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Strain Elastography in differentiating benign versus malignant breast masses: Demystifying its role
*Corresponding author: Aanchal Bhayana, Departments of Radiology, Vardhman Mahavir Medical College and Safdarjung Hospital, Ring Road, New Delhi, India. aanchalbhayana@gmail.com
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Received: ,
Accepted: ,
How to cite this article: Bhayana A, Khanna G, Bagri N. Strain Elastography in differentiating benign versus malignant breast masses: Demystifying its role. Indian J Breast Imaging. 2026;4:4-12. doi: 10.25259/IJBI_32_2025
Abstract
Objectives:
The purpose of our study was to evaluate and compare the diagnostic accuracies of strain elastography versus conventional ultrasound in differentiating benign and malignant breast masses, using histopathology as the gold standard. Our study also adds to the literature by describing strain elastography features of a few unusual entities, namely, multiple juvenile fibroadenomas, tubercular mastitis, and secretory carcinoma in an adolescent girl.
Materials and Methods:
Both conventional ultrasound and strain elastography were performed in solid breast masses in 100 female patients; the largest mass was evaluated in patients with multiple lesions. Breast Imaging Reporting and Data System (BIRADS) criteria were used for conventional ultrasound diagnosis. Strain elastography parameters used for the diagnosis of malignancy were color coding (Tsukuba score ≥ 4), size ratio >1, and strain ratio >3.85. The conventional ultrasound and strain elastography diagnoses were both compared with histopathology. Diagnostic accuracy and receiver operator characteristic (ROC) curve analysis with area under the curve (AUC) were calculated for both techniques.
Results:
Conventional ultrasound had a specificity of 81.5%, Positive predictive value (PPV) of 82.14%, and AUC (ROC) 0.938. Strain elastography using a strain ratio cut-off of 3.85 (by ROC curve analysis) showed specificity of 88.89%, PPV of 88.46%, and AUC (ROC) 0.977. Using histopathology as the gold standard, strain elastography revealed a statistically significant improvement in specificity with p < 0.05.
Conclusion:
The complementary use of strain elastography improves diagnostic accuracy of conventional ultrasound and should, therefore, be recommended for inclusion in the routine breast ultrasound protocol, thereby reducing the number of unnecessary benign breast biopsies.
INTRODUCTION
Breast cancer is the most common malignancy in women globally and is among the predominant cancers in women both in the developed and developing world.[1] Although prevention might help in some risk reduction, these preventive strategies have not been proven to be efficient in eliminating the major burden of breast cancer in developing countries.[2,3] The diagnosis of breast cancer depends on self-breast examination, imaging, and pathology evaluation. Imaging forms a backbone for documentation of breast diseases, and although current modalities, namely Mammography, Sonography, and Magnetic resonance imaging (MRI), have high sensitivities for detection, they lack high specificity rates.[4-8]
The limitations of currently available imaging modalities, together with the clinical aim of obviating delayed diagnosis, lead to high biopsy rates. Various authors have reported that a large number of breast biopsies are being executed on benign lesions and are classified as “unnecessary”.[8-11] Newer Ultrasound (US) techniques have therefore been evolving, and commendable amongst these are Elastography, using Strain Elastography (SE) and Shear Wave Elastography (SWE).[12-17] SE utilizes free-hand compression, which is more economical and widely available, as compared to SWE.
The purpose of this retrospective study was, therefore, to evaluate the diagnostic accuracy of SE and to compare its diagnostic accuracy versus Conventional US, in differentiating benign and malignant breast lesions, using histopathology diagnosis as the gold standard. Our study also aims to add to the literature by describing SE features of a few unusual entities, namely, bilateral multiple juvenile fibroadenomas, Tubercular mastitis, and Secretory Carcinoma in a young adolescent girl. To the best of our knowledge, SE features of these entities have not been documented earlier.
MATERIALS AND METHODS
Study design and setting: The institutional/review board approved this retrospective study.
Patients and inclusion criteria
The study was carried out on 100 female patients having solid breast masses on Conventional US and in whom SE was performed from the year 2017 to 2025. The Histopathology (biopsy) reports of all these 100 breast masses were finally correlated with the Conventional US and SE findings.
