Overview of the uses of Sonoelastography in

Gynecology

What is Sonoelastography?

Sonoelastography is an imaging modality that maps the elastic properties of soft tissue.

The elastic properties of a certain tissue is an important characteristic that can change with many pathophysiological processes as ageing , acute and chronic inflammation or in malignant changes.

Tissue Distortion The main Principle behind Sonoelastography is creating

a distortion in a certain ROI and comparing the elasticity of its different parts.

To image the mechanical properties of tissue, we need to see how it behaves when deformed. There are three main ways:

1-Pushing or vibrating the surface of the body with a mechanical device or the practitioner's arm

2-Using ultrasound to create a 'push' or a high or low frequency mechanical wave inside the tissue

3-Observing distortions created by normal physiological processes, like the pulse or heartbeat

An external compression is applied to tissue, and the ultrasound images before and after the compression are compared. The areas of the image that are least deformed are the ones that are the stiffest, while the most deformed areas are the least stiff and are given a different color mapping by the machine

Sonoelastography in Cervical cancer

Accurately Delineating the extent and site of the lesion and malignancy likehood by Strain Ratio .

The Strain Ratio is one way of semi-quantifying the stiffness of a tissue

A SR-measurement compares the strain in two manually selected regions of interest (ROIs) on the elastograms. One ROI is placed in the focal lesion, and the reference ROI is placed in the surrounding normal tissue, preferably in the same depth as the lesion.

The SR is automatically calculated by the elastography software and yields the fraction of the average strain in the reference area divided by the average strain in the lesion. The higher the SR, the higher the likelihood of malignancy.

When the strain ratio of a cervical lesion was higher than 4.53, it is confidential to be diagnosed as malignant

The strain Ratio of this cervical lesion was 2.17 after excision it was confirmed to be a cervical leiomyoma

The Strain Ratio of this lesion was 5.17 after excision it was confirmed to be an invasive cervical squamous cell carcinoma

Role of Sonoelastography in Uterine Fibroids

Real‐time Sonoelastography images of the two fibroids. The strain ratio is evaluated by comparing the mean strain in a region of interest centered on the myoma, with the mean strain in a region of interest in the surrounding myometrium close to the probe. The ratio shows a mean strain about 10 times greater for normal myometrium compared with the fibroids.

Conventional B‐mode imaging with power Doppler demonstrating two uterine fibroids. Peripheral vascularization of the fibroids is evident.

Color mapping of uterine strain allows precise determination of the so‐called ‘security wall’ between the fibroids and the endometrium or uterine serosa before surgical resection with laparoscopy or hysteroscopy.

Fibroids V.S Adenomyosis

Differentiation between Fibroids and Adenomyoma can be challenging by B-Mode U/S .

Sonoelastography exhibits a typical color Map in Adenomyoma of a soft (Green) lesion with a central core that is even less Stiff (Red) , where as Fibroids are depleted uniformly in the color blue as they are stiff.

Adenomyosis

Fibroid

Endometrial Pathologies

Color Coded images and Elasticity indices (which have lower scores in stiffer tissues) have shown that normal and atrophic endometrium have significantly lower scores than endometrial hyperplasia, cancer and polyps.

Other Potential uses in Obstetrics .

Sonoelastography of the uterine cervix prior to induction of labor as a predictor of cervical dilation time compared to Bishop score and cervical length measurement (Hee L et al , 2014).

Elastography in predicting preterm delivery in asymptomatic, low-risk women (Slawomir Wozniak et al. , 2014)

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