectives,
perform critical analyses of task and learning performance, and evaluate products and procedures.
Medical artists are media technologists as well. They must choose from a plethora of media the
appropriate mode of presentation for the specific content being represented. The objective in
medical art is to incorporate new technologies as both production tools and modes of final pres-
entation. The artists are therefore knowledgeable of a wide variety of media, including printed
images in line, continuous tone or color; projection media such as slides, video, film, and anima-
tion; computer graphics; and three-dimensional models and simulators.
In addition to formal instruction, medical artists possess those abilities often attributed to the
mystical realm of art. Perhaps because of their comprehensive knowledge base relevant to prob-
lems of visual representation, for artists an iterative problem-solving process often becomes auto-
matic to the point of appearing to be intuitive. Previsualization of visual solutions by the artist
allows exploration to occur in an effective, if not well-understood, manner. For example, Ansel
Adams, renowned for his development of the zone system in black and white photography, was
consciously aware of the limitations of film for representing the range of values we are able to see
with the human eye. He could, however, mentally image how a landscape would be recorded by
film, and thereby "see" a predictable translation to guide him. In a similar manner, medical illus-
trators use a combination of factual, theoretical and artistic knowledge to previsualize.
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Clientsandcontentexpertsneedto beinvolvedin theprocessof preparingvisuals,butmany
importantproductiondecisionspertainingto thefinal appearanceof theimagearesolelythedomain
of theartist. Artistsareableto identifyandmanipulatemanyvariableswithpredictableresultsand
recognizethecontributionsof unpredictable"happyaccidents."
Themostfundamentaldecisionsuponinitiating adrawinginvolvecharacteristicsof the light
sourceportrayed.Theimportanceof directionof a light source is well documented. Perceptual
psychologists have demonstrated that an upper-left light source is generally the default assumption
for a viewer, but direction is only one variable to be considered. Two other important considera-
tions are color temperature and intensity, as each of these convey information about spatial rela-
tionships and can be used to invoke affective reactions. The artist sometimes needs to invent the
light source, creating an unreality that is more effective than reality. For example, operating room
lights provide very diffuse, even lighting of the surgical field to avoid fatigue to the surgeon's
eyes; therefore photographs appear to be flat spatially. Surgical illustrators enhance the impression
of space by creating an imaginary, directional light source, with strong highlights and cast shad-
ows. Many other artistic decisions, such as viewer station point, composition, and color harmony,
all impact the final results, and should be entrusted to professional communicators and qualified
artists.
The medical artist embodies a link between the technical and aesthetic realms of visual com-
munication. The skills exemplified by medical artists for the health sciences community can
demonstrate an appropriate model for other fields that need to make judgments about visuals from a
holistic viewpoint.
The importance of a qualified consultant and producer of visuals cannot be overemphasized.
In their report to the National Science Foundation ("Visualization in Scientific Computing,"
McCormick, DeFanti and Brown (1987)) comment that "Because of inadequate visualization tools,
users from industry, universities, medicine, and government are largely unable to comprehend the
flood of data produced by contemporary sources such as supercomputers, satellites, spacecraft,
and medical scanners. Today's data sources are such fire hoses of information that all we can do is
warehouse the numbers they generate, and there is every indication that the number of sources will
multiply." The authors suggest that interactive graphics are the best available solution to managing
this information deluge. They go on to recommend that interdisciplinary teams of computer scien-
tists, engineers, cognitive scientists, systems support personnel, and artists be enlisted to attack the
visualization challenge.
One inevitable question for all types of pictorial displays is how realistic should the image be?
Much debate exists as to the appropriate amount of realism necessary to include in different types
of visuals. Research of the realism continuum and its effect on learning has not, however, estab-
lished usable guidelines to be implemented. The current trend in educational resources is toward
editing of information within pictures to a more diagrammatic style, whereas efforts to improve
simulators are toward maximizing realism. Interactive displays may prove to be a reasonable solu-
tion to the editing question by providing users the flexibility of controlling the variable of realism
and detail themselves. In reality, however, the issue of optimal levels of detail to include in a par-
ticular illustration is most often settled by budgetary constraints or subjective client preferences.
