European Journal of Cardiovascular Medicine

Breast carcinoma is a major cancer in both developed and developing countries is a real threat challenging all efforts to screening, prevention and treatment aspects to reduce this cancer. The incidence of breast cancer is rising in India and is now the second most common cancer diagnosed in women after cervical cancer. It is estimated that by 2030 the number of new cases of breast cancer in India will reach just under 200,000 per year. It is fast becoming the number one cancer among urban women (1).

X-ray mammography is still the gold standard of investigational procedures for breast lesions. Digital mammography has improved diagnostics, especially in younger women and in denser breasts, and CAD (computer aided detection) can be of some help. However, every effort is necessary to raise the early cancer detection rate and thereby reduce the mortality rate. (2) The earliest sign of breast cancer is an abnormality depicted on a mammogram, before it can be felt by the woman or her physician. (3)

The sensitivity of mammography alone decreases with increasing parenchymal density. Numbers of missed cancers in very dense breasts have been reported to be as high as 52% - 76% (4); in analogue screening programs, up to 30% of detectable cancers were not detected.   There are numerous reasons for this, the most important being the structured or anatomical noise produced by the overlapping tissue structures in the 2D imaging of a 3D object. Misinterpretation of architectural distortion and asymmetrical density, fibroglandular tissue overlapping the cancer and obscuring the margins of the cancer leads to false negative results. False positive findings which may mimic cancer can also be a result of these summation artefacts. The diffuse growth pattern of some tumors with ill-defined borders present a special problem. Digital Breast Tomosynthesis (D.B.T.) is a three-dimensional imaging technique which provides an arbitrary set of reconstruction planes in the breast from a limited angle series of projection images acquired while the X-ray tube moves through an arc above the stationary detector (4).  The result is a 3D data set of the entire breast volume. The individual planes of interest‖ of a chosen slice, usually 1 mm, can be viewed separately from the rest of the image, thereby reducing the impact of anatomical noise.  The individual slice shows enhancement of a lesion, while there is a blurring of the out-of- focus information of the breast tissue. (2).

Digital breast tomosynthesis (DBT) is one technology being developed to improve detection and characterization of breast lesions especially in women with non-fatty breasts. DBT may be useful in both the screening and diagnostic evaluation. (5). Hence this study was undertaken to compare and evaluate the impact of Digital Breast Tomosynthesis (DBT) combined with Full Field Digital Mammography (FFDM) versus FFDM alone in the diagnosis and interpretation of benign and malignant breast lesions utilizing the BIRADS score and to correlate the findings with histo-pathological diagnosis and to assess the accuracy of breast lesion characterization particularly, architectural distortion using BIRADS criteria with FFDM combined with DBT versus FFD.

This was a prospective, longitudinal study conducted in the department of Radiodiagnosis in a tertiary hospital in Western India from January 2018 to December 2019. Ethical clearance was obtained for the study for the time period mentioned. 

Informed consent was taken from all patients for participation in the study. All patients presenting to the department with breast lesion or lump with suspicion of breast malignancy were evaluated with full field digital mammography (FFDM) and digital breast tomosynthesis (DBT). All cases with BIRADS of 4 or above based on FFDM and DBT were further advised to undergo biopsy which will be sent for histopathological investigation. The remaining patients (BIRADS less than 4) will be either subjected to follow up (by ultrasonography or mammography) for a period of 6 months to exclude breast malignancy.

Inclusion criteria:

1. Patients coming for routine mammography screening for breast malignancy.
2. Patients presenting with a breast lump or lesion with clinical suspicion of malignancy.

Exclusion criteria:

1. Pregnant and lactating women
2. Patients who have undergone any surgeries on the breast in the past.
3. Patients not giving consent.

The continuous variables were analysed by Unpaired t test. Categorical data was analysed using Chi square test.  p values < 0.05 will be accepted as indicative of statistically significant.

All patients included had already undergone routine mammography in CC & MLO Views followed by complete digital tomosynthesis in CC & MLO Views. All examinations were performed on ― MAMMOMAT INSPIRATION WITH PRIME TECHNOLOGY by SIEMENS mammography & tomosynthesis machine. Mammomat Inspiration with PRIME Technology results in up to 30% less dose, without compromising image quality. The widest tomo angle with 50° and 25 projections in this machine provides the perspective required for optimal depth resolution, and cannot be achieved with smaller angles. (https://www.siemens-healthineers.com/en-in/mammography/digital-mammography/mammomat-inspiration-prime).

Legends Of Figures:

Figure 1: Mammomat Inspiration with Prime Technology by Siemens Mammography & Tomosynthesis Machine.

