The role of breast imaging radiologist is very important as cancer breast is the most common malignancy in both developing and developed countries, so mammography remains the gold standard imaging in screening and early detection [2].
As a result of the 3D imaging capabilities of tomosynthesis, it plays an important role in screening and diagnosis of breast lesions, alleviating the limitation of mammography in masking cancers by dense breast tissue [3]. Tomosynthesis provides better imaging quality and accuracy in detection and classification of the lesions [4].
Ultrasonography is used in conjugation with mammography in detection and assessment of breast lesions as it is an inexpensive, noninvasive and non-ionizing imaging modality. However, it is operator dependent and image evaluation should be done during the procedure [5].
Nowadays, ABUS is used for breast evaluation, as it is an operator-independent US imaging with a high-resolution transducer [5].
The study of Poplack et al. [6], which included 98 women with abnormal mammography, had compared mammography with tomosynthesis in image quality and recall rates of screening. The results reported that tomosynthesis has superior or comparable image quality to that of mammography and reduces the recall rate when used with digital screening mammography [6].
Andersson et al. [7]’s study, in Canada on 36 patients, compared the breast cancer visibility in one-view tomosynthesis to cancer visibility in one- or two-view digital mammography (DM). The results indicated that the cancer visibility on breast tomosynthesis (BT) is superior to DM, which suggests that BT may have a higher sensitivity for breast cancer detection [7].
A comparison had been made in a study done by Gennaro et al. [8] in Italy, between the full-field digital mammography (FFDM) and the clinical performance of digital breast tomosynthesis (DBT), which showed that the clinical performance of tomosynthesis in one view at the same total dose as standard screen-film mammography is not inferior to digital mammography in two views [8].
Hakim et al. [9] examined 25 females and compared DBT to the additional mammographic views in different lesions characterization, asymmetries and architecture distortion and concluded that DBT could be an alternative to additional mammographic views in most patients.
Spangler et al. [10] proved in a study done on 100 patients that the FFDM is still more sensitive than digital tomosynthesis in detection and characterization of calcifications.
However, a study made by Zhang et al. [11] on a large sample (182) reported that tomosynthesis had more diagnostic accuracy for non-calcified lesions in comparison with additional mammographic views.
Teertstra et al. [12] study was done in the Netherlands on 519 cases and proved that tomosynthesis can be used as an additional technique to mammography in patients referred with an abnormal screening mammogram or with clinical symptoms.
A study was done by Kim et al. [13] on 119 patients, which proved that digital breast tomosynthesis could detect similar lesion characterization performance compared to that of US for the lesions depicted on digital mammography (DM).
The retrospective study of Krammer et al. [14] proved that digital breast tomosynthesis (DBT) could improve the preoperative breast cancer staging in dense breast patients compared to conventional mammography alone. However, limitations have to be expected in the case of invasive lobular carcinoma [14].
Kelly et al. [15] compared the mammographic diagnostic performance to that of the automated breast ultrasound (ABUS) in dense breast and resulted in significant cancer detection improvement by ABUS compared with mammography alone.
Another study retrospectively depicted that ABUS had higher performance in detecting malignant lesions with their surrounding changes than benign lesions [16].
The study of Lin et al. [17], which was performed in China on 81 cases, compared the clinical utility of ABUS against HHUS in breast lesion detection and proved that ABUS had high diagnostic accuracy, operator independence and better lesion size.
A similar study was conducted on 175 patients, and it evaluated the differences in the diagnostic values of the conventional handheld B-mode ultrasound (HHUS) and automated breast ultrasound (ABUS) for benign and malignant breast masses and compared it with the final pathologic findings. It showed that overall ABUS and HHUS do not differ in diagnostic accuracy for the differentiation of malignant or benign breast masses [5].
Giuliano et al. [18] study was performed in 3418 asymptomatic women with mammographically detected dense breasts and proved that ABUS could be used in conjunction with mammography in the dense breast screening population study.
Giger et al. [19] compared the performance of breast cancer detection using full-field digital mammography (FFDM) alone and using FFDM with ABUS. The study included 185 cases, 133 non-cancers and 52 biopsy-proven cancers. They concluded that combining mammography with ABUS compared with mammography alone had significantly improved readers’ detection of breast cancers in women with dense breast tissue without substantially affecting specificity [19].
The current research was a prospective study conducted on 38 patients presenting with dense breast masses either discovered clinically or discovered by mammographic examination as a part of the early detection program. They have been evaluated by means of digital breast tomosynthesis and automated breast ultrasound, 38 masses were detected in the 38 patients, and pathological confirmation was done in most masses (n = 31/38) and ultrasonography confirmation in the rest (n = 7 /38): simple cysts, fat containing lesion (hamartoma) and fibroadenomas.
