Evaluation of Uterine Fibroids by Contrast Enhanced Ultrasound (CEUS) and Subharmonic-Aided Pressure Estimation (SHAPE) Pre and Post Uterine Artery Embolization (UAE)

Uterine fibroids affect approximately 30% of all women in the United States or about 45 million individuals. The clinical diagnosis of uterine fibroids is two to three times more common in African- American women than in Caucasian women. Uterine artery embolization (UAE) is a nonsurgical therapy that shrinks fibroids by blocking arterial blood flow to the lesions. Prior to the UAE

procedure almost all patients receive a contrast-enhanced MRI, which is currently considered the reference imaging method. After the UAE, the current strategy is to request a contrast-enhanced MRI to evaluate the efficacy of the treatment. However, an MRI is not always available and remains very expensive. Ultrasound imaging offers a low cost, non-invasive, and readily available

approach, which can characterize both structural and functional features of tumor vascularity from its earliest stages. Moreover, microbubble-based ultrasound contrast agents (UCA) not only enhance the backscattered signals, but at higher acoustic pressures they also act as nonlinear oscillators producing significant energy components in the received echo signals. These nonlinear

bubble echoes can be separated from tissue echoes and used to create contrast specific ultrasound imaging modalities (e.g., harmonic imaging; HI). HI preferentially enhances and displays contrast signals rather than surrounding tissue echoes by transmitting at the fundamental transducer frequency (f0) and receiving at the second harmonic (2f0). HI is commercially available

on most state-of-the-art ultrasound scanners. Our group developed the fundamental concept of contrast-enhanced subharmonic-aided pressure estimation (SHAPE). This approach relies on using the inverse linear relationship between subharmonic signals from UCA and the ambient pressures. Therefore, we believe that development of SHAPE as an accurate noninvasive

technique for measurement of ambient pressure can be translated for the evaluation of uterine fibroids pressures in order to establish parameters for dynamic evaluation. Thus, this study goals are to determine the patterns of uterine fibroid vascularity pre and post UAE using CEUS resulting in an alternative to gadolinium-enhanced MRI that is less expensive, has less contra-indications

and side effects, is real time, and noninvasive helping physicians to evaluate the result of UAE procedures. Also, this study will evaluate uterine fibroid pressures using SHAPE, comparing the results with normal myometrium tissue in order to determine its characteristics and tissue differences, which we believe will lead to the development of a new biomarker for the diagnosis

and treatment of uterine fibroids.