Fluorescence cystoscopy enhances detection of early bladder cancer. Water used to inflate thebladder during the procedure rapidly contains urine, which may contain fluorochromes. This frequently degradesfluorescence images. Samples of bladder washout fluid (BWF) or urine were collected (15 subjects). We studiedtheir fluorescence properties and assessed changes induced by pH (4 to 9) and temperature (15°C to 41°C).A typical fluorescence spectrum of BWF features a main peak (excitation/emission: 320∕420 nm, FWHM =50∕100 nm) and a weaker (5% to 20% of main peak intensity), secondary peak (excitation/emission: 455∕525 nm, FWHM = 80∕50 nm). Interpatient fluctuations of fluorescence intensity are observed. Fluorescence intensity decreases when temperature increases (max 30%) or pH values vary (max 25%). Neither approach is compatible with clinical settings. Fluorescence lifetime measurements suggest that 4-pyridoxic acid/riboflavin is the most likely molecule responsible for urine’s main/secondary fluorescence peak. Our measurements give an insight into the spectroscopy of the detrimental background fluorescence. This should be included in the optical design of fluorescence cystoscopes. We estimate that restricting the excitation range from 370–430 nm to 395–415 nm would reduce the BWF background by a factor 2.

Fluorescence cystoscopy (FC) efficiently enhances the detection and improves the therapeutic management of early bladder cancer. During an FC, about 150 ml of water is needed to inflate the bladder. The water is quickly diluted by urine which can be fluorescent. If this bladder washout fluid (BWF) becomes fluorescent, the FC images are frequently degraded. Unfortunately, it is unclear which elements of the diet may contribute to this background fluorescence. We propose to start this exploration with over-the-counter (OTC) vitamin supplements. To this end, we measured excitation–emission matrices of urine samples and the kinetics of modifications of urine fluorescence obtained from nine healthy volunteers before, during, and after intake of a commercially available OTC vitamin supplement. The pharmacokinetics shows that the BWF fluorescence values reach a maximum 8 to 10 h after vitamin intake. They decrease in the half-day that follows and reach values close to baseline ~1 day afterward. Based on these results, we conclude that, in order to avoid degradations of fluorescence images, it is likely best that the intake of OTC vitamin supplements be avoided during the week preceding an FC.

Photodynamic therapy based on photoactivable porphyrins (PAPs) can treat various dermatological conditions. The side-effects as well as the non-selective or insufficient accumulation of PAPs in the targeted tissues limit performances. We studied the stability in solution at different temperatures (21 °C; 4 °C), different pH values (7.5; 2.0), and as a function of time of 5-aminolevulinic acid's Tyrosine-ester, a molecule presenting interesting properties to selectively produce PAPs in blood vessels after topical application. Solutions of this precursor can be kept up to 24 h at refrigerated temperatures and under acidic pH. At room temperature or physiological pH, they must be prepared minutes before their use.