232 IRE TRANSACTIONS ON MEDICAL ELECTRONICS October

Recapitulation of ConferenceMURRAY EDENt, GUEST EDITOR

INTRODUCTION inductive discipline has in its language a set of words

,fN NE concomitant of the proliferation of science in standing for certain more or less vaguely defined notionsthe last twenty years has been a growth of aware- that we may consider to be part of the ideology of theness that each particular human occupation is occupation. Vague though these notions may be-when

permeated with ideas, analogies, and procedures which orig- considered in their fullest generality-the practitionerinated in quite different fields. That the sponsors of the in his special discipline will use these words quite unam-symposium published in this issue have made an implicit biguously when he is talking to colleagues about a concrete

appeal to this principle of interdisciplinary exchange can problem. Physicians discussing a particular case will agreebe seen from the occupational character of the participants. implicitly on the meaning of "symptom" or "diagnosis"The number of different shadings of occupation is but a for this case. Engineers designing a communications linklittle smaller than the number of participants. However we will agree on the meaning of "noise," "attenuation" andcan try a Procrustean solution and divide the participants the like. Unfortunately, many of these words have generalinto two camps: the physicians and the engineers. currency. As a consequence, the person outside a specific

In his welcome to the participants, Dr. Zworykin re- field will believe that he understands the meaning of theseferred to the hostility with which many physicians first words even within the context of the specialty in whichgreeted his proposal to apply engineering techniques to he is a layman.the problems of diagnosis. It is not at all surprising that A recent example of this misconception is well knownphysicians reacted as they did. From the point of view of to communications engineers. The word "information" wasthe practicing physician, this proposal seemed to indicate given a new meaning about ten years ago when it was usedan invasion into the domain of his occupational compe- as the name for a certain highly special mathematical func-tence. Indeed there seem to be some engineers, emboldened tion arising out of probability theory. It is true that thereperhaps by the successes of machine computation in a few is a connection between the interpretation of this functionareas of human activity, who feel that the practice of medi- and the common usages of the word, but this connection iscine can be "rationalized" in the same way that record- a vague one, if only because "information" is a vague wordkeeping, inventory maintenance, and other business proc- in ordinary speech. However, the misconception that theesses and decisions have been. It remains to be seen ordinary meaning of "information" had been mathemati-whether this group has anything substantive to contribute cally defined was very attractive. A number of the biolo-to medical diagnosis. gists and psychologists who saw this part of communica-However, for the most part, engineers have not claimed tion theory as a tool that might be useful to them in their

that they can teach the doctor how to run his business. descriptions of human behavior proceeded to apply theTheir proposals are by and large a good deal more modest machinery of the mathematics in an entirely indefensibleand the goals more limited. In essence, the engineer is sug- way. It is not surprising that so many "applications" ofgesting that some of the tools which have been developed information theory to biology-have ended in blind alleys.in recent years for the physical sciences may also be help- In the interaction of two disciplines, certain individualsful to medicine. from each side are forced into the meeting ground. EachOf course, the application of physical devices to medical side has no choice but to learn at least a little of the flavor

purposes is nothing new; witness the development of X-ray of the other's occupation. Each may find something in thistechniques, of electrocardiography, electroencephalography interchange that will alter his own conceptions and willand the like. At the present time, it has required the co- suggest new grounds for exploration with his own tools.operation of a number of people with diverse skills. Mod- In some measure, even the nature of each occupation isern medicine may well follow a similar pattern. Right now changed by this contact, not only in terms of the techniquesthis suggestion is not much more than an emotional com- and concepts subsumed but also in its motivations.mitment on the part of the engineer. He is usually willing This role of clarification is perhaps the most importantto admit that he is incompetent to attempt any such medi- aspect of interdisciplinary symposia. It is the belief of thecal application on his own. The cooperation of sympathetic organizers of the conference reported here that a certainphysicians is an obvious requirement. Even so, many obsta- degree of clarification was achieved in this meeting. Thecles remain. proceedings, as they appear in the following pages, haveOne of the largest obstacles is that of language. Every been kept in the order of their delivery. However, it

seemed worthwhile to summarize the results of the sym-posium in a way that would bring out some of the ideas

t Dept. of Elec. Engrg., Mass. Inst. Tech., Cambridge, Mass., and upnwihtearcpnsapaedoageadweeNati. Heart Inst., Nati. Institutes of Health, Bethesda, Md. they agreed to disagree.

