Ultrasound strain and attenuation imaging for detection of uterine masses

Abnormal uterine bleeding (AUB) is one of the most common symptoms patients present in the gynecology unit in both post-menopausal and pre-menopausal women. Some of the major causes of dysfunctional uterine bleeding are benign tumors or ingrowths such as; leiomyomas (fibroids), endometrial polyps, and adenomyosis. Other causes are malignant such as endometrial cancer or uterine cancer. It is important to have an accurate diagnosis of the type of uterine masses that cause AUB since clinical treatment and management differ substantially. Ultrasound elastography and attenuation imaging are envisioned as an optional modality to augment standard B-mode imaging. Palpation has been used for centuries to determine stiffness variation in tissue.;Ultrasound strain imaging potentially can be useful in the detection of such masses. We show the feasibility of a novel approach to strain imaging of the uterus by combining an often used ultrasound examination (Saline Infused Sonohysterography) with ultrasound strain imaging. The elastic contrast has to be established between normal uterine tissue and stiffer masses such as leiomyomas (uterine fibroids) and between softer pathologies such as uterine cancer and adenomyosis. Strain images were estimated using a two-dimensional multilevel hybrid algorithm developed for ultrasound sector array transducers. Coarse displacements were initially estimated using envelope echo signals. This was followed by a guided, finer displacement estimation using window lengths on the order of 6 wavelengths and 7 A-lines on radiofrequency data.;Strain images were obtained by estimating displacement slopes using least squares estimation. The quantification of viscoelastic characteristics of tissue and associated pathologies globally and locally are presented. Attenuation estimation has been previously used to quantify the underlying tissue pathology using ultrasound pulse-echo imaging for eventual use in clinical diagnosis. For an accurate estimate of the attenuation slope, the impact of sound speed variations and backscatter intensity variations for different estimation approaches need to be evaluated. The accuracy of three frequency domain estimation methods, namely the reference phantom method, the centroid downshift method and a hybrid method are presented. In-vivo attenuation images of the uterus from data acquired during SIS procedures are also shown.