Exclusion criteria
a). Cystic breast masses on conventional US.
b). Solid breast masses on conventional US images for which SE could not be performed.
c). The solid breast masses images for which histopathology reports are not available.
Conventional US
Following clinical evaluation, bilateral breast US was performed in each patient, using a US scanner, Phillips iU22 xMatrix (USA), with a linear-array transducer of 17-5 MHz frequency. Sonographic features evaluated were quadrant location, number of lesions, distance from nipple, depth from skin, size, shape, margins, echogenicity, posterior acoustic phenomenon, calcifications, nipple retraction, ductal dilatation, and skin thickening. The US Breast Imaging Reporting and Data System (BIRADS) was used to classify the lesions detected on sonography.[18]
SE was performed by two radiologists, one with five years of experience and the other with one year of experience, for better reproducibility. A US scanner, Phillips iU22 xMatrix (USA) with SE capability, was used. A linear array transducer of 17-5 MHz and an advanced breast tissue-specific imaging preset were utilized for the study. The patient position for Elastography was similar to Conventional US, and the same depth, focus, and gain settings were used, as for conventional imaging. Elastography images were generated by the free-hand manual compression technique as described by Itoh et al.[13] The target lesion was compressed vertically by a linear high-frequency transducer perpendicular to the lesion under light pressure. The elasticity image was displayed with the color mapping for each pixel, according to the strain in the region of interest. Split screen/Side by Side imaging mode was used to display the identical images on Conventional US and Elastography.
Interpretation
The elasticity image of the detected lesion was evaluated using color coding, size ratio, and strain ratio (SR) as the assessment parameters, and final analysis was done as per the criteria described by previous investigators.[10,13,14,17]
Color coding
In our study, a scale from Blue (greatest strain: softest) to yellow and green (average strain: Intermediate component) to Red (No strain: Hardest component) was used. An elastic score, namely the Tsukuba score, was assigned based on the color coding, as described by Itoh et al.[13]
Score 1-even strain for the entire hypoechoic lesion
Score 2-strain in most of the hypoechoic lesions, with some areas of absent strain
Score 3-strain at the periphery of the hypoechoic lesion with sparing of the center
Score 4- absent strain in the entire hypoechoic lesion
Score 5- absent strain in the entire hypoechoic lesion or its surroundings
Size ratio
A length assessment was performed to compare the lesion size on the conventional US with that on the elastogram, as described for the first time in the literature by Hall et al.[14] The lesion was measured at the same position on both the B-mode image and the elastogram. The use of the mirror function was utilized, in which the lesion was measured on the B-mode image, and the size measurement was automatically depicted on the elastogram image, being displayed side by side. (Size Ratio = Maximum width of lesion on the elastogram image/maximum width on B-mode image). The ratio was determined to be greater/lesser/equal to 1, as per Barr et al.[10]
Strain ratio
An SR measurement compares the strain in two manually selected regions of interest (ROIs) on the elastograms.[9] One ROI was placed in the focal lesion, and the reference ROI was kept in the surrounding normal tissue, preferably at the same depth as the lesion. The SR is automatically calculated by the elastography software and yields the average strain in the reference (normal) area divided by the average strain in the lesion. The higher the strain, the higher the likelihood of malignancy.[16-19]
Pathology
A US-guided core needle biopsy was done in all 100 patients under complete aseptic precautions. Finally, the results of Conventional US and SE were compared with the pathology diagnosis.
Statistical analysis
The diagnostic accuracy of SE and Conventional US was calculated using Specificity, Sensitivity, Positive Predictive Values (PPV), and Negative Predictive Values (NPV). Receiver Operator Characteristic curve (ROC) analysis was done, and the Area Under Curve (AUC) was calculated and compared for both Conventional US and SE using pathology diagnosis as the gold standard. A p-value < 0.05 was considered statistically significant.
