The evolution of near infrared spectroscopy in urology
In the 50 year history of NIRS, biomedical applications in urology are recent. This review summarizes technical advances and novel enquiry that have led to hemodynamic monitoring of the testis, measures of renal function, evaluation of the pelvic floor in women, and interrogation of the bladder. An overview is given of how bladder spectroscopy has evolved and the evidence that non-invasive transcutaneous optical monitoring of the anterior bladder wall now enables variations in the organ's hemodynamics and oxygen supply and demand to be identified in real time. Research indicates that bladder blood flow and oxygenation differ in health and disease, and because NIRS monitors changes in the microcirculation bladder spectroscopy adds physiologic information not available by other means, including via the current invasive method for evaluation of voiding dysfunction.
Confidence that bladder NIRS yields physiologic data comes from the patterns of chromophore change and tissue oxygen saturation observed corresponding to variations in these parameters in NIRS studies of other tissues in response to known physiologic events. Importantly, when interpreted based on this prior research, novel insight is gained about probable causal pathologies underlying bladder dysfunction. Studies to date warrant further research, continued refinement of instrumentation, extension of the scope of monitoring, and exploration of diagnostic software algorithms.