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Access Type
WSU Access
Date of Award
January 2022
Degree Type
Dissertation
Degree Name
Ph.D.
Department
Biomedical Engineering
First Advisor
Mohammad Mehrmohammadi
Abstract
Gynecological cancer is the fourth most common cancer among women in the worldwide. As is the case for most kinds of cancers, early detection can increase the chances of treatment success. One of the significant challenges in diagnosing patients with cervical cancer involves detecting tumor extension within the cervical canal. Currently, conization or cone biopsy is a clinical procedure that involves the surgical resection of the cone-shaped volume of the high-grade dysplastic or cancerous cervical tissue size of the resected tissue. However, there are risks associated with this procedure, including primary or secondary hemorrhage, cervical stenosis, and subsequent infertility or an abnormal pregnancy. Thus, there is currently an unmet clinical need for developing an imaging system capable of providing accurate structural, functional, and molecular data for the early-stage detection of clinical biomarkers in cervical cancers. This Ph.D. dissertation introduces a miniaturized phased-array ultrasound (US) and photoacoustic (PA) theranostic system capable of providing multi-modal diagnostic information of gynecologic diseases such as cervical cancer. Additionally, it is capable of simultaneous tissue ablation. The developed PA/US endoscope consists of two parts: (1). an integrated endoscopic system that consists of a phased-array ultrasound endoscope, a compact light delivery system, and a sheath for imaging through the cervical canal, and (2) an external illumination system for delivering light to cervix tissue through the ectocervix. The integrated internal US/PA system consists of a 64-element phased-array US probe for providing a high-resolution 90-degrees sector imaging and seven silica core optical fibers (550 µm core diameter) for our internal light delivery system. The US probe is surrounded by these fibers, which project the laser light and ablation beam toward the tissue in front of the active aperture and yield aligned and overlapped US waves and light beams. In addition, a custom-built housing is designed to integrate light delivery and US imaging into a portable and compact system for cross-patient imaging. The total size of the internal theranostic system measures 6.89 mm, which allows it to access the cervical tissue in close proximity when positioned through the cervical canal. The external illumination is comprised of seven optical fibers polished and encapsulated inside a borosilicate capillary tube. Several simulations and ex vivo phantom studies have been conducted to characterize and evaluate the performance of the endoscope. Preliminary ex vivo phantom and tissue studies have shown high resolution and high contrast PA images. Additional ex-vivo studies have verified the tissue distinguishing capability of the theranostic endoscope by analyzing the measurable differences in the PA signal between pre-and post-ablated tissue. The results of an increase in the PA signal with temperature variations confirmed the ability of the proposed endoscope to provide real-time temperature feedback.
Recommended Citation
Basij, Maryam, "Design And Development Of A Miniaturized Combined Ultrasound /photoacoustic Endoscopic System" (2022). Wayne State University Dissertations. 3618.
https://digitalcommons.wayne.edu/oa_dissertations/3618