NGHIÊN CỨU SO SÁNH SIÊU ÂM ĐÀN HỒI STRAIN ELASTOGRAPHY (SE) SO VỚI SHEARWAVE ELASTOGRAPHY (SWE) TRONG BỆNH LÝ U VÚ NỮ TẠI MEDIC TPHCM 2019

Abstract

Objective: Combining B-mode US, BI-RADS classification and applying 2 types of elastography: Strain Elastography (SE) and Shear Wave Elastography (SWE) on RS85 ultrasound scanner (Samsung) in diagnosis of benign/ malignant breast tumors. Detecting diagnostic value for each method and when combining them.
Materials and methods: Selecting female breast tumors that classified Birads 3,4,5 by B-mode US, examining elastography at the same time by 2 methods: SE and SWE using L2-9MHz probe on RS85 ultrasound scanner (Samsung) from August to October, 2019 at Medic Medical Center in HCMC. Collecting data of 2 types of Elastography:
- SE: collecting 3 values: (1) color mapped elastogram according to Tsukuba elasticity score, (2) E/B ratio (the largest transversal diameter that hardest color - coded on the color map / the largest transversal diameter of tumor on B-mode US) (<1 or >1), (3) ratio B/A (A= tumor lesion, B= normal fat tissue above the lesion).
- SWE: measuring the tissue stiffness (kPa) and shear wave velocity (m/s) (according to color-coded tumor stiffness map, selecting the hardest point that satisfied RMI (reability measurment index) ≥ 0.4. Measuring each method 3 times on the same tumor. Bi-rads 3-4-5 lesions undergone biopsy (FNAC and/ or core biopsy) to have determined diagnosis. Then calculating the diagnostic value of each method and when combining the 2 methods. Using the SPSS 20 software for statistics and analyzing.
Results: The study has 84 breast tumors (51 benign and 33 malignant) that have determined diagnosis by cytology and histology.

1. Strain Elastography value:
1.1. Choosing color map according to Tsukuba elasticity score from 1→5 in diagnosis has sensitivity (90%), specificity (88.2%), positive predictive value (83%), negative predictive value (93.8%), accuracy (8.3%)
1.2. Choosing the E/B ratio (the largest transversal diameter that hardest color - coded on the color map / the largest transversal diameter of tumor on B-mode US) value (that <1 suspected benign tumor and ≥ 1 suspected malignancy) has sensitivity (87%), specificity (90.2%), positive predictive value (85.3%), negative predictive value (92%), accuracy (89.3%)

1.3. The ratio of mean strain elastography value of malignant and benign breast tumor / fat tissue are (8.1+/- 3.7) and (2.4+/-1.3) (p<0,001).The ratio at cut-off value (3.2) has the highest sensitivity (97%) and specificity (84.3%) in diagnosing malignant breast tumors. Area under the ROC curve calculated (0.969). Positive predictive value (80%). Accuracy (89.3%).
2. Shear wave elastography (SWE) value:
2.1. Shear wave mean velocity of benign and malignant tumor groups are (3.9 ± 1.1) and (5.9 ± 1.3) (m/s) (p<0,001). Mean ratio at the cut-off value (4.2m/s) has the highest sensitivity (90.9%) and specificity (66.7%) in diagnosing malignant breast tumors. Area under the ROC curve calculated (0.873).Positive predictive value (63.8%). Negative predictive value (91.8%). Accuracy (76.2%).
2.2. Mean stiffness value of benign and malignant breast tumor groups are (49.7 ± 28.2) and (108±4.5) (kPa) (p<0,001). Mean ratio at the cut-off value (50.3 kPa) has sensitivity (90.9%), specificity (66.7%). Area under the ROC curve calculated (0.864), positive predictive value (61.2%), negative predictive value (91.4%), accuracy (73.8%)
3. Combination of SE and SWE value Combining the 2 types of elastography SE and SWE in diagnosing breast tumor by evaluating E/B of SE and shear wave velocity (m/s) of SWE increases the strongly sensitivity (100%), specificity (52,9%) and positive predictive value (57,9%), negative predictive value (100%), accuracy (71,4%), helps to reduce unnecessary biopsied cases.
Conclusions: SE and SWE are useful in diagnosing breast tumor. Combining the 2 types of elastography SE and SWE have strongly sensitivity, helps to reduce unnecessary biopsied cases