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European Journal of Radiology 82 (2013) 1584– 1587

Contents lists available at SciVerse ScienceDirect

European Journal of Radiology

journa l ho me p age: www.elsev ier .com/ locate /e j rad

ditorial Musings

istory of metaphoric signs in radiology

tephen R. Baker ∗, Yasser M. Noorelahi1, Shanchita Ghosh2, Lily C. Yang3,avid J. Kasper4

ew Jersey Medical School, University of Medicine and Dentistry of New Jersey, 185 South Orange Avenue, Newark, NJ 07103, United States

r t i c l e i n f o

rticle history:eceived 4 April 2013ccepted 9 April 2013

eywords:etaphoric signs

adiologyitation trends

a b s t r a c t

Purpose: To survey the nearly 100 year history of metaphoric sign naming in radiology describing thepace of their overall accumulation in the radiology canon, their specific rates of growth by modality andsubspecialty and the characteristics of the referents to which the signs are attached.Materials and methods: A comprehensive list of metaphoric signs was compiled from a search of articles inseveral major English language radiology journals, from a roster compiled in a monograph on the subjectpublished in 1984 and from a search of several databases to find signs published in the first half of the20th century.Results: The growth of radiological metaphorical signs naming was slow for several decades after the first

one was published in 1918. It then increased rapidly until the 1980s encompassing all modalities andsubspecialties. Recently the practice has shown a marked and steady decline.Conclusion: Metaphoric sign naming was a frequently reported contribution to the radiological literaturein the second half of the 20th century corresponding with Radiology’s growth as a descriptive discipline.Its decline since then may be a consequence of Radiology’s evolution into a more analytic, data-drivenfield of inquiry.

. Introduction

The detection of normal anatomy, pathologic derangements andhysiologic processes by the various techniques of radiology is to

great extent the result of the clever and insightful applicationf physics and engineering to uncover abnormalities and renderiagnoses. But the descriptions of the manifestations of the picturesreated by these techniques has been no less a product of ingenuitynd creativity. In large measure we have come to recognize andemember the various patterns of disease and injury revealed on

he images we review by the names we have given to them.

One of the ways in which our perception of both normal andbnormal appearances revealed by imaging is identified is by

∗ Corresponding author at: University Hospital (UH), 150 Bergen Street Newark,J, United States. Tel.: +1 973 972 5188; fax: +1 973 972 7429.

E-mail addresses: bakersr@umdnj.edu (S.R. Baker), dr.ynoorelahi@gmail.comY.M. Noorelahi), Ghoshs1@umdnj.edu (S. Ghosh), yangclily@gmail.com (L.C. Yang),kasp86@gmail.com (D.J. Kasper).1 Address: 201 Railroad Ave, Apt# 317, East Rutherford, NJ 07073, United States.

el.: +1 312 714 5247.2 Address: 90 Bergen St., Newark, NJ 07103, United States.

el.: +1 732 566 9028.3 Address: 25702 Minoa Dr., Mission Viejo, CA 92691, United States.

el.: +1 609 610 0102.4 Address: 1 14th St. Apt 1001, Hoboken, NJ 07030, United States.

el.: +1 201 925 9251.

720-048X/$ – see front matter © 2013 Elsevier Ireland Ltd. All rights reserved.ttp://dx.doi.org/10.1016/j.ejrad.2013.04.005

© 2013 Elsevier Ireland Ltd. All rights reserved.

affixing to each of them a specific sign with metaphoric content.Since the first such sign was reported in a radiology journal in 1918[1], they have proliferated as valuable components of the diagnos-tic process in every subspecialty of radiology, collectively becomingan integral feature of their respective nomenclatures. Some like theapple core sign for colonic cancer have become enduring elementsof radiology education whereas others have been quickly forgottenand are now merely historical curiosities.

A classic compendium on this subject is Eisenberg’s monograph,Atlas of Signs in Radiology, which was published in 1984 [2]. This is acompilation of 455 signs, each accompanied by an illustration and areference. That long list can be further disaggregated into eponymicsigns, honoring the perspicacity and the fame of their discoverers,metonymic signs so named as one part of the anatomy calls to mindan imaging configuration elsewhere in the body and metaphoricsigns for which a visual pattern from another realm of knowledgeprovides a novel resemblance. Only 15 of the signs recorded byEisenberg bear the names of a physician luminary. Anatomic evo-cation was the source of 163 signs. But the overwhelming majoritywere characterized by a metaphoric relationship. The conceptualreferences for them stem from a wide variety of inherently non-medical objects and conformations.