1960 Eden: Recapitu!ation of Conference 233

MIECHANICAL DEVICES FOR DIFFERENTIAL DIAGNOSIS might be realized in a digital computer. However, theAs evidence that professional interest in mechanical manifest impossibility of achieving a general solution in

aids to diagnosis has progressed beyond the purely verbal every case (even when all the symptoms and diseases arestage, several of the participants in this symposium re- well defined) can be seen if we consider some of the nu-ported on devices which were designed and constructed to merical consequences.perform a particular task similar in certain of its aspects Suppose there were only ten diseases under considera-to the procedures of a medical differential diagnosis. The tion. There would be 210 possible combinations of diseases,slide rule developed by Nash (page 240), the "analog" com- even assuming that the diseases were not rated as toputer described by Brannick (page 247), and the digital severity. In principle we might need a like number of dif-computer program prepared by Lipkin, Davis, Engle, ferent properties and finally 2210 or approximately 10308Ebald, Lane, Sendrow and Berkley are all governed by the combinations of properties which would serve to distin-same principles. In essence they performn a logical task guish a like number of logical possibilities. It is clear thatwhose ground rules are established by what the mathema- while we may say that this unambiguous aspect of diag-tical logician would call "a calculus of propositions." nosis can be formulated as a mathematical problem with

If we are presented with a standard set of properties1 a definite solution, no diagnosis would ever be made if thisthat are identifiable in a particular individual, a standard were the way to make it. The general problem is too big-set of disease classifications, and a mapping2 of all possible much too big for any conceivable computer. It is equallycombinations of properties onto the set of all possible clear that no such solution is required. The diagnosticiancombinations of diseases, then the problem is to find the usually considers his task to identify the most probableappropriate disease or combination of diseases or alterna- and the severest diseases a patient may have. Such a par-tive possibilities of combinations of diseases for the proper- tial solution ("partial" from the point of view of the logi-ties exhibited by the particular individual. cal problem) is very much easier to achieve.One restriction must be noted in the definition before The devices described in the symposium attempt this

we can begin to consider the additional restrictions intro- type of solution. Nash's (page 240) slide rule is the simplestduced in the design of actual devices. The sets of proper- of these devices. Unlike the slide rule of engineering, thisties and diseases are "standard" in the sense that no new one is actually a digital device. There are no gradations inproperties or diseases can be admitted for consideration. judgment introduced either with regard to properties orThat is, if some new property or disease is deemed to be with regard to diseases. We can visualize this slide rule asa useful concept, then a greater or lesser modification of a matrix in which the column headings stand for diseasesthe analytical procedure will be required in order to ac- and the row headings for properties. A "1" is entered incommodate it. If the novel property is added we would the matrix wherever a given property is to be expected inhave a new standard set. The important point here is that a given disease. When the patient's properties are availa-every introduction of a novel concept requires a re-evalua- ble, all the rows corresponding to properties that the pa-tion of the logical organization of the device. Of course tient does not exhibit are removed from the matrix. Nowthis is saying no more than that a new understanding of the columns are examined and the column or columns ex-the disease process may have far-reaching consequences, hibiting a 1 in every place is considered to be the diagnosis.but it is not at all clear that the computer will be able to Due to problems of design, only five of the properties thatdiscover the consequences of this new knowledge by itself. a patient does have can be kept in the matrix and all the

others rmvd;ie,olfiepoetecabeondrdIf all the prerequisite conditions are fulfilled, the prob- o removed; i.e, only five properties can be consideredlem has, in principle, a straightforward solution. Ledley at one time The validity of a diagnosis by this methodand Lusted (page 255) have described the logic of this pro- will depend heavily on the choice of properties that thecedure in some detail as well as one way in which the logic diagnostician chooses to retain. However, before consign-

ing such a slide rule to technological oblivion, it shouldbe pointed out that it is many orders of magnitude cheaper