RESULTS
Of the 100 patients included in the study, the final diagnosis at pathology was of a benign lesion in 54 masses and a malignant one in 46 masses. Conventional US features were suggestive of benign disease (BIRADS 2) in 44 breast masses, malignant disease (BIRADS 5) in 46 breast masses, and ten masses were observed to be of indeterminate nature (BIRADS 4). Of these ten indeterminate masses, SE suggested a benign mass in four patients, and six masses depicted malignant features on Strain Elastography. The findings are summarized in Table 1.
| BIRADS category on conventional ultrasound | No. of masses | Strain elastography diagnosis | No. of masses | Pathology diagnosis benign | Malignant | No. of masses |
|---|---|---|---|---|---|---|
| BIRADS 2 | 44 | Benign | 44 | Fibroadenoma galactocele breast lipoma | - - - |
41 2 1 |
| BIRADS 5 | 46 | Malignant | 46 | - - - |
Infiltrating ductal carcinoma Secretory carcinoma mucinous carcinoma | 44 1 1 |
| BIRADS 4 | 10 | Benign Malignant |
4 6 |
Tb mastitis giant fibroadenomas juvenile fibroadenoma phyllodes tumor galactocele rapidly growing fibroadenomas | 2 2 1 2 3 |
BIRADS: Breast Imaging Reporting and Data System
The 44 breast masses, which were observed to have benign features on Conventional US (BIRADS 2), showed features of benign disease on SE [Table 1]. These were confirmed on biopsy to be fibroadenoma in 41 [Figure 1], galactocele in two [Figure 2], and breast lipoma in one mass [Figure 3]. Conventional US features were suggestive of malignancy (BIRADS 5) in 46 breast masses, and SE depicted malignant features in all, with final confirmation on biopsy [Table 1].
Out of these 46 breast masses, 44 masses were diagnosed as infiltrating ductal carcinoma [Figure 4], one mass as secretory carcinoma [Figure 5], and one as mucinous carcinoma [Figure 6].
Conventional US revealed indeterminate masses of the BIRADS 4 category in ten patients [Table 1]. These ten indeterminate masses were further evaluated on SE for better characterization, and their imaging features are enumerated below.
In one patient, a 16-year-old adolescent girl, who presented with a clinical diagnosis of bilateral multiple juvenile fibroadenomas, Conventional US showed multiple heterogeneously hypoechoic masses in both breasts. However, one of these lesions at 10-11 o’clock in the left breast appeared irregular and had spiculated margins, suggesting a BIRADS 4 lesion [Figure 7a]. On Strain Elastography, this lesion showed a mosaic pattern on a color-coded image with an elasticity score of 2, a size ratio of 1, and an SR of 6.13 [Figure 7a and b]. Elasticity score of 2 and a benign size ratio favored diagnosis of a benign lesion; however, a high SR favored malignancy. Finally, pathology confirmed this suspicious mass to be a rapidly growing fibroadenoma, in a case of bilateral multiple juvenile fibroadenomas [Figure 7c].
In two patients, referred to with a clinical diagnosis of phyllodes tumor, Conventional US showed a BIRADS 4 lesion in both, suggesting a diagnosis of phyllodes tumor. [Figure 8a] shows conventional US features of one of these two patients. In this patient, SE showed a color-coded elasticity score of 4 and an SR of 3.94 [Figures 8b and c]. High SR in the mass favored malignancy. However, pathology finally confirmed this mass to be a benign phyllodes tumor [Figure 8d]. In the second patient, SE revealed similar features. This mass was also confirmed to be a benign phyllodes tumor on pathology. In both patients, on strain elastography, the size ratio could not be evaluated, owing to their large sizes, which could not be depicted in their entirety in the split elastography screen.
Three patients, who were referred with a clinically suspected diagnosis of chronic galactocele, Conventional US showed well-defined, smoothly marginated, heterogeneously hypoechoic lesions with areas of dense calcifications, with posterior acoustic shadowing in all. Conventional US features of one of these three patients are shown in Figure 9a. On Strain Elastography, this mass showed a size ratio of 0.87, with a color-coded elasticity score of 4 and an SR of 4.2 [Figures 9a and b]. The high SR could be attributed to the presence of dense calcifications within the mass. The high elasticity score and high SR in this mass favored malignant etiology. However, on pathology, this mass was diagnosed as a galactocele [Figure 9c]. The other two patients also depicted similar features on Strain Elastography, and were also confirmed to be galactoceles on pathology.