In fact, the heightened emphasis on metaphor as a namingstrategy is a special attribute of radiology. In a recent report,we compared our specialty with six others in which the physi-cal appearance of microscopic or macroscopic configurations were

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discernable on plain radiographs. CT examinations were the sec-ond most commonly cited source of newly reported metaphoricconnections followed closely by ultrasonography and conventionalradiographic studies aided by the intravascular administration of

Table 1The distribution of published metaphorical signs by imaging modality.

Modality Metaphorical signs

Radiography 388Without contrast material (249)With injected contrast material (66)With ingested contrast material (49)With rectal contrast material (24)

CT 112US 75

S.R. Baker et al. / European Journ

ssential features of their distinctive corpus of knowledge [3]. Asecorded in major textbooks and medical dictionaries, we foundhat radiology by far is the most metaphoric specialty among thoseor which visual recognition provides a major focus of informationnd insight.

Since the 1980s discoveries provided by both basic radiographynd especially by advanced imaging modalities have continued torow apace as have additions to the store of applied metaphors.his has prompted us to survey the entire history of radiology fromts beginning to the present day in order to provide an updateegarding the distinguishing features of the roster of metaphoricigns, noting their particularities by decade of origin, modality,ubspecialty and category of reference.

. Materials and methods

The now expanded list encompassing metaphoric signs and theetails of their introduction was derived from information providedy three distinct source modes: (1) direct access to the cited refer-nce in which the sign was announced, (2) database searches and3) signs listed in Dr. Eisenberg’s monograph.

The table of contents of individual issues of several of the mostidely disseminated English language journals of radiology was

urveyed to identify metaphoric signs as revealed by article titles.e referenced each issue including the most current one as well as

ll older ones respectively from 1923 for Radiology [4], from 1965or AJR [5], from 1960 for Clinical Radiology [6], from 1928 for theritish Journal of Radiology [7], from 1990 for the European Journalf Radiology [8], from 1991 for European Radiology [9], from 1999or the Canadian Association of Radiologists Journal [10], and from977 for JCAT [11]. The span of years in which article titles wereirectly inspected was limited by the date of each journal’s earli-st availability in the periodical collection of our medical school’sibrary. From a review of references in each article, we frequentlyound earlier citations for the same sign. By this process, we wereble to identify the titles of all articles in every issue of each journalrom their inception to the present. Thus, we could then establishhe bibliographical site and time of provenance for all metaphor-cal signs, which were identified by their appearance in articlesitles.

At the same time we sought further evidence of the existencend origin of other signs through database searches. Each of theforementioned journals was interrogated by the key words of sign,etaphor and appearance. Searches through Medline extended

rom 2012 retrospectively to 1946. A Google Scholar Search wasmployed to find pertinent information from the present to earlyn the 20th century. The Index Catalog Search engine, which rangesrom 1961 to before 1895 helped us uncover other signs, someeported early in the twentieth century, according to the promptords of radiology, sign, and appearance.

Eisenberg’s monograph was published in 1984. Its extensive bib-iography was consulted as well to determine the initial source ofach metaphoric reference that was displayed in it. Together theseources were complementary for the accumulation of signs and thelacement of each according to their date of publication.

To be included on the list, the sign had to be accompanied by aicture generated by one of the techniques of diagnostic imaging.urthermore that image had to reveal the hallmarks of the assertedetaphoric label as assessed by us.

. Results

The first example of a metaphoric reference applied to a dis-inctive finding on a radiographic image was published in themerican Journal of Roentgenology in an article by A.W Crane

Fig. 1. Metaphorical signs as designated in article titles in English language radiol-ogy journals from 1910 to the present.

entitled “Inverted comma sign in pulmonary roentgenology”. Thecurvilinear configuration evocative of a backward comma denotedthe course of conjoined layers of pleura in the right upper lungfield that are retained through life when the azygos vein is haltedon its embryological journey from the lung apex to its normal posi-tion adjacent to the junction of the trachea and right main stembronchus. Although Crane failed to note the etiologic and spatialrelationship between the thin pleural interface and the ectopic vein,the metaphoric connection between an anomalous radiographicappearance and the curvature of the grammatical mark was estab-lished.