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Medicalillustratorsareinvolvedwith thedevelopmentof interactivevisualdisplaysfor three
different,but notdiscrete,functions: aseducationalmaterials,asclinical andresearchtools,andas
databasesof standardimageryusedto producevisuals.
Healtheducationvisualsarerequiredfor adiverseaudienceincludingpatients,medicalstu-
dentsin training,andexperiencedsurgeons.Theinformationdepictedmaybefactual,theoretical,
abstract,or motor-skill training. Patientsimulatorsare,for example,importantmethodsfor train-
ing manualskillsbecausetheyofferthegreatestbreadthof learningexperiencewith norisk of
damageordiscomfortto thepatient.A successfulsimulatorshouldprovidea highdegreeof pro-
ceduralrealism. A three-dimensionalmodel(fig. 2) usedto trainpersonnelin theprocedurefor
fetalmonitoringexemplifiesatraditionaltypeof interactiveteachingdisplay.
Monitoringafetalheartrateduringlaborrequirestheinsertionof an intra-uterinepressure
catheterandtheattachmentof a scalp electrode to the baby. Placement of the instruments is critical
since misapplication can result in devastating damage to the newborn. Correct positioning of the
instruments requires the technician to palpate anatomical landmarks and visualize spatial
relationships.
To satisfy these requirements in the simulator, medical sculptor Ray Evenhouse mimics soft
and bony tissues with layers of synthetic materials. The structures are made from casts of bones
and sculptures of soft tissues based on morphometric data. The completed simulator consists of a
fetal head that is positioned within the maternal torso by an instructor in a variety of presentations.
Visual and tactile realism is essential so that underlying structures such as the anterior and posterior
fontanelles and facial features can be palpated to orient the trainee. In addition, the motivational
factor induced by a highly aesthetic simulator contributes to the overall success of the model
(Evenhouse and McConathy, 1989).
A quite different simulation is represented by an electronic textbook recently developed by
Doyle (O'Morchoe and O'Morchoe, 1987) as a tool for teaching histology, the study of cell and
tissue biology, to medical students (fig. 3). This prototype system operates on an IBM PC micro-
computer fitted with both a high-resolution graphics display, capable of 256 on-screen colors, and
a separate monochrome text display. The textbook uses the interactive digital video (IDV)
interface, a device-independent process for user interaction with digital video images.
A student operating the system is presented with a menu from which a particular histological
section is chosen for viewing. A realistic video image of that section is then called up from the
disk and displayed on the color monitor. The student is then able to interact directly with the video
image by pointing to an area of interest with a mouse and pressing a button. The system responds
by displaying descriptive test on the monochrome monitor, which explains the pertinent facts about
that particular image feature. For example, if the student points to a muscle cell within an image of
heart tissue, the text which is displayed on the monochrome monitor explains in detail the salient
morphological characteristics of cardiac muscle, how this type of muscle tissue compares to skele-
tal and smooth muscle, and so on. This atlas is an attempt to create an entirely intuitive user inter-
face for the student. A specific goal was to eliminate the distraction of labeling every important
histological structure on the screen simultaneously while still allowing the user instant access to the
exact conceptual elaboration which he or she desires.
It is possible to reverse the above-mentioned situation so that the student can type in a struc-
ture name on the keyboard and the system then displays an image with the pertinent structure
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highlighted.TheIDV interfacecanalsobeusedto correlateoneimageto anothersothatthe
selectionof ahistologicalstructureresultsin thedisplayof eitherhigheror lowermagnification
viewsof thatparticularimage. Thisallowsthestudento zoomin from anorienting,low-
magnification,light microscopicview, throughconsecutivehigher-magnificationimages,all the
way to theelectronmicroscopiclevelandbackagain.Thepossibilityis alsobeinginvestigatedof
usingaspeechsynthesizerfor textoutputaswell asavoice-recognitionsystemfor usertext
queries.