'"Property" as used here is taken to mean some datum such as than any other device and that, except for unwieldiness,age, height, sex, previous diseases and other aspects of the medical it can be built to do virtually any part of this logical taskhistory as well as symptoms, physical signs, the results of laboratorytests and any other observations that the diagnostician thinks to be The analog computer of Brannick (page 247), despite thegermane. differences in realization employs essentially the same'The reader unfamiliar with the mathematical usage of "mapping" dmay visualize two rows of symbols, one row standing for all possible matrix although the number of properties considered iscombinations of the properties and the other standing for all possihlecomhinations of diseases. A numher of arrows will connect entries veymclagrThpoetisanbgvndfeigin the first row with entries in the second. If an arrow joins property weights and instead of making a diagnostic decision onsuhset s with disease suhset d, the interpretation would he "If a per- the basis of having a nonzero column entry for everyson has exactly the properties specified hy s then he has the com-hination of diseases d." If, however, there is more than one arrow row, the column entries are summed and the column withemanating from s, then the interpretation would he "Such a patient the largest sum is considered to be the likely diagnosis. Inhas disease suhset ci, or d2 or d.," and so on. Thus there is no rulethat restricts the numher of arrows emerging from any symptom set this case, although the electronic gear operates as an analogand similarly no rule that restricts the arrows converging on any dis- computer, both the output and the input are discrete, i. e.,ease set. The only requirement is that at least one arrow must ..''emerge from each property set and one point to each disease set. digital in character.

234 IRE TRANSACTIONS ON MEDICAL ELECTRONICS October

One of the features that Lipkin, et al., have built into considered by Fry are related to the hydrodynamic andthe digital computer program closely parallels the procedure kinematic properties of the respiratory and cardiovascu-employed by the two simpler devices mentioned above. A lar systems. In one sense, this is a "typical" physiologicalsimilar kind of disease-symptom matrix is used and, problem. Its particular relation to this conference lies inas in the case of B3rannick's device, the symptom's sig- the fact that an adequate quantitative description of thenificance is weighted. However, in most instances of its problem is exceedingly complicated. Attempts to describeuse, this program's diagnostic solution is not immedi- adequately a physical system as nonlinear in its behaviorately given. Certain critical properties have been associated as either of these two organ systems can only be madewitlh each disease considered. If there is sufficient cor- with the use of either analog or digital computers. As arespondence between the patient's properties that were matter of fact, Fry has employed both types of computersinitially inserted into the computer and one or more par- in his work.ticular diseases, then the computer will indicate to the Stacy has described some of his work on a closely relatedoperator which additional properties are both critical to phenomenon, although his approach was somewhat dif-that disease and have not as yet been determined on the ferent. Here, the diagnostic problem was to assess thepatient. Indeed, another criterion provides that if the cor- physiological condition of a patient's arterial system in anrespondence is particularly good but that a diagnostic objective manner. In these experiments the analog com-inconsistency exists, the computer will specify which puter was used as a simulator. It was assumed that the"negative" result should be retested. Thus, the computer equations relating peripheral pulse patterns to the centralcan do, in part, what the diagnostician must do even if pulse pattern were known. The computer was wired tohe has recourse to one of the simpler devices. The com- compute peripheral pulse waves, given the central pulseputer is now capable of choosing the critical properties pattern exhibited by the patient, and the equation param-germane to a case once some reasonable correspondence eters were adjusted until the computer output (a simula-is found between the patient's record and a given disease tion of the peripheral pulse pattern) matched that of theor class of diseases. patient.

