Diagnostic Value of Complementary Strain Elastography in the Classification of Breast Masses

Background: Breast cancer is the commonest cancer in women. Ultrasound has a high sensitivity but low specificity in the classification of benign and malignant breast masses. Strain elastography has the potential of increasing the specificity of breast ultrasound in classifying malignant and benign breast masses and reducing the number of benign breast biopsies performed. The diagnostic value of breast elastography in African women is not known. Objective: The aim of this study was to evaluate the additive diagnostic value of strain elastography to conventional ultrasound in the classification of malignant and benign breast masses in an African population. Materials and Methods: This prospective study was carried out between August and December 2016 in the Radiology Department, Aga Khan University Hospital, Nairobi. Conventional ultrasound and strain elastography were carried out in 74 breast masses. Histology was used as the refence standard. Mean elasticity scores were compared for malignant and benign masses using the two-sample t test. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for conventional ultrasound, elasticity score, length ratio and combined method were calculated. Receiver operating characteristic (ROC) curve analysis was also performed. Results: The mean elasticity score of malignant and benign masses was 4.29 (±0.750) and 2.05 (±0.916) respectively. The difference in the mean values was statistically significant (P\u3c0.0001). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 97.1%, 71.8%, 75.6% and 96.6% respectively, for conventional ultrasound and 97.1%, 92.3%, 91.9% and 97.3% respectively, for combined method. Combining elasticity score with conventional ultrasound resulted in a significant increase in the specificity (P value = 0.0012) and PPV (P value = 0.0074) compared to conventional ultrasound alone. The sensitivity and specificity of length ratio was 94.3% and 92.3% respectively compared to 94.3% and 89.7% respectively for elasticity score. Conclusion: Adding strain elastography to conventional ultrasound significantly improves the specificity and positive predictive value in classifying malignant and benign breast masses in the African population. There was no significant difference between elasticity score and the length ratio