Are Results of 4-D Ultrasound Angiography Examinations Dependent on the Doppler Technology Applied? Comparison of Results Obtained from an In Vivo Model

We aimed to evaluate the agreement of results obtained by 4-D spatio-temporal image correlation (STIC) angiography with two options of Doppler technology (power Doppler [PD] and high-definition flow [HDF]) from an ovary as an in vivo model. Thirty-eight ovaries were recorded by trans-vaginal ultrasound examination in the first part of the menstrual cycle. Two STIC sequences (4-D HDF and 4-D PD) were stored. Volumetric pulsatility index, volumetric resistance index and volumetric systolic/diastolic index for each of these sequences were calculated, and their mean values were compared and correlated. Agreement between 4-D HDF and 4-D PD was assessed using the intra-class correlation coefficient. Intra-class correlation coefficients for all three indices were high, but 95% confidence intervals and limits of agreement were wide. We conclude that both 4-D power Doppler and 4-D high-definition flow may be used for calculating volumetric pulsatility index, volumetric resistance index and volumetric systolic/diastolic index from a STIC sequence, at least in ovaries used as an in vivo model. However, values obtained by both methods cannot be used interchangeably.