It is abundantly clear that the ability of the diagnostician Still another problem in this category was presentedto sift the immediate given data and to decide what is by Farrar (page 259). In this instance the "raw" data werepertinent to a particular case is crucial to the diagnostic records of intraluminal pressure in the large and smallprocess. We shall return to a more detailed consideration intestine as a function of time. The goal of the researchof this question later. It is also clear that at many places was to determine, if possible, what regularities there mightthe diagnostic criteria need to be sharpened. be in the waveforms associated with the motor activity of

these organs. There is a large mathematical literatureDEVICES FOR SHARPENING DIAGNOSIS relating to the analysis of waveforms and several of theBY OBJECTIVE TESTS methods, e.g., Fourier analysis and correlation techniques,

Several of the participants discussed the use of devices suggest themselves for application to this problem. Again,that in one sense or another perform a mathematical opera- these techniques are virtually impossible to employ iftion on the "raw" data of some clinical observation in paper and pencil computation is the only available means.order to achieve a more parsimonious or more meaning- Farrar has described the use of a digital computer forful representation of these data. To the practicing physi- this purpose. However, another consequence arising fromcian a particular diagnostic property is useful if it is highly the use of digital computers, and one that may not becorrelated with a specific disease or if it can point to a anticipated by the newcomer to this computing tool, isparticular set of related diseases. The compatibility of pointed out very sharply: The digital computer is such athis property with the body of physiological theory is voracious devourer of data that the problem of preparingsecondary. The difference in the appearance of the erup- the data for presentation to the computer becomes an in-tions of chicken pox and smallpox may have some diag- terminable task. Farrar has mentioned an experiment innostic value. The mechanism whereby one infective agent which 190,000 points on an experimental record were meas-forms one kind of eruption and a second forms a different ured by hand. He also comments that this tremendouskind is literally "of academic interest." From the practical effort covered only a fraction of the data collected. It fol-point of view it does not make any difference if we do not lows that as methods of processing the data become more"understand" the symptom, as long as it serves to clarify rapid, methods of preparing data for the computer mustidentification. However, it is well known that an under- also become more efficient. It should be pointed out thatstanding of the biology will suggest new diagnostic differ- there are available today reliable techniques for preparingentia; witness the large increase in the number of bio- data of this kind for machine computation with little orchemical and metabolic tests in the last few years. no intervention by the experimenter.

So, the interesting aspect of diagnosis for Fry (page A comlplete systemn for quantitatively analyzing mixtures269) and Stacy (page 269) is the description of the symp- of organic compounds has been developed by IT&T Cor-toms of dlysfunction in terms of the physical properties and poration and was described by Taplin (page 273). Once thethe physical behavior of the system. The specific problems experimenter places the sample to be analyzed into thle

1960 Edez: Recap*tu1at)onz of Confe;,ene 23c5

cuvette of the spectrophotometer, the work of measuring The applications described above are each directed tothe amplitudes of the spectrum and the computational de- a specific set of problems. Mrs. Rockoff (page 250') con-tail are taken over by a special-purpose digital computer sidered the problem from the other side of the fence, that isand the data are returned to the experimenter as a set of to say, as a person whose background is in the computa-numbers representing the relative fractions of the several tional art. She described a number of applications of digitalcompounds in the mixture. The incorporation of the data computer techniques to problems of medical and biologicalreading and data computing functions into an integrated interest. It is of interest to note her statement that program-piece of equipment provides a vast increase in the produc- ming for these biological problems is frequently done bytivity of the laboratory worker. medical students concerned with the problem.

