Quantitative assessment of urethral vascularity in nulliparous females using high-frequency endovaginal ultrasonography.

PURPOSE: To assess the vascular parameters in the urethra of nulliparous females and to compare the vascularity among various parts of the urethra, using high-frequency endovaginal ultrasonography (EVUS). METHODS: Twenty-two nulliparous women, mean age 27 years, underwent EVUS using a biplane transducer at 12 MHz frequency. Color Doppler examinations of the urethra were recorded and further evaluated off-line using special software (Pixel Flux) for quantitative assessment of the vascularity. The urethra was divided into four regions of interest (ROIs) in the midsagittal plane and three ROIs in the axial plane. The following parameters were measured: velocity (V), perfused area (A), perfusion intensity (I), pulsatility index (PI), and resistance index (RI). Interobserver and intraobserver reproducibility analysis was also performed. RESULTS: In midsagittal plane, the midurethra presented the highest value of V and lowest value of A. The intramural part showed the lowest value of I and the highest values of RI and PI. In the distal urethra, the highest value of I and the lowest value of RI was seen. In the axial plane, the values of V, A, and I were statistically significantly higher in the external part of the midurethra compared with the internal part. Excellent interobserver and intraobserver reproducibility was shown in the majority of parameters for the entire urethra. CONCLUSIONS: Vascularity differs in different parts of the urethra. Pixel Flux is a valuable tool for providing reproducible quantitative analysis of vascular parameters for the entire urethra.