Contrast-enhanced ultrasound imaging utilizing the nonlinear responses of microbubbles is proposed for identifying ventricular shunt malfunction. The developed method suppresses the signal from walls of a shunt catheter and background tissues, and allows accurate measurements of the cerebrospinal fluid flow within the shunt catheter using a relatively small concentration of microbubbles. The flow rates estimated in the linear mode were significantly underestimated (65% at 0.1ml/min and 5.0% microbubble concentration) while estimates using the nonlinear mode were not. Overall, the nonlinear responses of microbubbles improve the estimation of flow rates in a shunt catheter at low concentrations of microbubbles.
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© 2017 The Japan Society of Applied Physics.