Transvaginal 3D Image-Guided High Intensity Focused Ultrasound Array

Abstract

The goal of this project is to develop a transvaginal image‐guided High Intensity Focused Ultrasound (HIFU) device using piezocomposite HIFU array technology, and commercially‐available ultrasound imaging. Potential applications include treatment of uterine fibroids and abnormal uterine bleeding. The HIFU transducer was an annular phased array, with a focal length range of 30–60 mm, an elliptically‐shaped aperture of 35×60 mm, and an operating frequency of 3 MHz. A pillow‐shaped bag with water circulation will be used for coupling the HIFU energy into the tissue. An intra‐cavity imaging probe (C9‐5, Philips) was integrated with the HIFU array such that the focal axis of the HIFU transducer was within the image plane. The entire device will be covered by a gel‐filled condom when inserted in the vaginal cavity. To control it, software packages were developed in the LabView programming environment. An imaging algorithm processed the ultrasound image to remove noise patterns due to the HIFU signal. The device will be equipped with a three‐dimensional tracking system, using a six‐degrees‐of‐freedom articulating arm. Necrotic lesions were produced in a tissue‐mimicking phantom and a turkey breast sample for all focal lengths. Various HIFU doses allow various necrotic lesion shapes, including thin ellipsoidal, spherical, wide cylindrical, and teardrop‐shaped. Software control of the device allows multiple foci to be activated sequentially for desired lesion patterns. Ultrasound imaging synchronization can be achieved using hardware signals obtained from the imaging system, or software signals determined empirically for various imaging probes. The image‐guided HIFU device will provide a valuable tool in visualization of uterine fibroid tumors for the purposes of planning and subsequent HIFU treatment of the tumor, all in a 3D environment. The control system allows for various lesions of different shapes to be optimally positioned in the tumor to cover the entire tumor volume. Real‐time ultrasound imaging for guidance and monitoring of HIFU treatment provides an effective method for outpatient‐based procedures.