Another complete system, this time designed to look It is also of interest to consider here some of the com-for correlations and regularities in the recordings of a ments of Taylor (page 253), since he has presented the ex-large number of psychophysiological variables, was pre- perience of IBM in handling problems germane to the med-sented by Ax (page 263). With the use of the equipment ical field. He stressed in particular the need to prepare thebeing constructed in his laboratory, he anticipates an in- data in a form that would be compatible with machine han-crease of speed of data processing by a factor of 100. dling. A solution of this problem as it relates to experimen-

Since there is a considerable family resemblance between tal data has already been touched upon above. However, thethe various special-purpose "complete" systems, it would same need exists in the reduction of clinical observations toseem instructive to describe the general features of such the appropriate form and in this case there does not exist asystems. "natural" way of reducing medical histories or verbal de-

1) The physical parameters which are to be observed scriptions into a series of digital electric pulses. Taylorare first converted into electrical signals of suitable am- pointed out that great savings in time and energy could beplitude. For example, transducers are available for con- achieved by recording the original observations on punch-verting pressure, velocity, acceleration, or displacement cards or tape (there are typewriters readily available forinto a proportional voltage. In some cases, as in electro- this purpose).encephalography, the signals are already electrical and He also pointed out that while it is feasible for a largeneed only be amplified. institution to prepare its records in a code peculiar to its

2) The electrical signals are displayed, almost invari- needs, such a procedure is completely unfeasible for aably, on a cathode-ray oscilloscope. Visual inspection per- small hospital and a fortiori for the private practitioner.mits some editing, and is particularly useful if some com- Before a diagnostic system can be of appreciable use toponent of the experiment is misbehaving. In many systems him, some standard coding procedure would be required.the electrical signals are also recorded on multichannel FM Several participants commented on the difficulties raised bymagnetic tape so that it can be re-examined and reprocessed this last suggestion. Indeed, the time required to transcribeas often as is needful. a handwritten account of a history and physical examina-

3) The electrical signals are sampled by an electronic tion, for example, is rather small when compared with theswitch, the appropriate channels being sampled at what- time the physician must take in making the examination.ever time intervals the investigator considers to be im- Taylor also remarked that, in his experience, there wereportant. no proposed medical applications which could not be han-

4) The sampled voltages are then converted to digital dled by existing equipment, although some proposals in-pulses by a device called, appropriately enough, an "analog volve the use of enormous programs. This may not alwaysto digital converter" because the input to the digital com- be so in the future, but it does suggest that there are manyputer must be in this form. problems which are not being treated by these machine tech-

5) If, as is usually the case, the digital computer is at niques because the medical scientists are not aware of theirsome distance from the experimental laboratory, then the capabilities.digital pulses are recorded, usually on magnetic tape, in a The issue of relative value of analog vs digital, of special-format that is compatible with the digital computer to be purpose vs general-purpose computers was raised fromused. time to time during the conference. It is obvious that each

6) The complete system of this type requires a digital side had its protagonists, although it is apparent that thecomputer. It also requires a set of programs appropriate to force with which each side defended its point of view wasthe problem. This represents something of a bottleneck at not nearly so great as was the case earlier in the historythis time since programriers are in short supply and most of machine computation. By this time it is clear that nomedically oriented scientists are loath to learn the technical one computational procedure is ideal for all possible uses.details of programming. One should point out to those In fact, for many problems the choice of the particularclinicians who are reluctant to devote much time to study- computational mode is not nearly so important as the skilling mathematics that computer programming requires vir- with which the problem is introduced into the particulartually no mathematical background, although a good pro- machine available. Of course, the choice of an appropriategrammer should be able to reason logically. One must pre- device for the computation is governed in part by the na-sume that a good diagnostician will also have this ability. ture of the problem, but also by the previous experience

236 IRE TRANSACTIONS ON MIEDICAL ELECTRONICS October

and the proclivities of the person responsible for the prob- case the diagnostician examining the results of Tanimoto'slem. Obviously the decision is also controlled by the equip- procedure might be tempted to see if this dichotomy werenent and facilities at his disposal. The economic facts of meaningful in terms of his understanding of the diseaselife are important here as elsewhere. The fact that we are process. Conversely, if a cluster of cases is found, but thesedealing with problems of medical interest does not change cases have been diagnosed as exhibiting various diseases,the features of this decision. However, one conclusion is it may be worth his while to consider if in fact these dis-possible: No matter what procedure is required in the eases have something in common.analysis of medical data by these means, the initial invest- Obviously, such a procedure must be used with caution.ment in capital equipment and in the skills of people It may very well be that the clustering of a particular sethitherto not involved in medical research is going to be of cases is entirely fortuitous since so much depends onmuch larger than the administrators of such research have the set of symptoms chosen for inclusion. As noted before,been used to in the past. in the first attempts Tanimoto has assigned equal weights

to each symptom. Obviously no human diagnostician wouldBASICALLY NON-NUMERICAL AIDS TO DIAGNOSIS approach the problem of diagnosis so blindly. However,

