| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Perspectives |
1 From the University of Southern California School of Medicine, KAM 211, 1975 Zonal Ave, Los Angeles, CA 90033. Received December 28, 1998; accepted January 4, 1999. Address reprint requests to the author.
Index terms: Diagnostic radiology, observer performance • Perspectives • Radiology and radiologists
The medical expert is respected for the accurate application of knowledge and experience to medical situations. This constitutes medical expertise, although an understanding of what constitutes expertise and how it is acquired often is elusive. This article is a discussion about visual experts and the characteristics of their activities.
For the purpose of this article, an expert is a person who performs problem solving at a high level by using an organized, complex knowledge base. The expert analyzes the problem at a deeper level and is faster and more accurate at problem solving than the novice. Experts conceive problems in terms of abstract categories. The novice, in contrast, is a learner; the novice practices to develop skills and knowledge within a domain. With progressive guided experience, testing, and feedback, the novice develops an organized knowledge structure. Problems are analyzed superficially, and methods of solution are at a concrete and specific level.
Mastery of the ability to assess scientific fact and observation and to apply results quickly, decisively, and appropriately to a situation is essential in medical action; however, radiology is unusual in the requirement for the mastery of visual factors and the facility to translate accurate observations into knowledge of disease states and their characteristics with the clinical situation. Radiologists believe that the expertise of the interpreter lies in a vast experience of seeing many thousands of radiologic patterns and synthesizing them into a coherent, organized, and searchable mental matrix of diagnostic meaning and pathologic features. Expert radiologists are highly adept at the visual management and synthesis of disease characteristics, which are achieved by translating radiologic and anatomic patterns into diagnostic and management decisions.
Visual stimuli are the strongest of the sensory perceptions of humans: At least 80% of incoming stimuli are visually based. As a consequence, many of our assumptions about the nature of our world, our perceptions of relationships with others, and our interpretations of events and consequences are reliant on observations and our interpretation of those observations. What we see seems more authentic than what we hear. We transfer visual experiences to our memory, where these experiences influence our knowledge and representation of reality.
Because visual representations are incorporated into automatic actions and responses, we may not appreciate how much the complex and demanding task involved in learning a visual pattern and practicing enough to make it automatic has cost us. Reading is an example of complex expertise based on visual cues. To read words, we become expert at the recognition of symbols, we develop a large experience in forming meaningful patterns from the symbols, we locate the symbols in a context of meaning, and we exhaustively practice to automate the entire recognition and application process into progressively more complex representations. Words incorporated into a phrase call up a rich representation (1).
A chess master performs in the same manner as does a radiologist. The chess master has an extensive memory of the configurations of pieces on a chessboard. The expert makes rapid decisions on the basis of a visual pattern of pieces in the context of feasible moves. The expert's chess memory is made up of "chunks" of information that represent units on a chessboard (2). If the pieces are arranged in a meaningless pattern, the performance of the master is greatly reduced.
What visual masters have in common is the motivation to spend long hours of study in one domain, practicing and developing the varied experience to become a master in that domain. One must recognize a huge number of unique configurations and commit them to memory. Relationships between configurations and their variations need to be explored and learned. Long practice leads to commitment to memory and recognition of patterns that are characteristic of the domain (3). This activity is successful if supported by two more elements. To become an expert in the domain, the would-be master must learn, refine, and unify the visual patterns with appropriate and valid information to be retrieved when needed. The ability to develop a memory representation and to retrieve it successfully on the basis of a visual stimulus is crucial to mastery (4).
We establish the building blocks of radiology expertise through long practice and visual registration of many patterns, such that the master-in-training creates a mental library of these images and patterns. At the same time, the meaning of each pattern and its diagnostic implications are established and tested. It is not useful to recognize a pattern without the key to the meaning of the pattern; therefore, the expert radiologist recognizes a pattern and quickly sifts through a network of related information to apply a meaning (the correct meaning, it is hoped) to the pattern. Recognition is only the beginning of problem solving.
The results of studies of eye movement have indicated that radiologists function with visual efficiency, fixating on an important abnormality within 0.5 second of viewing a radiograph (5). After visual fixation on the abnormality, extraction and synthesis of information begin. The experienced radiologist then scans the remainder of the radiograph peripherally but returns quickly to the abnormality. Because information gathering has already begun, the radiologist will then focus on areas that also may show a related abnormality (5,6). Unfortunately, fixation on one abnormality may lead to oversight of another unrelated finding, because we depend heavily on experience in trying to render a complete assessment.
Where and why do radiologists make errors? Despite our speed and accuracy in pattern recognition, if patterns are unfamiliar to us, we perform poorly and fall back on general descriptions without recognizing clues needed for diagnosis. Three sources of radiologic errors have been described: (a) search error, which accounts for 30% of errors; (b) recognition error, which accounts for 25% of errors; and (c) decision-making error, which accounts for 45% of errors (4).
When we examine a radiograph, we recognize normal anatomy, variations in anatomy, and anatomic aberrations. These visual data constitute a stimulus that initiates a recalled generalization of meaning. Linkage of visual patterns to appropriate information is dependent on experience, which has been supported by feedback and validation. The radiologist who has not had an opportunity to develop a rich information network cannot successfully link recognition with clinical problem-solving schemata. Differences between experts and novices in decision-making errors are related to the inability or inaccuracy of the novice in representing a problem in a mental information bank. Sometimes the information simply is not present or is not accurately represented (7–9).