After acquisition, the data from the projection images was used to reconstruct between 50 to 90 or 60- 120 (depending on the tissue bulk) parallel 2 to 3 mm-thick slices depending on the thickness of breast. Re-reporting was done as per ACR guidelines. First only mammography films were reported without looking into tomosynthesis, findings were recorded & BIRADS categorization was done. Then for the same patient mammography films were read with the help of tomosynthesis, combined findings were recorded & BIRADS categorization was done. Results obtained by reporting digital mammography without tomosynthesis were compared with the Digital mammography + tomosynthesis reports. Finally, these results were correlated with    pathological findings. The agreement between the diagnostic modalities is compared by calculating the kappa statistic with 95% confidence interval and by percentage agreement with 95% confidence interval. The sensitivity and specificity of the imaging modalities is calculated with 95% confidence intervals.  The confidence intervals for percentage agreement and sensitivity and specificity is calculated using Wilson efficient-score method, corrected for continuity. Sensitivities and specificities are compared using McNemar test. p values < 0.05 are accepted as indicative of statistical significance

The study included 141 participants with breast lesion or lump with suspicion of breast malignancy and also the patients undergoing routine screening.

In our study 141 patients were included, who were in range of 29 to 91 yrs. Majority were in the age group of 51-60 years.

The breast masses were characterized according to the ACR BI-RADS Atlas® 5th Edition. Majority of the breast mass with irregular shape turned out to be malignant on HPE correlation.

Out of 141 patients 40 showed calcification on mammography which were seen equally well on tomosynthesis.

Younger females (<50 years) have Type d breast and as the age increases the glandular tissue is replaced by fat that is type a in >70 age group. (p value <0.0005)

Table 1: Age of the participants with each type of breast density

* Significant at 0.05 level of significance. One way ANOVA test used

In screening population (total 59 patients) , the detected breast lesions (BIRADS >3) on FFDM and DBT, 33.9% were benign and 66.1% were malignant.

In diagnostic group (total 79 patients), the detected lesions (BIRADS >3) on FFDM and DBT, 27.8% were benign and 72.2% were malignant.

Table 2: Results of histopathology (HPE) [n = 138] in the participants in the diagnostic and screening groups [Frequency (Percentage)]

#Significance level is 0.05. Chi-square test used.

It was observed that, in most cases DBT did not change the BIRADS scoring however, its addition increased the diagnostic confidence among readers. On addition of DBT to FFDM it was observed there is down gradation of the BIRADS score from 4A to 3 in 8 cases. And upgradation of BIRADS score from 4A to 4B in 1 case, 4A to 4C in 7 cases and to 5 in 2 cases.

Table 3: Nature of the breast lesions on histopathology (HPE) for each BIRADS score on FFDM plus DBT [Frequency (Percentage)]

This is in concordance to the study by Divya Singla, Arvind K. Chaturvedi et al, (27) which showed BIRADS was upgraded and downgraded in 14 and 31 cases, respectively, with the addition of DBT to FFDM.  Therefore, the addition of the DBT to FFDM increases the reader confidence and improves the lesion characterization.

Statistically significant increase in sensitivity was seen with the addition of DBT to FFDM in BIRADS ≥ 4B and ≥ 4C  (P = 0.004).

Statistically significant increase in positive predictive value was seen with the addition of DBT to FFDM in ≥ 4A.

Table 4: Diagnostic measurements - Positive Predictive value and Negative Predictive value for FFDM and FFDM plus DBT

Sensitivity of FFDM versus FFDM plus DBT in different breast densities is statistically significant in type b, c, d for BIRADS ≥ 4B and ≥ 4C. that is the detection rate of  BIRADS  ≥ 4B and ≥ 4C  lesions is improved on addition of DBT to FFDM.

Table 5: Comparison of sensitivity of FFDM versus FFDM plus DBT in different breast densities

There is no statistically significant increase in the specificity of lesion detection in different breast densities on addition of DBT to FFDM.

Table 6: Comparison of specificity of FFDM versus FFDM plus DBT in different breast densities

In both diagnostic and screening groups, significant increase in sensitivity, positive predictive value (P < 0.05) was seen with the addition of DBT to FFDM.

Table 7: Comparison of Negative predictive value of FFDM versus FFDM plus DBT in different breast densities

Increase in cancer detection rates by addition of DBT to FFDM was not statistically significant.

4 cases are shown from

Case 1) 2D Mammographic images [(a) & (c) magnified view of (a)] in CC view show microcalcifications in right breast laterally which are seen equally well on Tomosynthesis images in CC view [(c) & (d) magnified view of (c).