Acoustic radiation force imaging (ARFI) in the non-distended bladder does not predict abnormal urodynamic parameters in children

Introduction: Acoustic radiation force imaging (ARFI) is a recently developed form of ultrasound imaging that allows in-vivo measurement of tissue stiffness. This technology could be useful at predicting bladder compliance in children. We hypothesize that tissue stiffness, as measured by ARFI, correlates with abnormal bladder compliance and capacity in patients with bladder dysfunction. Methods: Patients who presented for cystometrography (CMG) underwent ARFI of the bladder wall. Nine bladder wall shear wave speed (SWS) measurements were acquired using point and 2D ultrasound shear wave elastography. The mean for each ARFI technique was correlated to bladder compliance, calculated using Wahl’s dimensionless number. ARFI parameters also were correlated with bladder capacity. Results: A total of 25 patients were enrolled. Mean age at time of enrollment was 4.23.9 years (range: 2 months to 15 years). There was no significant correlation between bladder compliance and point shear wave speed measurements (r=-0.22, p=0.31) or 2D shear wave speed measurements (r =-0.35, p=0.1). A total of 19 patients had bladder capacity below EBC. There was no significant correlation between bladder capacity and point shear wave speed measurements (r =-0.08, p=0.7) or 2D shear wave speed measurements (r=-0.36, p=0.09). Conclusions: Our results did not demonstrate a significant correlation between bladder wall ARFI shear wave measurements and bladder compliance or bladder capacity. Further studies are warranted to determine whether ARFI may be used to predict abnormal urodynamic parameters in children.