Theseexampleshighlight therangeof possibilitiesfor teachingwith interactivevisuals.The
opportunitiesfor studentsto learnin realtime,encountervariations,self-editinformation,and
adoptlearningstrategiesbestsuitedto theirownneedsrepresentamajoradvancementin
education.
Anotherburgeoningareaof interactivedisplaysinvolvesvisualsasclinicalandresearch
tools. Theadventof computertechnologyin combinationwith newtechnologiesof diagnostic
imaginghasprovidedphysiciansandresearchersnewmethodsof visualization.
Theimagingmodalitiesof computedtransmissionandemissiontomography,magneticreso-
nanceimagingandultrasoundarerevolutionizingmedicine."Improved3Dvisualizationtech-
niquesareessentialfor thecomprehensionof complexspatialand,in somecases,temporalrela-
tionshipsbetweenanatomicalfeatureswithin andacrosstheseimagingmodalities"(Computer
Graphics,1987).For example,usingthecomputeraplasticsurgeoncanmodifyapatient'sfea-
turesto simulatepostoperativeresults.Suchmanipulation,basedoneachpatient'sdiagnostic
imagery,canbeapowerfultool to helpplana surgeryandalsoallayapatient'sanxietyaboutthe
outcome.Anotheremergingapplicationof computervisualizationis thecustomdesignof
orthopedicreconstructionsuchaskneereplacementsthroughnoninvasive3D imaging.
Suchdevelopmentsin diagnosticimagerydictatearadicaldeparturefrom conventionalmeth-
odsof teachingandcommunicatinganatomicalinformation.Medicinehastraditionallyreliedon
frontal,anterior-posteriorviews,but this flattenedperspectiveis notsufficient. Theexplosionof
diagnosticimageryhasshatteredconventionsof orientationandrequiresvisualizationof oblique,
cross-sectionalandotheruniqueviewpoints.Usingcomputer-aidedesignsoftware,studentscan
rotatestructuresto improvetheirspatialunderstanding.
Thesemajorchangesin spatialrepresentationrequireheightenedattentionto fundamental
aspectsof preparingvisuals,suchasorientingtheviewer. Theimpressionof spacecanbe
enhancedby unusualobliqueviews,but is usefulonly whentheuseris properlyoriented.Failure
to establishtheviewer'sorientationseriouslycompromisesthecommunicationof thevisual,yet
wecontinueto seeslidesflashedwith little ornoorientinglandmarksor graphicelements.This
leavestheviewerwith orientationasafirst cognitivetaskratherthanproceedingto the intended
taskof informationprocessing.
Researchconcerningorientationandmentalrotationof figureshasprovidedabodyof theory
whichcanpotentiallybeusedto solvequestionsof orientation;however,applicationof thesetheo-
riesis still sorelylacking. In surgicalillustrationit is unclearwhetherit isbetterto depictaproce-
durefrom thesurgeon'spoint of view duringthesurgery,or whetheraview of thepatientin
anatomicalposition(upright,anterior-posteriororientation)isbest.
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Anotherproblemthatplaguesvisualcommunicatorsis a lackof standardizationof bothver-
balandvisualsymbols.Specialtyareasoftendeveloprepresentationsthatarelearnedby users
overtime, butcomprehensive"dictionaries"of graphicelementswouldbehelpful to assistthenew
learnerandto assureconsensusof interpretation.
Standardizationof graphic elements would also maximize the amount of information which
could be encoded into graphic symbols. For example, illustrators often employ arrows as devices
for portraying the idea of direction, movement, or force. What do different types of arrows mean?
