Breast Arterial Calcifications on Mammography among Patients Attending the Radiology Department in a Tertiary Care Centre: A Descriptive Cross-sectional Study

ABSTRACT Introduction: Breast arterial calcifications are common mammographic findings which are associated with coronary artery disease. The aim of this study was to find the prevalence of breast arterial calcifications in women presenting for mammography in a tertiary care centre. Methods: This descriptive cross-sectional study was performed in the Department of Radiology, in a tertiary care hospital after taking ethical clearance, Reference number 352(6-11)E-2, 077/078, data was collected from Syngovia database from March-June 2021 which included 1614 mammograms. Convenience sampling was done and mammograms evaluated for presence of vascular or non-vascular calcification. Further, vascular calcification was graded. Data was entered in Statistical Package for Social Sciences version 25. Point estimate at 95% Confidence Interval was done, and frequency and proportion were calculated. Results: The prevalence of breast arterial calcification was 188 (11.6%) at 95% Confidence Interval (10.03-13.2). The mean age of women included in this study was 48.42±9.55 years with the largest number of patients in the age group 40-49 years, 682 (42.3%), and least in the age group 80-89 years, 3 (0.2%). All patients in the age group 80-89 years, 3 (100%) had vascular calcifications followed by 70-79 years group, 22 (57.5%) and none in patients younger than 30 years. Conclusions: We found an increase in the number and grade of vascular calcifications in breasts with the patient's age. When present breast arterial calcifications must be mentioned in mammogram report. Identification of such calcifications on mammogram should prompt further screening for atherosclerotic disease.


INTRODUCTION
Mammograms are commonly done for screening of breast cancer or evaluation of breast symptoms. In Nepal, diagnostic mammograms are done more often than screening due to lack of awareness and absence of guidelines facilitating screening studies. 1 Breast arterial calcifications (BAC) represent arteriosclerotic changes occurring in medium sized arteries supplying the breast.
Different calcifications, including vascular, are often seen in mammograms, but being unrelated to breast disease, are often not reported. Various studies have shown an increased risk of Coronary Artery Disease (CAD) with BAC. [2][3][4] In addition to CAD, other risk factors like age, Diabetes Mellitus, CAD risk factors, pregnancy, lactation and renal impairment are also associated with BAC. 5 Reporting BAC may help identify group of patients at higher risk of CAD and prompt appropriate and timely evaluation.
The aim of our study was to find the prevalence of BAC in women presenting for mammography in our tertiary care hospital. Adding a non-response rate of 10%, the sample size was 1,174. However, 1614 samples were included in the study.
Two basic projections (cranio-caudal & mediolateral oblique) of the breasts were obtained with the MAMMOMAT Fusion mammographic unit. These mammograms available in Syngovia work station YLXRO19095 database were evaluated by radiologists with more than 10 years of expertise. The pattern and extent of calcification was evaluated visually in the workstation using appropriate magnification tools. Presence of calcification of any type was noted and classified as benign vascular, benign non-vascular or malignant. Vascular calcification was further graded as follows, which was adapted from the previously proposed scoring systems. 6

RESULTS
The prevalence of BAC in our study was found to be 188 (11.6%) at 95% CI (10.03-13.2).

Figure 2. Bar diagram of the distribution of grades of BAC according to age group.
There was an increase in prevalence of BAC with increasing age, with no calcifications in less than 29 years of age and all patients older than 80 years having BAC (Figure 3).We found increase in the number and grade of BAC with age.

DISCUSSION
BAC more often involves calcification in the tunica media and represents arteriosclerosis than atherosclerotic intimal calcification. These are fine initially, becoming a more definite linear or tram track followed by dense, coarse and confluent obscuring the vessel lumen. 8 It may be difficult to differentiate medial or intimal calcification on mammogram. Studies have shown a higher incidence of BAC in patients with renal disease, atherosclerotic coronary artery disease, CAD risk factors, diabetes as well as previous history of pregnancy and lactation. 5,[9][10] McLenachan, et al. concluded that while absence of BAC has a high negative predictive value for ruling out CAD, the diagnostic accuracy to predict the same is limited. 11 Some other studies do not show any association between BAC and CAD.
We had more patients with grade 1 calcification than grade 2 or 3 and an increasing number and grade of BAC with age, with all those above 80 years of age having grade 3 BAC. The increase in presence and grade of BAC with age in our study is consistent with most other studies.
The prevalence of breast calcifications in our study of any type, that is, vascular or non-vascular was about 522 (32.3%) and BAC was 188 (11.6%). Studies have shown the prevalence of BAC generally varies from 9-17%, being higher in older patients. 3 A similar study which had population ranging from 49-70 years, showed prevalence similar to our study of 11%, and found a positive association with age, pregnancy and lactation. However, they did not find any relation between BAC and atherosclerotic risk factors. 12 The prevalence of BAC was 14.1% in another study, including patients from 40-93 years of age, with increasing trend with age. 2 Higher prevalence of 20% was seen in a study conducted in Nigeria. 3 13 Compared to our study, while most others have greater BAC prevalence, some show a lower prevalence, minimum being 3%. The slightly lower prevalence in our study could be due to a greater number of younger patients with diagnostic indications more often than screening mammograms. 1 We had a few patients younger than 40 years, who either had high risk factors for breast carcinoma or another diagnostic indication.
While such vascular calcifications are often seen on mammography, being unrelated to breast cancer, they are not always mentioned in the report. An interesting study found that patients and preventive cardiologists prefer BAC being reported in mammogram studies done for other indications. 14 It is important to make a note on this incidental finding. 15

CONCLUSIONS
Since there is an increase in prevalence and grade of vascular calcification with age. We recommend that the benign vascular calcification when present must always be reported in the mammogram report, as such patients may have higher risk of atherosclerotic disease.
Conflict of Interest: This study was done as a part of the University Grant Commission project FRG-HS-3 075-76.