Optical Coherence Tomography for Prostate Cancer and Beyond

Abstract

Since it was first used to evaluate human genitourinary tissue in 1997, OCT has emerged as a promising modality to provide real-time, high-resolution imaging of urologic organs. In the bladder, it has demonstrated a high sensitivity in identifying regions of the bladder suspicious for CIS and between invasive and noninvasive malignancy; it has been studied as an “optical biopsy” both during the initial cystoscopic diagnosis and intraoperatively in bladder-preserving surgery. Several small, ex vivo studies have shown promising results in the ability of OCT to demonstrate histopathologic alterations to renal morphology such as in renal ischemia and malignancy. It may also in the future improve sperm retrieval rates by better identifying tubules with isolated foci of spermatogenesis in these men with nonobstructive azoospermia. Finally, multiple studies have begun to demonstrate OCT’s ability to differentiate between the periprostatic anatomy and aid in the visualization of the neurovascular bundle and surgical margins. Despite the promising results of these initial studies, several limitations remain. In almost all studies, depth of penetration was recognized as a common limiting factor. At a maximum of 2 mm depth, OCT cannot provide imaging of deep tissue. In bladder cancer, for example, OCT cannot always provide sufficient imaging to judge the invasion depth of a tumor if the diameter of the tumor is already greater than 2 mm. In addition, most OCT studies have taken place in ex vivo. Larger clinical, in vivo trials are required to determine its ability to provide information to guide clinical decisions and if its use positively affects outcomes. Theoretically, future improvements of OCT delivery could allow for such technology to be placed at the end of robotic and laparoscopic instruments, thus providing “smart instruments” that could provide immediate and real-time assessment of tissue structure and architecture.