In medical art there is a tendency to use simple, two-dimensional arrows to imply direction of
movement. A three-dimensional arrow can also encode information about force, and can be made
more or less monumental to correlate to the amount of force produced. Arrows drawn in perspec-
fives that seem to pierce space can give information about complicated movements such as spirals
or rotations. Unfortunately, no standardized vocabulary for graphic elements exists for medical art
or for most specialties.
Standardization of data used to construct images would also be a boon to improving accuracy
and production efficiency. At present, as each artist begins an illustration he or she must subjec-
tively synthesize information from many resources. A database of morphometric information
would assist the artist by providing measurements for an idealized form that can be manipulated,
rotated, and embellished using the computer. Following the approach of human factors specialists
in the design of tools and environments, the artist would have data sets of measurements to
describe the range and standard for forms. Image banks would alleviate the necessity of "rein-
venting the wheel" (or kidney, brain, or heart in the case of medical art!) every time a new illus-
tration is requisitioned. This way of thinking is somewhat antithetical to the traditional illustrator's
mode of thinking, in which the product of artistic labor is considered to be a personal, unique
interpretation of the subject matter--a problem that may impede acceptance of stock supplies of
imagery.
A project that addresses the issues raised thus far is under way at the Department of Bio-
medical Visualization at the University of Illinois at Chicago. Aptly named The DaVinci Project,
the interdisciplinary research group, consisting of experts from engineering, institutional com-
puting, educational development, supercomputing, urban planning, architecture, medical imaging,
and medical illustration, aims to create a RESOURCE CENTER FOR ANATOMICAL IMAGING.
Using methods traditionally employed at a microscopic level, the DaVinci Project will establish a
comprehensive, accurate description of standard human gross anatomy and its development
through time, based on quantitative and qualitative data gathered from diagnostic images and actual
specimens (fig. 4). Morphometric analysis and stereology will be used to develop a computer-
based stereoanthropomorphic database which can be manipulated, analyzed, and enhanced for
various visualization purposes. The database will benefit diverse fields including medical
education, bioengineering, anatomical simulator design, forensic science, biological process
simulation, surgical instrument design, pharmaceutical research and development, military
technology, sports equipment design, and missing persons research.
The DaVinci Project will contribute to teaching efforts, provide a research tool to clinicians
and basic scientists, serve as a production tool for artists, integrate diagnostic imagery, and utilize
computer technology to standardize and visualize information. Such an endeavor summarily
represents the trend toward approaching visual information interdisciplinarily, interactively, and
electronically.
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REFERENCES
Doyle, Michael D.; O'Morchoe, Patricia J.; and O'Morchoe, Charles C. C.: A Microcomputer
Based Histology Atlas. Proc. Amer. Assoc. Anatomists, 1987.
Evenhouse, Raymond; and McConathy, Deirdre A.: Development and Construction of a Fetal
Monitoring Simulator. J. Biocommun., vol. 16, no. 1, Winter, 1989.
Netter, Frank: Ciba Collection of Medical Illustrations. Ciba Pharmaceutical Products, Inc.,
Colorpress, 1948.
Pemkopf, Eduard: Atlas of Topographical and Applied Human Anatomy, Vols. I, II. W.B.
Saunders Co., 1963.
The Urban and Schwarzenberg Collection of Medical Illustrations Since 1896. Urban and
Schwarzenberg, 1977.
Visualization in Scientific Computing, Computer Graphics, vol. 21, no. 6, Nov. 1987.
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Figure 1.- TraditionalmedicalillustrationbyDeirdreMcConathy,depictinggrossmorphologyof a
cadaver heart.
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ORIGINAE PAGE
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Figure 2.- Interactive patient simulator developed by Evenhouse used to teach instrumentation for
fetal monitoring procedure.
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ORIGINA[ PAGE
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Figure 3.- Electronic textbook developed by Doyle (1987) used to teach medical students about
cells and tissues.
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Figure 4.- Representation of the DaVinci Project's aim to use two-dimensional anatomical imaging
data to produce a serially reconstructed three-dimensional computer database of standard
anatomy.
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Interactive displays in medical art

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