Two patients were referred with a clinical diagnosis of chronic abscess. In one of these patients, a 25-year-old female, Conventional US showed a well-defined heterogeneously hypoechoic mass lesion with focal angulation and tubular projection into the adjacent breast parenchyma, suggesting a BIRADS 4 lesion [Figure 10a]. SE revealed a mosaic pattern on a color-coded image with an elasticity score of 2, a size ratio of 0.99, and an SR of 2.21 [Figure 10a and b]. These elastography features suggested a benign lesion, which was further confirmed on pathology to be tubercular mastitis [Figure 10c]. In the second patient, similar features were observed on Strain elastography. These elastography features were suggestive of a benign diagnosis and were confirmed to be tubercular mastitis on pathology.
In two patients, who presented rapidly enlarging masses with a clinical suspicion of malignancy, Conventional US revealed well-defined heterogeneously hypoechoic masses with lobulated margins and focal microlobulations in both, suggesting a BIRADS 4 lesion. In both of these masses, SE depicted benign size ratios, low SRs, and low color-coded elasticity scores. These SE features favored the diagnosis of a benign mass, and pathology finally confirmed these masses to be rapidly growing fibroadenomas.
Table 2 shows the diagnostic accuracy of Conventional US and SE using color coding based on elasticity score, size ratio, and SR. Considering Conventional US BIRADS 2 category as benign and BIRADS 4 & 5 categories as malignant, the sensitivity of Conventional US, for malignancy detection reached 100%, with specificity, NPV, and PPV of 81.5%, 100%, and 82.14% respectively. For Strain elastography, using color-coded elasticity scores of 1-3 as benign and 4-5 as malignant, the sensitivity for malignancy detection reached 100%, with a specificity of 81.48%, PPV of 82.14%, and NPV of 100%. When the breast masses with a size ratio of less than or equal to 1 were designated as benign and masses with a size ratio of more than 1 as malignant, the sensitivity of Strain Elastography, for diagnosis of malignant lesions, reached 91.3%, with a specificity of 74%, NPV of 90.91%, and PPV of 75%. ROC analysis was done for SR to obtain a cutoff value for the differentiation of benign versus malignant solid breast masses. The cut-off value for SR for malignancy was estimated to be 3.85 in this study. Figure 11 shows the ROC curve for SR. Using the SR cut-off value of 3.85 as a predictor of malignancy, the sensitivity was found to be 100%, the specificity was 88.89%, the PPV was 88.46%, and the NPV was 100%.
| Parameter | Conventional Ultrasound (US) | Strain elastography (SE) | ||
|---|---|---|---|---|
| Color coding (elasticity score 1-3 as benign and 4-5 as malignant) | Size ratio (>1 as malignant and ≤ 1 as benign) | SR (3.85 as cut off) | ||
| Sensitivity | 100% | 100% | 91.3% | 100% |
| Specificity | 81.5% | 81.48% | 74% | 88.89% |
| PPV | 82.14% | 82.14% | 75% | 88.46 % |
| NPV | 100% | 100% | 90.91% | 100 % |
| AUC | 0.938 | 0.977 | ||
| p value | 0.04794 | |||
p value significant: <0.05. SR: Strain ratio, PPV- Positive predictive value, NPV: Negative predictive value, AUC: Area under curve.
Finally, the AUC, based on ROC analysis, was compared for both Conventional US and SE. Table 2 shows a comparison of the ROC curves of Conventional US and SE. The p-value for ROC analysis was found to be 0.04794 (<0.05), which is statistically significant.
DISCUSSION
A few investigators in the past have evaluated the diagnostic performance of Strain Elastography, using different parameters, namely, color-coded elasticity score, size ratio, and SR, for the characterization of breast masses.[7,9,10,13,14]
Our study is a large retrospective study, carried out in a tertiary care hospital, where 100 solid breast masses on Conventional US, in whom SE using color-coded elasticity score, size ratio, and SR were performed, were analyzed, and the results compared with histopathology diagnosis.