Since then, the propensity to ascribe appearances of visual fea-tures from a non-medical discipline to a finding on a radiographicimage has become commonplace, as revealed in Fig. 1. In the 1920s,1930s, and 1940s, such metaphoric associations were infrequent inthe literature at first with only a few cited per year in English lan-guage radiology journals. By 1950 only 69 metaphoric signs couldbe retrieved through our various searches. However, metaphoricsign naming gained popularity in the early 1950s and soon there-after became a frequent subject of published articles. The practicepeaked in the 1970s and 1980s before declining rapidly in the 1990sand the first ten years after 2000. Moreover, at the time of thiswriting, with one fourth of the second decade of the 21st centurycompleted, if present tends continue, there is likely to be a furtherdecline in this practice over the next few years.

The contribution of each of the major modalities to therepertoire of metaphoric signs is shown in Table 1. Non-contrast-enhanced basic radiography patterns of abnormality or anomalyhave provided the stimulus for the plurality of metaphoric labels.Of the 680 signs we were able to compile, 249 related to a finding

MR 52Angiography 43Nuclear scan 7Mammography 3

1586 S.R. Baker et al. / European Journal of Radiology 82 (2013) 1584– 1587

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ig. 2. The number of cited metaphorical signs by subspecialty from 1918 to theresent.

ontrast material. Next in frequency were images from MR studiesnd GI contrast-enhanced examinations. In comparison mammog-aphy and nuclear medicine images have not been fertile fields forhe establishment of metaphoric linkages.

As seen in Fig. 2 when comparing subspecialty foci, clear differ-nces in the frequency of metaphoric references become evident.nvestigations of the gastrointestinal tract had led the way as

source for these relationships. Next most common was theusculoskeletal system followed by images of the pulmonary,

enitourinary, and neurologic systems, respectively. The vascularract and the breast, both relatively new subspecialty concentra-ions in radiology have engendered a relatively sparse collection of

etaphoric signs.Relating the date of introduction of such signs to both decade

nd subspecialty reveals that the peak of metaphoric naming activ-ty for nearly all imaging disciplines was between 1975 and 1985Fig. 3). This period of maximal activity was preceded by a sharpncrease and succeeded by an equally abrupt drop off. For eachubspecialty area the pattern of rise and fall were similar, althoughusculoskeletal radiology, now heavily dependent on CT and MR,

eached its apex before the introduction of those modalities. Neu-oradiology had two pinnacles, one after the introduction of headT in the 1970s, and a subsequent one in the 1990s, a time whenoth CT and MR had each further expanded their capabilities withhe introduction of later generation scanners.

The influence of modality on the frequency of metaphoric signs related as well to the time of introduction of new imaging tech-iques. Prior to the 1970s of course, radiography was the sole source

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ig. 3. The frequency of citation of new metaphorical signs by decade disaggregatedy subspecialty.

Fig. 4. The proportional distribution of categories of referents contributing tometaphorical signs labeling.

of distinctive imaging appearances susceptible to being labeled byan association with a non-medical moniker. However, by the 1990s,relatively fewer metaphoric signs attached to appearances on plainfilms or conventional radiography contrast studies were published.Now the bulk of metaphoric allusions is stimulated by CT and MRfindings.

The references for these signs encompass a wide range of char-acteristic shapes, most of them emblematic of real objects but witha smattering reminiscent of well-remembered imaginary figures.Any categorization of this diverse assemblage would be arbitrary,but the accompanying chart (Fig. 4) is an attempt to allocatethem into distinct groups. Man made objects other than weapons,apparel, or architectural elements were by far the most commonreferent. Foods, tools servicing foods and animals were next mostfrequent. Natural phenomena and geometric shapes, as well asactual letters and numbers were together evocative of approxi-mately one fourth of all signs. The broad range of conformationsthat have stimulated authors to attach them to specific imagingappearances indicate that the criteria for inclusion as a metaphoricreference is really unlimited in scope.

4. Discussion

The popularity of metaphor as a naming device in radiology asevidenced by the encyclopedic collection of signs accumulated overnearly the last 100 years is a testament to its compelling power toaugment initial interest about distinctive appearances of specificimaging findings and to engender remembrance of them after afirst viewing. A good metaphor is capable of providing fresh insightto link what is familiar from one established discipline to a novelvisual representation in a new medium. The process of metaphoricnaming is ubiquitous in narrative discourse. Its application to imag-ing has expanded radiology’s lexicon and by so doing enriched the

descriptive range of each of its subspecialties.

