Discussion
Mammography was still the best screening imaging modality for the women worldwide. The decision of starting screening should be the result of personalized discussion between the female patient and her provider, including both the benefits and risks of routine screening [7].
3D digital breast tomosynthesis (3D DBT) was a new screening and diagnostic technique in breast evaluations with a high promising role in increasing the sensitivity and specificity of digital mammography (DM) [8].
Women with dense breast were usually at high risk of developing breast cancer as the increase density might mask the radiological signs of cancer, while on the other hand cancers were clearly visible in fatty breasts on mammogram. So the detection of breast carcinoma might be complex and in need of multiple imaging modalities [2].
3D DBT was one technology being developed to improve both the detection and characterization of the breast lesions mainly in females with non-fatty breasts as it was expected to overcome the limitations of mammography caused by overlapping of both normal and pathological tissues during the standard two-dimensional (2D) imaging projections [7].
The known benefits of 3D DBT improved in both screening sensitivity and detection of lesion size as well as lesion characterization, which in turn resulted in decreasing the recall rates [5].
Our aim of study was to detect and prove the role of 3D digital tomosynthesis in evaluation of BIRADS 3 breast lesions.
Bunovic et al. performed a prospective study in which 3D DBT was performed in 360 DM-detected BIRADS3 lesions. The radiologist independently reads DM and 3D DBT. Only 22.8% of BIRADS 3 lesions (82/360) did not change their BIRADS after tomosynthesis, while 77.2% (278/360) were re-classified according to the BIRADS system. TS “down-staged” BIRADS 3 lesions to BIRADS 1 or 2 categories in most of the cases (263/360) and “upstaged” 15 cases to BIRADS 4 and 5 [8].
Helyie subjectively compared 3D DBT when characterizing known masses, architectural distortions, or asymmetries. The study included the mammography of 25 women with known masses. After review of the examinations, radiologists rated their relative preference in terms of classifying the finding in question twice; one time when aided by the additional views and another when aided by 3D DBT. The diagnostic BIRADS rating of both examinations were correlated. They found that DM and 3D DBT (combined) were perceived to be better for diagnosis in 50% of cases. They concluded that 3D DBT might be an effective alternative to the additional mammographic views in most cases mostly if the presentation of the concerned lesion was not calcification [5].
Skaane verified that DBT added more in defining the shape and margins of breast lesions by decreasing the overlapping tissue, and as a result the ability to differentiate between superimposed tissue and breast lesions would be improved [9].
STORM-2 demonstrated a significant increase in cancer detection rate (CDR) when DBT was added to 2D FFDM (8.5 per 1000 2D+DBT, 6.3 per 1000 2D FFDM). This improvement was maintained and actually slightly increased with s2D+DBT (8.8 per 1000). Incremental CDRs over 2D alone were also similar between s2D+DBT (+ 2.5 per 1000) and 2D+DBT (+ 2.2 per 1000). The most significant improvements in cancer detection were seen in women < 60 years of age and women with dense breasts. As biennial screening is the standard in European screening programs, the CDRs reported in STORM-2 are higher than typical North American practices [10].
Aujero et al.’s results showed a slight increase in cancer detection from 2D FFDM (5.3 per 1000) to 2D+DBT (6.4 per 1000), which was maintained with s2D+DBT (6.1 per 1000). Notably, the percentage of invasive cancers detected with s2D+DBT was significantly higher than 2D and 2D+DBT (s2D+DBT 76.5%, 2D 61%, 2D+DBT 61.3%; p < 0.01), without a loss in in situ cancer detection. This was thought to reflect a learning curve of using DBT, as the s2D+DBT studies were interpreted after some years of experience with DBT [11].
In our study, 60% of the BIRADS 3 lesions changed their BIRADS by 3D DBT 48.3% were down staged to BIRADS 1 and 2, and 11.7% were “upstaged” to a higher BIRADS. Forty percent of the BIRADS 3 lesions did not change their BIRADS. So 3D DBT significantly reduced the need for additional mammographic views and as well the frequent follow-up studies as it gave better characterization for all BIRADS 3 lesions and reduced the stress levels in women. DBT did not show any false-negative results in our study and it did not miss any cancers.
So the ability to scroll through the three-dimensional data set for a particular view helps in eliminating the overlap of tissues seen in two-dimensional images and better resolution of the internal contents leading to better diagnostic capabilities.
Though the primary role of screening mammography was early detection of breast cancer, tomosynthesis came in with numerous advantages that included the high specificity in benign breast lesions detection and as well as categorization of benign versus malignant lesions. This in turn would reduce the need for additional time-consuming imaging such as special mammographic views or sono-mammography thereby increasing the efficacy of the test by reducing the additional radiation dose, time, and money. At the same time, it reduced the patient’s anxiety by avoiding unnecessary recalls.
Therefore, according to our study results, we highly recommend tomosynthesis as a diagnostic algorithm tool in patients with mammography-detected BIRADS 3 lesions (Figs. 4, 5, 6, 7, and 8).