Raman spectroscopic detection of changes in molecular composition of bladder muscle tissue caused by outlet obstruction

Bladder outlet obstruction leads to loss of bladder function as a result of structural damage. Functional parameters of an obstructed bladder do not enable a prediction of the clinical outcome of removal of the obstruction. Therefore, other diagnostic methods are needed. This study presents first results of an approach based on Raman spectroscopy, which aims to detect changes in molecular composition of the bladder wall that may have diagnostic value. Raman spectroscopic mapping of unfixed sections of damaged and undamaged bladder wall from a guinea pig model of bladder obstruction was used to detect changes in composition of bladder muscle tissue. Collagen infiltration in muscle fibers was clearly visualized. Other compositional changes that are revealed include the accumulation of glycogen in obstructed bladder wall as well as an apparent but as yet unknown change in protein composition. In vivo Raman spectroscopic application may enable determination of bladder structure without the need for biopsies. These initial findings show that Raman spectroscopy can be a valuable diagnostic tool for evaluation of the extent of bladder structure loss.