Safety and Feasibility of ActivSight(tm) in the Identification of The Ureter Via Riboflavin Fluorescence

In the 2019 publication, "A zwitterionic near-infrared fluorophore for real-time ureter identification during laparoscopic abdominopelvic surgery," by de Valk, et al. [1], the authors present the clinical need for real-time identification of the ureter during laparoscopic abdominal surgery: "Iatrogenic ureteral injury is amongst the most feared complications of lower abdominal surgery, with incidence varying from 0.5 - 1% in cancer surgery, to as high as 10% in gynecologic oncologic surgery [2-5]. Ureters are thin-walled and at risk for injury as they are poorly distinguished from surrounding retroperitoneal tissue and are usually in a collapsed state. Unrecognized ureteral damage during surgery can lead to long-term morbidity, including kidney failure." In their publication, this team proposes the use of a zwitterionic near-infrared fluorophore that could be detected in real-time via near-infrared fluorescence imaging. Activ Surgical has developed and commercialized ActivSight™, a near-infrared fluorescence detector, that combines an innovative form factor and proprietary software to deliver precise, objective, cost efficient real-time visualization of blood flow and tissue perfusion intraoperatively for laparoscope-based surgery. A small adaptor fits between any existing laparoscope and camera system and a separate light source is placed along any current commercial system to deliver objective real-time tissue perfusion and blood flow information intraoperatively. ActivSight™ received 510(k) clearance from the US FDA in 2020. According to its labelling, ActivSight™ is intended to provide real-time endoscopic fluorescence and near infrared imaging. ActivSight™ enables surgeons to visually assess blood flow and related tissue perfusion using fluorescence and near infrared imaging, and at least one of the major bile ducts (cystic duct, common bile duct or common hepatic duct) using fluorescence, all during minimally invasive surgery. In this clinical feasibility study, Activ Surgical proposes a slightly different approach from the above-referenced publication to achieve real-time ureter identification during elective laparoscopic abdominal surgery. Instead of utilizing a zwitterionic fluorophore to fluoresce the ureter, Activ Surgical is investigating a common over-the-counter water-soluble vitamin: riboflavin, also known as vitamin B2.

While typically administered as a dietary supplement, the medical literature contains many large studies of riboflavin use as prophylaxis for migraines [6]. It has also been studied and used to identify ureteral jets during cystoscopy as a method of confirming ureter patency after pelvic prolapse surgery [7-8].

Riboflavin possesses properties of fluorescence, with three strong areas of fluorescence [9] in the visible wavelength spectrum. To detect the fluorescence of riboflavin, changes were made to ActivSight™ hardware for this study; these changes are detailed herein. The main Objective of this study is to determine the safety and feasibility of a prototype ActivSightTM in identifying the ureter in real-time during elective laparoscopic abdominopelvic surgery after pre-surgical administration of riboflavin. This study seeks to identify the ureter only; ActivSight™ will not be used to guide treatment or the surgical procedure. As such, this is a non-significant risk study. Riboflavin is a common dietary supplement and will be administered at dosages shown previously to be well-tolerated for migraine prophylaxis [6]. ActivSight™ is an imaging system connected to the standard laparoscopic system already existing in the OR at the site. Changes made to the commercial ActivSight™ hardware for this study introduce no significant risk. Subjects presenting for elective laparoscopic abdominopelvic surgery (meeting the inclusion/exclusion criteria detailed below) will be consented and asked to permit the surgeons to identify their ureter with the prototype ActivSight™ system during elective laparoscopic surgery after ingesting the proper dosage of riboflavin pre-surgery. Video of the ureter examination will be recorded and analyzed post-surgery; retained video will be devoid of any protected health information.