DEVELOPMENT OF NONINVASIVE VELOCITY FLOW VIDEO URODYNAMICS USING DOPPLER SONOGRAPHY - PART I - EXPERIMENTAL URETHRA

Purpose: We believed that a totally noninvasive video urodynamic syste m could be invented based on the concept of Doppler ultrasonography. T o develop this system we measured flow velocity in an experimental ure thra using 4 materials, including natural urine. Materials and Methods : A cellulose tube was inserted into a standoff pad as an experimental urethra. Degassed water, distilled water, urine and liposome (multi-l amellar particles) solution comprised the 4 materials used to compare signal intensity and flow velocity at various flow rates. The flow rat e from the tube was measured with a uroflowmeter. The Doppler image an d digital uroflow signal data were processed by a computer. Results: D oppler signals and flow velocity curves could be sufficiently obtained using distilled water, urine and liposome solution, while degassed wa ter showed no Doppler signals at any flow rate. Minimum flow rate at w hich clear Doppler signals were continuously detected from the angle i n the frontal plane was greater than 3.0 ml. per second for distilled water, greater than 1.5 for urine and greater than 0.3 for liposome so lution. Maximum flow velocities were identical in these 3 materials at a flow rate of greater than 2.0 ml. per second. The functional cross- sectional area of the tube showed a constant value irrelevant to the i nitial flow rate. Conclusions: Flow velocity could be measured by Dopp ler ultrasound above a certain minimal flow rate. Dissolved gasses hav e an important role in creating Doppler signals. Flow velocity, veloci ty related parameters and functional cross-sectional area can diagnose and localize the area of bladder outlet obstruction. Liposome solutio n may be helpful in detecting velocity in low flow states in future sy stems.