Ultrasound urodynamic studies (US-UDS): noninvasive estimation of detrusor pressure through ultrasound.

Objective.Urodynamic studies (UDSs) are vital for evaluating bladder function but require invasive catheterization to measure detrusor pressure (Pdet). Our purpose is to report on technical developments toward a noninvasive and accurate estimation ofPdetthrough ultrasound (US), a technique we refer to as US-UDS.Approach.The proposed US-UDS technique produces an estimate ofPdetby using US to induce and track elastic waves that propagate within and around the bladder wall. Key components of the US-UDS processing include: an US sequence with dense time sampling; an empirical correction accounting for deviation from a Lamb wave dispersion model; and constrained optimization forPdetestimation. US-UDS analysis for estimation ofPdetwas applied to 533 distinct data points collected from 3 human subjects undergoing concurrent UDS. Concordance analysis was used to evaluate agreement between US-UDS and UDS measures ofPdetwhile response operator characteristic analysis was used to evaluate US-UDS for detection of detrusor activity (parameterized as UDSPdet>15 cmH2O).Main results.US-UDS was able estimatePdetwithin 10 cmH2O and 5 cmH2O of UDS measurements with coverage probabilities of 95.7% and 68.8% respectively. Furthermore, US-UDS was able to detect UDSPdetmeasurements greater than 15 cmH2O with a sensitivities and specificities of 0.99 and 0.83 using a fixed threshold (>15 cmH2O for US-UDS) and 1.0 and 0.93 for an optimized threshold (> 11.08 cmH2O for US-UDS).Significance.Our results show that the technical developments of US-UDS put forth in this work are able produce accurate and useful estimates ofPdetas compared to traditional UDS. Although additional research with a large number of subjects is needed to fully characterize the clinical utility of US-UDS, the developments and results from this work demonstrate that clinically useful non-invasive measurements ofPdetare feasible from US measurements.