There is ongoing research for establishing the best cutoff values of SR for better differentiation of benign and malignant lesions. Most previous investigators have suggested SRs of >3 as suspicious for malignancy.[7,9] We found the SR cut-off value to be 3.85 in our study. Out of the three SE parameters used, SR showed the best specificity for differentiation of benign versus malignant breast masses, compared to color coding and size ratio. Using the SR cut-off value of 3.85, the specificity and PPV of SE were observed to be better at 88.89% and 88.46%, respectively, compared to those of Conventional US, which was 81.5% and 82.14%, respectively. The results of this study, showing a high specificity of SE, were in agreement with previous reports by Zhi et al, Garra et al., and Navarro et al.[7,16,20]
The highlights of this study are the documentation of SE features of a few unusual entities, namely secretory carcinoma in an adolescent female, rapidly growing fibroadenoma (in a case of bilateral multiple juvenile fibroadenomas), chronic galactocele, and tubercular mastitis. SE features of all these breast lesions, to the best of our knowledge, have not been published previously in the literature.
A rapidly growing fibroadenoma, in the case of bilateral multiple juvenile fibroadenomas, showed a mosaic color pattern with an elasticity score of 2, a benign size ratio (<1), and a high SR (>3.85). The low elasticity score and benign size ratio favored the diagnosis of a benign lesion. However, high SRs in these masses, due to their rapid growth, can simulate malignancy on imaging and therefore require pathology for final confirmation.
Phyllodes tumors showed a color-coded elasticity score of 4 and a high SR (>3.85). The size ratio could not be evaluated in these lesions, as they couldn't be depicted completely on the split elastography screen, due to their large sizes. High elasticity scores and high SRs in these masses mimic malignancy.
Chronic Galactoceles showed a low size ratio, with a color-coded elasticity score of 4 and a high SR (>3.85). The low size ratio in these masses favors a benign diagnosis. However, owing to the presence of dense calcifications, these lesions may falsely show high SRs and high elasticity scores, despite the absence of malignancy.
Breast tuberculosis is a rare entity that poses a great challenge to diagnosis both clinically and radiologically, as it mimics malignancy. Three types of breast tuberculosis -disseminated, nodular, and sclerosing have been reported.[21] The Nodular variety may masquerade as either fibroadenoma or carcinoma. We observed a nodular variety of lesions in our patients. SE revealed mosaic color patterns with elasticity scores of 2 each, benign size ratios (<1), and low SRs (<3.85) in these masses. The SE helped in the characterization of these indeterminate masses, which were confirmed to be tubercular mastitis on pathology.
Secretory carcinoma of the breast, in an 11-year-old girl, showed a color-coded elasticity score of 4, a size ratio of 1.18, and an SR of 6.24. These SE features favored the diagnosis of a malignant mass. Secretory carcinoma of the breast is also called juvenile carcinoma of the breast. The term “Juvenile” was used, owing to its higher incidence in adolescent females. However, this rare variety of breast carcinoma is also reported in adult females.
A few limitations of SE we encountered in our study were that it was a retrospective study, the technical limitation wherein large-sized masses could not be entirely depicted in the space provided for elastography on the US screen, leading to inappropriate assessment of size ratios. Additionally, the dense calcifications within a lesion would have led to falsely increased SRs. The critics of SE believe it is limited in being an operator-dependent and semi-quantitative technique as opposed to SWE, which helps in better quantitative assessment of the stiffness by measuring shear wave velocities. However, Strain elastography, even though it is a semi-quantitative technique, still carries importance in breast imaging, due to the assessment of SR, which measures the amount of strain produced in the breast tissue under examination, after the application of a desired amount of stress, and as previously stated, in developing countries, SE being more economical is widely available, vis a vis shear wave elastography.
CONCLUSION
It is concluded from our study that SE plays an important role in the differentiation and characterization of indeterminate breast masses. This study also reveals that SE possesses a better diagnostic accuracy, with a lower false positive rate than the Conventional US, in the differential diagnosis of breast masses, which definitely helps in bringing down the number of unnecessary breast biopsies. In addition, our study also documents SE features of secretory carcinoma, rapidly growing fibroadenomas, chronic galactocele, and tubercular mastitis.
Ethical approval:
The research/study was approved by the Institutional Review Board at VMMC and Safdarjung Hospital, number IEC/VMMC/SJH/CERT/2026-April/60, dated 9th April 2026.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript, and no images were manipulated using AI.
Financial support and sponsorship: Nil.
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