To this point we have considered a diversity of problems there is no intrinsic reason why future extensions of thisrelating to medical and biological science, but they all have program may not take this into account, weigh symptomstwo features in common: differently, and introduce other more sophisticated meas-

ures of distance than the one suggested.1) The specific computational techniques were devel- In recent years mathematicians and engineers workingoped for nonmedical applications, for physics and with computers have become interested in a set of problemsengineering in the main. that are given the generic name "pattern recognition."

2) The computations are essentially numerical or are There is now no doubt that computers can perform numeri-readily translatable into numerical operations. cal operations very many times faster and better than hu-

These are severe restrictions because, in biology and in the man beings. In fact, that is what the computers do best.behavioral sciences, the fraction of problems of interest that Human beings, on the other hand, recognize patterns withhave numerical solutions is very small. On the other hand, great ease and quite unconsciously, whereas computersmany features of medical diagnosis, for example, involve cannot recognize patterns at all. Only after a considerablepurely descriptive terms and these are not easily translated effort on the part of the programmer (and usually theinto numbers that can be added and subtracted meaning- programs are tremendous in size), can computers be setfully; yet, something of this sort is required if diagnostic up to recognize certain regular patterns. However, one mayproperties are to be objectively evaluated. demonstrate that in almost every successful pattern recog-An approach to one such problem has been described nition program written to date, it is childishly easy for a

by Tanimoto (page 280). His construction may be regarded sceptical human being to "doctor" the pattern the machineas a procedure for discovering additional diagnostic classes is supposed to recognize so that the machine will make aof disease. In the procedure of Tanimoto, as in the diag- mistake. However, any human being shown this same pat-nostic devices discussed earlier, it is presumed that the tern will have no difficulty recognizing it immediately.physician is correct in his observations of the various Pattern recognition problems are multitudinous and aresymptoms and signs associated with a given patient. All being studied intensively by psychologists and neurophysi-the patient's properties are given equal weight so that we ologists as well as by computer scientists. Human beingscan visualize a matrix containing only zeros and "l's." can read print, handwriting, braille, sign language. TheyEach case is compared with every other case and the ratio can understand speech and Morse code. They can recognizeof the number of common symptoms to the number of musical compositions, paintings, other people, magazinesymptoms observed in either case is computed. A new advertisements, and many other categories of objects. Inmatrix is formed by these ratios. A suitable numerical fact, in many instances the ability to recognize an object isoperation on this matrix leads to a number called, appro- fixed by just one exposure to the particular object or topriately enough, the "distance" between two cases. This one similar to it.distance is large if the cases have few symptoms in com- One such problem of pattern recognition of particularmon and small if the symptoms are quite similar. If the interest to medical diagnosticians is the problem of recog-original matrix contains a very large number of cases, it nizing certain disease symptoms from complex pictures.would be expected that the cases would tend to "clump'" Three particular cases in point are electrocardiography,together, for if case A were very close to case B and electroencephalography, and radiology. Lusted (page 293)case B were close to case C, cases A and C would in most has addressed himself to this last problem. He points outcases not be very far apart. (This is not necessarily the that it is entirely possible with existing equipment to scan ancase, as Tanimoto has pointed out.) It can be expected that X-ray plate and to store the pertinent information to bein many instances these clusters would correspond to well- found in that plate in a form that would be compatibleknown dlisease types. Suppose, however, that two clusters with the language of a conventional digital computer. Suchof cases are identifiedl as being the same disease. In such a devices have been developed by communications engineers