You may wish to reflect on interesting differences between novices and experts that have been examined in other domains: (a) The expert spends proportionately more time establishing a basic representation of the problem before searching for a solution. Although the novice expends more time overall, he or she devotes a smaller proportion of processing time to developing a problem representation (6). (b) The expert rapidly assigns the problem to the appropriate category and proceeds to further processing (7). (c) The expert is able to rapidly align his or her schemata to the specific elements and novel aspects of the case (8).
It is apparent that these differences apply to radiology, as demonstrated by Lesgold and colleagues (8,9). These scientists have determined the pattern of the expert approach to problem solving during diagnostic radiology encounters. The expert initially builds a mental representation of diagnostic schemata with a set of tests or prerequisites to be applied while examining an image and during diagnosis selection. A schema is quickly selected and then controls much of the subsequent thinking about the case. The expert radiologist will continue to test the chosen schema as he or she reaches a diagnosis and seeks to confirm it. The novice radiologist often encounters problems in schema building and application, because testing of the diagnostic schema and/or information is incomplete. Some reasons for this problem are inadequate information, inability to link information to observations, and misinterpretation of observations (or overlooked observations). Novices seem to be less able to modify a schema in response to added or conflicting data, whereas experts remain flexible and innovative and modify schemata considerably (10,11).
Recognition of the differences between novices and experts helps in the training of experts in radiology. The three major characteristics of expertise are recognition of patterns of abnormality, selection of an appropriate diagnostic schema to fit the observations, and maintenance of flexibility in rethinking the decision when new data are presented. The most important step for the novice is the recognition of a pattern of abnormality, which can then be translated into a diagnostic schema. Incorrect or inadequate pattern representation will not provide the hoped for diagnostic result. Novices spend a great deal of time examining the peripheral portions of a radiograph and are more likely to describe chest radiographic findings seen outside the lungs, pleura, and mediastinum than are experts. They are more likely to comment on absent signs or negative findings, in contrast to experts who are more likely to describe findings in the lungs, pleura, and mediastinum (1). This fact reflects back to the ability of an expert to fixate on the abnormality and to distinguish relevant and irrelevant observations. The novice deliberately examines each structure represented on a radiograph and may not recognize relevance and irrelevance. This pattern of observations results in the attribution of prominence to items of little import and inappropriate interpretation of major findings. With practice, however, the novice will build a mental library of patterns of normality and abnormality, along with a library of information. Frequent feedback and affirmation will ensure that this experience grows.
A final distinction between expert and novice is the ability of an expert to excel at recall. Cognitive psychologists (12) have believed that experts could maintain more material in working memory than could others with less experience. It now appears that experts have automated most of the basic skills of observation, and they fit observations into diagnostic schemata. This ability frees mental resources for finer discrimination, consideration of novel aspects of a case, and analysis of new data (10,11). Speed and confidence in the early diagnostic steps allow greater time for reflection and innovation in problem solving. Much like a chess master examining clusters of patterns of expected moves, the expert radiologist distinguishes between relevant and irrelevant information and novel factors in the case. The expert will make more inferences from relevant information and may be more reluctant than the novice to reject information that appears not to fit the puzzle.
Experts have been noted to excel in long-term recall, to have more refined schemata of recognition, and to be capable of finer discriminations, with the ability to tune their perceptions of features to a specific case or situation. Novices tend to recall and infer more information of low relevance to a case (13). The results of problem-solving studies (13–15) show experts to be opportunistic: They take into consideration new possibilities whenever introduced and use new data as it is obtained. Perhaps their speed and confidence in the automated, early steps of analysis allow them the luxury of expending more time, innovative thinking, and energy on the solution to the problem.
We anticipate exciting changes in the future development of radiologic experts: There are more ways to perform imaging, there is an exponentially expanding body of information, and the amount of time for training and reflection is shrinking. Despite these problems, the principles of expertise remain unchanged: Examine multitudes of cases, seek information and affirmation of the findings and diagnosis, and continually update knowledge from reliable sources. Most of all, it is essential that novice radiologists receive our full attention and guidance during their development, so that they can establish the patterns of recognition and the search methods of experts.
References
This article has been cited by other articles:
|
|
 |
|
  D S Brettle, E Berry, and M A Smith The effect of experience on detectability in local area anatomical noise Br. J. Radiol., March 1, 2007; 80(951): 186 - 193. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. L. Kundel, C. F. Nodine, E. F. Conant, and S. P. Weinstein Holistic Component of Image Perception in Mammogram Interpretation: Gaze-tracking Study Radiology, February 1, 2007; 242(2): 396 - 402. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Haller and E. W. Radue What Is Different about a Radiologist's Brain? Radiology, September 1, 2005; 236(3): 983 - 989. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Morrow, E. A. Strom, L. W. Bassett, D. D. Dershaw, B. Fowble, J. R. Harris, F. O'Malley, S. J. Schnitt, S. E. Singletary, and D. P. Winchester Standard for the Management of Ductal Carcinoma In Situ of the Breast (DCIS) CA Cancer J Clin, September 1, 2002; 52(5): 256 - 276. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| RADIOLOGY | RADIOGRAPHICS | RSNA JOURNALS ONLINE |
