Purpose: The aim of this pilot study was to assess the feasibility and value of wide-field autofluorescence imaging (AFI) for the detection of bladder cancer during transurethral resection of the bladder (TUR-B).
Methods: For imaging, the D-Light/AF System (Karl Storz GmbH, Tuttlingen, Germany) and a customized band pass filter (≈ 480-780 nm) at the eyepiece of the endoscope were used. The excitation light wavelength was 440 nm. Representative spectral measurements of tissue autofluorescence (AF) were performed using a spectrometer attached behind the AF band pass filter in selected patients. During TUR-B, cystoscopy was performed in white light (WL) followed by wide-field AFI. Lesions were classified as suspicious or normal using either modality.
Results: Representative spectral measurements using excitation at a wavelength of 440 nm resulted in significantly lower fluorescence intensity of malignant versus non-malignant tissue. Overall, 56 lesions (30 cancerous and 26 non-malignant) in 25 patients were assessed and classified by wide-field AFI. Papillary tumors as well as flat lesions lacked the green fluorescence seen in normal urothelium, thus emerging as "brown-reddish" areas. When compared with histopathological findings, the pooled per-lesion sensitivity and specificity for AF were 96.7 and 53.8%, respectively. For WL these values were 86.7 and 69.2%, respectively.
Conclusion: Wide-field AFI imaging during TUR-B is simple and easy to use. Our preliminary data suggest that AFI has the potential to increase the detection rates of bladder tumors compared with WL without the need of intravesical instillation prior to the procedure.
Keywords: Autofluorescence; Bladder cancer; Endoscopy; Imaging; TUR-B.