1960 Edeni. Recapitulatoion of Confereizce 237

in order to store illustrations and photographs or to send At first sight, one of the least promising fields for thethem as a series of pulses from one place on the earth's application of computer techniques would be psychiatry.surface to another (or even as the Russians have done, So far as diagnosis is concerned (in the sense that "diag-from the far side of the moon to earth). So long as the nosis" has been used by the various workers who reportedonly product of this procedure is to reconstruct the initial on the use of computers to suggest a particular disease),picture at some other time and place, the problem is quite computers can be of little help. Beckett states, ". . we can-straightforward. As Lusted states, the tough problem still not use data processing techniques to compare clinical fea-remains to be solved. We must first know what informa- tures of a given patient with a machine memory of stand-tion the radiologist extracts from the masses of light, dark, ardized definitive diagnostic knowledge. Psychiatry willand shadings in between that he sees before him and by have to cover a lot of ground before it can get to thiswhat process of reasoning (or indeed if it is reasoning at stage" (page 248). However, precisely because these cri-all in the Aristotelean sense) he makes his evaluation. It teria are lacking, Beckett and his co-workers have begun theseems fair to say that so far no convincing scheme has task of preparing the case records and notes of psychiatristsbeen suggested for preparing a computer to do anything into a form that will be compatible with machine handlingbut the most elementary aspects of this kind of pattern and that will permit comparison with biochemical, physio-recognition. Even the problem of machine recognition of logical and other test results obtained on the patient. Thesharp, black-on-white, printed characters has not been enormity of the job is revealed by the fact that each pa-worked out to a commercially feasible solution except in tient is evaluated on a scale of 1 to 9 in each of 395 prop-the case of very special type faces of uniform size, un- erties. At present this investigation has concerned itselfsmudged and unbroken. with the preliminary tasks: first with creating the appro-A problem of pattern recognition somewhat further re- priate scales and then with evaluating their reliability by

moved from the immediate concern of diagnosis was comparing the ratings made by different examiners.briefly discussed by Eden (page 265). One kind of pattern Spencer and Vallbona (page 296) are also concernedis both recognized and generated by very young human with ". . the accumulation and use of diverse kinds of medi-beings. This is, in the first instance, the ability to recognize cal and allied information," the specific object of their studya grammatical and meaningful sentence, and in the second being the time course of patients with quadriplegic polio-instance, to speak in grammatical and meaningful sen- myelitis. Here too, the number of individual items recordedtences. Under the stimulation of interest in machine-trans- for each patient is very large. These workers say that theylation and in machine storage and retrieval of written ma- have at present thirty-one different source documents andterial, it has been possible for workers in structural linguis- forty-one cards designed to serve as regular parts of thetics to obtain sufficient support to attack the problem of the record. Nowadays virtually all these data have to be manu-syntactic analysis of language by machine. Thus far it has ally converted to machine form from the hand-written ob-been possible to prepare programs that will do an im- servations and records. In addition, the pertinent physio-portant part of the syntactic analysis of an English sen- logical parameters are picked off the graphical records bytence. Many of the purely syntactic features still remain hand. These authors intend to turn over as much as pos-to be worked out. With regard to the decision regarding sible of this chore to mechanical means.the meaning of a sentence, virtually nothing has been ac- Although these mountains of data would seem to be highcomplished because the process whereby we judge a sen- enough, both these workers and Beckett have stressed thetence to be meaningful or not is itself very little under- fact that one crucial interest is the dynamic change instood. these properties so that many such records may be requiredHowever, the results that have been obtained so far in- on each patient. Fortunately, once the data have been de-

dicate that it may be feasible to do certain aspects of li- posited in the memory of the computer and its adjunctbrary search by machine. Operations such as indexing, tapes, the processing, compilation, computing and compar-cataloging, literature search, and even abstracting can be ing can all be neatly handled by the available machinepartially mechanized. operations. It only remains to restate the obvious: what

is to be compared or which properties to correlate, whatstatistics to compile, are all questions to be answered by the

