How elastography refines the BI-RADS category
During ultrasound of the mammary glands, each detected formation is assigned a BI-RADS category - from 1 (normal) to 5 (high probability of malignancy). The greatest difficulties are caused by category 3 and borderline 4a: according to some signs the formation looks benign, but according to others it does not. This is where elastography provides an additional argument.
Fibroadenomas and cysts retain the softness of the surrounding tissue and appear green and blue on the color map. A malignant tumor grows with a pronounced desmoplastic reaction - the connective tissue around it becomes denser, and on the map the zone is colored red, and the quantitative values are many times higher than those of a normal gland. Additionally, the stiffness coefficient is assessed - the ratio of the indicators of the node and adjacent healthy tissue.
The study has no age restrictions and is safe during pregnancy and lactation. The optimal time for menstruating women is the first phase of the cycle, from the 5th to the 12th day, when the gland is less swollen.
What does elastography show?
Elastography measures the stiffness (elasticity) of tissue - a parameter that a doctor could previously assess only with his hands during palpation. Healthy tissue is soft and easily deformed, while scar, fibrous and tumor tissue is dense and rigid. The method translates this feeling into objective numbers that can be compared between studies.
The main practical value is in the differential diagnosis of focal formations. Benign nodes usually retain the elasticity of the surrounding tissue, while malignant ones are noticeably stiffer. This helps decide which nodes need to be monitored and which ones require a biopsy.
Compression and shear wave techniques
Compression elastography is based on light pressure with a sensor: the device compares tissue deformation and builds a color map. The method is qualitative - it shows what is harder and what is softer, but does not give absolute values.
Shear wave elastography (shear wave, which also includes liver fibroscan) uses the acoustic pulse of the device itself and measures the speed of propagation of the shear wave. The result is quantitative - in kilopascals, which allows you to track the dynamics during treatment.
Limitations of the method
The result is influenced by severe obesity, edema and active inflammation in the area of interest, as well as the depth of the formation: the deeper it is, the less reliable the measurements. Large calcifications and cysts produce artifacts.
Elastography is not an independent diagnosis, but one of the parameters. The final conclusion about the nature of the formation is given by a morphological study, that is, a biopsy.