Multiparametric Cystoscopy for Detection of Bladder Cancer Using Real-time Multispectral Imaging

Abstract

Background: Various imaging modalities can be used in addition to white light (WL) to improve detection of bladder cancer (BC). Objective: To use real-time multispectral imaging (rMSI) during urethrocystoscopy to combine different imaging modalities to achieve multiparametric cystoscopy (MPC). Design, setting, and participants: The rMSI system consisted of a camera with a spectral filter, a multi-LED light source, a microcontroller, and a computer for display and data acquisition. MSI with this system was achieved via temporal multiplexing. Surgical procedure: MPC was performed in ten patients with a diagnosed bladder tumor. Measurements: We gathered evidence to prove the feasibility of our approach. In addition, experienced urologists performed post-interventional evaluation of images of individual lesions. Images were independently rated in a semiquantitative manner for each modality. A statistical model was built for pairwise comparisons across modalities. Results and limitations: Overall, 31 lesions were detected using the rMSI set-up. Histopathology revealed malignancy in 27 lesions. All lesions could be visualized simultaneously in five modalities: WL, enhanced vascular contrast (EVC), blue light fluorescence, protoporphyrin IX fluorescence, and autofluorescence. EVC and photodynamic diagnosis images were merged in real time into one MP image. Using the recorded images, two observers identified all malignant lesions via MPC, whereas the single modalities did not arouse substantial suspicion for some lesions. The MP images of malignant lesions were rated significantly more suspicious than the images from single imaging modalities. Conclusions: We demonstrated for the first time the application of rMSI in endourology and we established MPC for detection of BC. This approach allows existing imaging modalities to be combined, and it may significantly improve the detection of bladder cancer. Patient summary: Real-time multispectral imaging was successfully used to combine different imaging aids for more comprehensive illustration of bladder tumors for surgeons. In the future, this technique may allow better detection of bladder tumors and more complete endoscopic resection in cases of cancer.