One task for which a digital computer is particularly investigator. Only if he asks the pertinent questions willwell suited is that of record-keeping. The decision-makers the computer answers be worth all the time, trouble andof large corporations have been quick to recognize the very considerable expense.many advantages of this capacity. It has been suggested An examnple of large-scale data handling has been pre-that the increase in the productivity of the decision process sented by Dunn (p. 295). The National Office of Vitaloccupations is introducing a revolution as pervasive in its Statistics has for some time been using electronic tech-effect as the industrial revolution itself. We have touched niques for tabulating the data which they are collecting.on the record-keeping aspects of medical practice earlier. This agency is presently studying the feasibility of elec-However, several speakers addressed themselves specifi- tronically processing the data in particular studies relatingcally to this problem. to public health and demography. One technique, employed

238 IRE TRANSACTIONS ON MEDICAL ELECTRONiCS October

initially in a study of lung cancer deaths, was stressed by suggested that the mechanical diagnostic techniques haveDunn. In such a study a great deal of additional informa- a very instructive tangential use because they would stimu-tion was desired by the investigators that could not be ob- late the medical students to achieve a more accurate con-tained from the birth or death certificates. In this case it ception of the process of diagnosis.was possible to call for feedback from the physician or the There are some scholars who have held that programsfamily with regard to the pertinent data and concomitantly to mechanize diagnosis are of dubious practical importanceit was possible to obtain the corresponding population in- and of no intellectual interest. If diagnosis is taken in theformation from the records of the Bureau of the Census. particular narrow sense of finding a name for the con-The place of electronic diagnostic aids in the practice stellation of precisely defined symptoms which some indi-

of medicine was discussed by Meneely (page 309), by Kelly vidual exhibits, then such harsh judgments have surface(page 314), and by Almy (page 315). Meneely addressed plausibility. However, even here, as was pointed out earlier,himself particularly to the relevance of computers in train- the technical problems are of considerable difficulty. Iting new doctors. He drew a strong analogy between the di- seems to the author that the conference has cleared the air aagnostic computer and one aspect of medical training. "The bit. This restricted notion of the scope of the conference istraining of medical students consists largely in storing in- unjustified. When a broader definition is taken, it is clearformation in their memories and programming them to that physical technology can make many serious and sig-make logical decisions compatible with that information." nificant contributions to the practice of medicine and theHowever, in evaluating the desirability of preparing ma- understanding of disease. The presentations and discus-chines to perform this task, he added, "If all that came sion at this conference provide a fair sample of what isout of a monumental paper shuffling and magnetic tape being done at present. A beginning has been made andtwirling were a printed list of diagnostic possibilities in the several suggestive directions are being explored.not especially puzzling case of the not especially ill John One final conclusion seems justified. Studies of the feas-Doe, this would be a poor enough product for a massive ibility of diagnostic data processing will have an impactscientific effort. Meneely suggests that the intrinsic justi- on the usage of various medical concepts including "diag-fication of machine use, is in the study of areas such as nosis" and "disease process." For a computer engineer, thedegenerative diseases and the aging process, areas in which question of the precise definition of his terms is a peren-our present knowledge is entirely inadequate. nial one. A computer does not take kindly to ambiguities.Almy also considered the confirmation of diagnosis to On the other hand, the medical diagnostician leans heavily

be one of the simpler aspects of medicine. He too stressed on undefined but, to him, perfectly obvious and unequivocalthe desirability for somie standardization in record-keeping judgments. It may well be that the present attempts to de-and for removing some of the drudgery associated with scribe the diagnostician's task in machine language will leadtaking and handling such data. Almy suggested that elec- to a better understanding for the diagnostician of howtronic computers might be profitably used in statistical he works and to a generally more precise definition of thestudies dealing with prognosis and operative risk'-. He also tasks of diagnosis.