Emerging Endoscopic Imaging Technologies for Bladder Cancer Detection

Abstract

Modern urologic endoscopy is the result of continuous innovations since early 19th century. White light cystoscopy is the primary strategy for identification, resection, and local staging of bladder cancer. While highly effective, white light cystoscopy has several well-recognized shortcomings. Recent advances in optical imaging technologies and device miniaturization hold the potential to improve bladder cancer diagnosis and resection. Photodynamic diagnosis and narrow band imaging are the first to enter the clinical arena. Confocal laser endomicroscopy, optical coherence tomography, Raman spectroscopy, UV autofluorescence, and others have shown promising clinical and pre-clinical feasibility. We review their mechanisms of action, highlight their respective advantages, and propose future directions.

In vivo fluorescence navigation of gastric and upper gastrointestinal tumors by 5-aminolevulinic acid mediated photodynamic diagnosis with a laser-equipped video image endoscope

“…Nakamura et al [12] reported that the red color fluorescence intensity for experimental PDD was lower in Photofrin than ALA. Indeed ALA-mediated PDD remains concerning about false-positivity in prior studies [4] but we have noticed that the tumor margins could be clearly depicted red fluorescent signals, and be demarcated from the no tumorous surround tissue. Nevertheless, photobleaching [4,10] as seen in the present case should be reminded in redundant observation with ALA-mediated PDD.…”

“…On the other hand, the present study documented the evaluation of an all-in-one type endoscope integrated with the laser light source inside, which enabled the immediate blue light excitation at all times during ongoing endoscopy. Diverse endoscopic diagnostic modalities including imageenhanced endoscope using narrow band imaging or blue laser imaging and auto-fluorescence imaging endoscope has been developed [4,16]. As for the diagnostic accuracy of ALA-mediated PDD, the sensitive ability to identify tumors that are not detected by any other modalities or its specificity including false positivity for non-adenomatous lesions is beyond the scope of this study.…”

“…Exogenously administrated ALA increases cellular PpIX levels, and the overproduced PpIX causes evident emission of a red fluorescence at around 635 nm in certain tumors than the non-tumor surrounding tissues with a blue-violet light excitation [1][2][3]. Thus, ALA-mediated PDD relies on the tumor-specific accumulation of PpIX, and has become efficient in the detection of bladder and brain tumors [2,4].…”

“…Although it is known that adenocarcinomas tend to overproduce PpIX [4][5][6], there has been limited information on PDD for gastrointestinal (GI) cancers. Using specialized laparoscope, several studies showed the diagnostic usefulness of ALA-mediated PDD for peritoneal cancer dissemination [3,[7][8][9] or the liver metastasis [1].…”

“…Namikawa et al [10] reported on ALA-mediated PDD for gastric cancer specimens ex vivo using the rigid endoscope system. Indeed this method has shown outstanding sensitivity even for superficial bladder cancer identification [4,11] but it also involves the rigidity of cytoscope [4]. More recently, Nakamura et al reported the usefulness of upper GI endoscope that was capable of PDD using photosensitizers including ALA for gastric cancer.…”