This study provides one of the only reports of radiologists’ use of CAD and double reading in clinical practice in the U.S. and their perceptions related to use of either the computer or a second radiologist in their interpretive process. Most radiologists reported using CAD, compared to few radiologists who double read, despite the positive perceptions of double reading. We found that radiologists perceived double reading to improve cancer detection rate compared to CAD, but they perceived recall rates to be increased by CAD compared to double reading. While nearly half of radiologists agreed that CAD improves the profitability of breast imaging, very few agreed that double reading improves profitability. While most radiologists thought double reading takes too much time, they believe it does protect radiologists from malpractice suits.
Radiologists’ perception that CAD increases cancer detection rate and recall is likely to stem from the primary function of current-generation CAD programs, which is to provide output solely to alert radiologists about potential cancers, not reassure them by absence of CAD prompts. If used as designed, CAD is supposed to increase recall rate and biopsy rate in order to achieve increased cancer detection rate (that is, the radiologist is supposed to recall every exam judged appropriate for recall before displaying CAD marks, and then to recall additional exams when the CAD prompts are judged to be appropriate). Double reading, especially if used with consensus reading, may achieve the goal of increasing cancer detection rate without affecting recall rate, or of decreasing recall rate without affecting cancer detection rate.22–24
Most radiologists thought CAD reassured mammographers however, the absence of CAD output could also falsely reassure radiologists. Double reading was perceived even more often than CAD to improve cancer detection rate, but was less often perceived to increase recall rate. These perceptions suggest greater confidence in colleagues’ interpretation (double reading) compared to that of a computer (CAD). The trend for increasing use of CAD rather than double reading will continue to shift clinical interpretation towards computer- rather than colleague-based aids. The view that CAD increases profitability of breast imaging may be related to the additional reimbursement provided when using CAD, and the perception of CAD not taking too much time, unlike double reading.
Radiologists’ perception of CAD and double reading is important for clinical practice at the level of individual radiologists, and also from a larger perspective related to diffusion of technology. As diffusion of CAD increases, it is important to understand radiologists’ perceptions since they are the end users of the technology, yet may not be the primary drivers of its diffusion.
Radiologists’ perception of CAD and double reading may relate to individual clinical practice in several ways. First, the perception that CAD takes less time than double reading may have negative implications if radiologists do actually shorten interpretation time of pre-CAD lesion detection (hence an over-reliance on CAD for lesion detection), because the overall performance of CAD is likely to suffer using this approach. Second, CAD use involves the same radiologist as both the first and second reader. With double reading the second interpreter is another radiologist, and may even include a third-radiologist for arbitration interpretation as in Europe. Double reading, especially with consensus may offer an important opportunity, absent from CAD, for radiologists to learn about the clinical decision making process by directly observing the practice of their peers. Finally, the most favorable perceptions of double reading were strongly related to protection from malpractice suits. Given that breast imaging is one of the highest litigation areas25
, this type of reassurance may be very positive for radiologists. CAD and double reading represent tradeoffs for radiologists – with increased cancer detection rate, and reassurance to radiologists and patients to be weighed against increased recall rate, time taken, and profitability
The congruence of radiologists’ perceptions with evidence from the literature is encouraging for clinical practice. The majority of studies show an increase in cancer detection rate for both CAD3–6
and double reading.7–11
Of note, however, is that most of the additional cancers detected with CAD were ductal carcinoma in situ
Some studies of double reading show no increase in recall rate, especially if consensus reading is part of the protocol.11,27
In this study, academically-affiliated radiologists were more likely to have the most favorable overall
view of double reading, but not of CAD. This may reflect the greater opportunities for collegial conferring among academicians and a lesser reliance on technologies for clinical decision making, but this deserves further investigation.
Several limitations and strengths in this study should be noted. First, the distribution of radiologists in some perception classes was small, so the effect should be considered in light of the numbers of radiologists in the classes. Second, latent classes are almost always subject to heterogeneity, so we caution against over-interpretation. Third, we did not collect information on the specific CAD system used by radiologists, so a small potential for differences in perception related to CAD system was possible. Also, we know that methods of double reading can vary, which we did not explicitly address in this study. In a study of community radiologists’ practice patterns, about half of the facilities used a double reading method which considered the second radiologist’s reading final, while the other half reported a variety of methods.28
Therefore, a potential exists for perceptions we report to be based on different methods of double reading. Finally, we were not able to measure the transition of radiologists from double reading to CAD. We did, however, examine perceptions of CAD and double reading according to whether the radiologist used CAD and/or double reading, and found similar trends (data not shown). Strengths of the study include the community-based radiologist participation and geographic distribution of respondents. Also, our high response rate makes selection bias less likely to be prominent.
This survey study is important in understanding how radiologists are using technology in the U.S. and how they perceive technologies and existing protocols. The congruence of radiologists’ perceptions of CAD and double reading performance with evidence from the literature suggests appropriate dissemination of knowledge. This study also suggests that radiologists have a more positive view of obtaining help from a colleague vs. a computer algorithm, but that computer-based input may have more efficiencies and cost advantages. In the U.S., CAD has diffused rapidly, apparently without formal assessment of radiologists’ perceptions, at the same time that double reading has declined. Ultimately, perceptions of these two interpretive practices may influence how they are used, more than whether they are used. An important next step is to more fully isolate the clinical decision making aspects of radiologists’ perceptions and preferences for CAD vs. double reading. One way to do this would be to elicit radiologists’ perceptions and preferences under the scenario in which reimbursement for double reading is equal to that for CAD, or a scenario in which there is no reimbursement for either practice. Understanding radiologists’ views of CAD and double reading helps to make the tradeoffs more apparent and informs clinic practice patterns.