The inclination to insert metaphoric allusions into the knowl-edge base of imaging was relatively slow at first, limited in partby the relative paucity of published articles in radiology journals

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n the first half of the twentieth century, as compared with thexplosive growth of scientific publishing, including those directedo imaging, in more recent times. The impetus for the expansion ofhe roster of such signs after 1950 was their ready acceptance byournal editors who appreciated the allure of arresting metaphors.

any issues of general radiology periodicals in the period from950 to 1980 included at least one report in which was cited a newign, the form of which was most often metaphoric in nature. Thepecific abnormal patterns and spatial relationships depicted onT and ultrasonography images further expanded the repertoire ofetaphoric linkages. But just as promptly as this naming practice

ecame more common so to has been its decline.Why has the frequency of metaphoric labeling diminished in

ecent years? One might have predicted that MR, unlike CT and US,ould retain a vigorous reliance on metaphoric sign reporting, inas-uch as it has enabled the recognition of new anatomic distinctions

fforded by its ability to provide pictorial definitions of adjacentoft tissues structures, especially in the extremities. MR can reveals discrete entities muscles, tendons, ligaments and nerves, whichre to a great extent undifferentiated by plain radiography andven by CT. Such newly distinguishable anatomical presentationsould have been the stimulus for an additional trove of illustrativeetaphorical signs. Yet for the most part that prospect has not been

ealized.By the 1990s articles offering metaphorical signs in the imaging

iterature, by and large, became less frequent. Part of the changeeflected an apparent deflection in many journals away from purelyescriptive reports to a greater reliance on quantitative distinc-ions and statistical validations as the desired substance of scientificontent. To gain acceptance one had to offer more than a novelesignation connecting an imaging appearance to an analogousonfiguration from another realm of knowledge. Part of such a turnway from metaphoric signs might just have been a change in fash-on about what constitutes a valuable contribution to the medicaliterature.

But more probably the decline of metaphoric naming is in facttself a signal of the transformation, or more precisely, the matu-ation of radiology as a learned subject claiming scientific import.adiology in many ways is akin in its development to both geog-aphy and astronomy. Like diagnostic imaging each is spatiallyentered. Also both are becoming characterized as data-driven,ypotheses generating disciplines even though they were ini-

ially primarily concerned with identifying places and giving themames. Research in both is now directed to measuring phenomena,rocess interaction, and to advanced techniques of mapping. Sooo is radiology evolving in a similar fashion, outgrowing its earlier

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adiology 82 (2013) 1584– 1587 1587

emphasis on picture identification, to become a crucial means ofphysiologic investigation on both the micro and macro levels. Inthis context, the value of metaphoric naming may now be consid-ered somewhat passé, a charming remnant if you well of radiology’sinteresting beginnings but no longer a major element in its currentand future agendas.

5. Conclusion

The practice of metaphoric naming had led to a profusion ofsigns demarcating specific appearances revealed by all imagingtechniques and encompassing all subspecialties in radiology. Thispredilection was used sparingly early in the history of radiologythen had a rapid rise followed by an equally rapid decline. Its loss ofcogency currently coincides with the evolution of radiology towardbecoming a more analytical and less primarily descriptive disci-pline.

Conflict of interest

All authors confirm that there are no conflicts of interest. Thearticle is not under consideration for publication elsewhere. Allauthors approve the publication.

Acknowledgement

The authors would like to thank Naiim Ali, MD, for his contribu-tion toward collection of the data for our paper.

References

[1] Armen RN, Morrow CS. The abnormally situated azygos vein: X-ray demonstra-tion of its distention in congestive failure and in various positions. Circulation1956;14(6):1079–83.

[2] Eisenberg R. Atlas of signs in radiology. Baltimore, MD: Lippincott Williams &Wilkins; 1984.

[3] Baker SR, Partyka L. Relative importance of metaphor in radiology versus othermedical specialties. Radiographics 2012;32(1):235–40.

[4] Radiology 1923–2012. September 1923; 1(1) through June 2012; 263(3).[5] American Journal of Roentgenology 1965–2012. September 1965; 95(1)

through June 2012; 198(6).[6] Radiology 1960–2012. January 1960; 11(1) through June 2012; 67(6).[7] Journal of Radiology 1928–2012. January 1928; 1(1) through June 2012; 85

(1014).[8] Journal of Radiology 1990–2012. January 1990; 10(1) through June 2012; 81(6).

[9] Radiology 1991–2012, 1991; 1(1) through June 2012; 22(6).10] Canadian Association of Radiologists Journal 1999–2012. August 1999; 50(4)

through May 2012; 63(2).11] Journal of Computer Assisted Tomography 1977–2012. January 1977;1(1)

through June 2012;36(3).