Rationale and Objectives
To assess the interaction between the availability of prior examinations and digital breast tomosynthesis (DBT) in decisions to recall a woman during interpretation of mammograms.
Materials and Methods
Eight radiologists independently interpreted twice 36 mammography examinations, each of which had current and prior full-field digital mammography images (FFDM) and DBT under a Health Insurance Portability and Accountability Act–compliant, institutional review board–approved protocol (written consent waived). During the first reading, three sequential ratings were provided using FFDM only, followed by FFDM + DBT, and then followed by FFDM + DBT + priors. The second reading included FFDM only, then FFDM + priors, and then FFDM + priors + DBT. Twenty-two benign cases clinically recalled, 12 negative/benign examinations (not recalled), and two verified cancer cases were included. Recall recommendations and interaction between the effect of priors and DBT on decisions were assessed ( P = .05 significance level) using generalized linear model (PROC GLIMMIX, SAS, version 9.3; SAS Institute, Cary, NC) accounting for case and reader variability.
Results
Average recall rates in noncancer cases were significantly reduced (51%; P < .001) with the addition of DBT and with addition of priors (23%; P = .01). In absolute terms, the addition of DBT to FFDM reduced the recall rates from 0.67 to 0.42 and from 0.54 to 0.27 when DBT was available before and after priors, respectively. Recall reductions were from 0.64 to 0.54 and from 0.42 to 0.33 when priors were available before and after DBT, respectively. Regardless of the sequence in presentation, there were no statistically significant interactions between the effect of availability of DBT and priors ( P = .80).
Conclusions
Availability of both priors and DBT are independent primary factors in reducing recall recommendations during mammographic interpretations.
Digital breast tomosynthesis (DBT) has been approved for clinical use with the expectation of improving the efficacy of screening and diagnostic mammography by increasing the conspicuity of imaged abnormalities . With the advent of DBT, recent publications have substantiated the possible impact of this technology on the interpretation of screening mammograms in terms of reducing recall rates while simultaneously increasing cancer detection rates, in particular that of invasive cancers . However, many studies did not include the availability of prior examinations during the interpretation; hence, potentially enhancing the effect of DBT by stressing the reference interpretation. Studies that included prior examinations when available did not report separately on the impact of DBT in the two groups, namely “with” and “without” the availability of priors. In the clinical environment, the vast majority of women have been screened previously, allowing prior examinations to be available for comparison. It is well known that the availability of prior examinations during the interpretation of screening mammograms reduces recall rates substantially by enhancing the ability of the observer to assess change over time, if any, while at the same time discard depicted abnormalities that clearly represent a variety of benign (and stable) findings . Recent prospective studies indicate that even with the availability of priors, recall rates decreased substantially when DBT is included in the examinations being interpreted . However, there are no studies we are aware of aimed at assessing the relative contribution of priors and DBT on the decision whether to recall women for diagnostic workup of a suspicious finding, or not, or on the interaction, if any, between these primary factors affecting decisions to recall a woman (or not) for a diagnostic workup.
In this preliminary (pilot) study, we performed a two-reading mode observer study to preliminarily assess the interaction between the two primary contributing components to the reduction in recall rates in women who had undergone mammography examinations previously. By design, the study used an enhanced set of cases (a stress test) for this purpose and represents a pilot to a pivotal study that we are in the process of preparing for.
Materials and methods
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Study Population
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Participating Radiologists
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Observer Study
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Data Analysis
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Results
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Table 1
Average Recall Rates for Different Subset of Cases for First and Second Readings
Subset_n_ × 8 First Reading Second Reading FFDM Only FFDM + DBT FFDM + DBT + Priors FFDM Only FFDM + Priors FFDM + Priors + DBT Recalls Recalls Recalls Recalls Recalls Recalls Average Rate_n_ Average Rate_n_ Average Rate_n_ Average Rate_n_ Average Rate_n_ Average Rate_n_ Cancer 16 1.00 16 1.00 16 0.88 14 1.00 16 1.00 16 1.00 16 Recalled benign 176 0.70 123 0.46 81 0.39 69 0.66 117 0.60 106 0.31 55 Not recalled 96 0.63 60 0.35 34 0.23 22 0.59 57 0.44 42 0.20 19 All noncancer 272 0.67 183 0.42 115 0.33 91 0.64 174 0.54 148 0.27 74
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Discussion
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Conclusion
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References
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