Detrusor overactivity assessment using ultrasound bladder vibrometry

Objective. Detrusor overactivity (DO) is a urodynamic observation characterized by fluctuations in detrusor pressure (P-det) of the bladder. Although detecting DO is important for the management of bladder symptoms, the invasive nature of urodynamic studies (UDS) makes it a source of discomfort and morbidity for patients. Ultrasound bladder vibrometry (UBV) could provide a direct and noninvasive means of detecting DO, due to its sensitivity to changes in elasticity and load in the bladder wall. In this study, we investigated the feasibility and applying UBV toward detecting DO. Approach. UBV and urodynamic study (UDS) measurements were collected in 76 neurogenic bladder patients (23 with DO). Timestamped group velocity squared (c(g)(2)) data series were collected from UBV measurements. Concurrent P-det data series were identically analyzed for comparison and validation. A processing approach is developed to separate transient fluctuations in the data series from the larger trend of the data and a DO index is proposed for characterizing the transient peaks observed in the data. Main Results. Applying the DO index as a classifier for DO produced sensitivities and specificities of 0.70 and 0.75 for c(g)(2) P-det data series respectively. Significance. It was found that DO can be feasibly detected from data series of timestamped UBV measurements. Collectively, these initial results are promising, and further refinement to the UBV measurement process is likely to improve and clarify its capabilities for noninvasive detection of DO.