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 (P_det). Our purpose is to report on technical developments toward a noninvasive and accurate estimation ofP_detthrough ultrasound (US), a technique we refer to as US-UDS.Approach.The proposed US-UDS technique produces an estimate ofP_detby 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 forP_detestimation. US-UDS analysis for estimation ofP_detwas 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 ofP_detwhile response operator characteristic analysis was used to evaluate US-UDS for detection of detrusor activity (parameterized as UDSP_det>15 cmH₂O).Main results.US-UDS was able estimateP_detwithin 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 UDSP_detmeasurements 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 ofP_detas 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 ofP_detare feasible from US measurements.