Image data analysis from both automated ultrasound and tomosynthesis was performed by two radiologists independently, and the findings were reported as per the morphology descriptors used in the BIRADS lexicon. The data were interpreted as regards the location, extension of the lesions, mass number, shape, margin, skin retraction and thickening, and the presence of calcification, and a final score was given according to the BIRADS assessment categories. The specificity and sensitivity of each modality in characterization and detection of breast lesions were detected.
Our study included 38 females presenting with different types of breast lesions.
Thirty-eight masses were detected, among which 14 were benign (n = 14/38) and 24 were malignant (n = 24/38).
Histopathology of the masses was reached using different techniques such as core biopsy (n = 24), FNAC (n = 6) and excisional biopsy (n = 2). The rest of the masses (n = 6/38) were confirmed by their characteristic sonographic appearances: anechoic simple cysts and mixed echogenicity hamartoma.
Different pathologies were identified, some of which were benign such as fibroadenoma, simple cysts, hamartoma, inflammatory mastitis and focal fibroadenosis. The latter was falsely diagnosed by tomosynthesis as a mass due to its circumscribed margin.
Others were malignant, such as invasive duct carcinoma (commonest type of malignancy in our study 28.9%), invasive lobular carcinoma, invasive mammary carcinoma and duct carcinoma in situ. The latter was the most difficult to detect in this study due to the subtle changes of ductal dilatation.
Among our cases, two were metastatic breast masses. One of them was female patient who gave a history of cancer colon; the mass appeared irregular with speculated margins, so malignant nature was suspected, then core biopsy was done, and histopathology revealed metastatic adenocarcinoma. On the contrary, the other metastatic breast mass was circumscribed with no available data regarding any history of malignancy, and histopathology revealed metastatic melanoma.
Six masses were diagnosed by their characteristic sonographic findings; 2 of them were simple cysts with the characteristic anechoic nature and posterior enhancement, and 1 was hamartoma with their special imaging features (fat containing mass which resembles breast within the breast), and 3 were fibroadenomas with characteristic hypoechoic oval lesion.
According to the newest BIRADS lexicon criteria in the description of malignant masses, 22 masses were irregular on both modalities and were proved to be malignant, yet tomosynthesis underestimated one case since it showed rounded mass (normally to a benign descriptor). On the other hand, fine speculation was detected on automated ultrasound images and proved by core biopsy to be malignant in nature.
We found out that the sensitivity of ABUS was 87% regarding the malignant lesion shape characterization in comparison with tomosynthesis which showed 69.6% sensitivity.
Regarding the margins, 92.9% of the circumscribed masses were benign and 100% of the speculated masses were malignant in our study. Despite that three masses were circumscribed on both modalities, their histopathology results proved them malignant. This confirmed that a single criterion was not enough for radiologists to reach a correct final diagnosis. Tomosynthesis showed 87.5% sensitivity, while ABUS showed 100% sensitivity in the current study.
Regarding the number of masses, tomosynthesis detected multiple lesions in about 14 out of 18 cases, while automated ultrasound was able to detect the whole 18 cases.
Although most of the masses were seen on both modalities, tomosynthesis missed one case, yet it was visible by automated ultrasound as a very small irregular mass.
ABUS showed 23.7% in the category of detecting mass extension, while tomosynthesis showed 31.6%.
For the skin thickening and retraction, tomosynthesis was sensitive in 26.3%, while automated ultrasound was sensitive in 28.9%.
As regards the final BIRADS score given for both modalities, tomosynthesis showed an accuracy of 92.1% in characterization of malignant masses with an accuracy of 100% in benign masses; on the other hand, automated ultrasound showed 100% accuracy in characterization of malignant masses with 100% accuracy in benign masses.
In summary, we detected in the current study that the sensitivity of tomosynthesis in characterization and detection of breast lesions was 87.5%; both the specificity and PPV were 100%, while the negative predictive value was 82.4%. On the other hand, ABU showed 100% in all the sensitivity, the specificity, PPV and NPV.
Our study succeeded to prove that ABUS is a reliable screening and diagnostic imaging tool. It could detect different breast lesions and abnormalities whether benign or malignant, showed improvements in cancer detection rates, decreased the need for further assessments, reduced the false positive rates, and showed superior performance compared to digital mammography, in lesion detection, characterization, tumor margins and extent, multifocality and multi-centricity of the malignant lesions, and image quality, especially in dense breast lesions.
