Spatiotemporal image correlation using high-definition flow: a new method for assessing ovarian vascularization

The purpose of this study was to describe a new method for assessing ovarian vascularization using spatiotemporal image correlation (STIC)-high-definition flow (HDF).

Thirty healthy premenopausal fertile women were assessed in the follicular part of the menstrual cycle by transvaginal sonography. A 4-dimensional STIC-HDF volume was obtained from the nondominant ovary to assess 3-dimensional (3D) vascular indices (vascularization index [VI] and flow index [FI]) during one cardiac cycle in each women. Using 1-cm(3) spherical sampling, we calculated the VI and FI from the most vascularized part of the ovarian stroma at two different moments of the cardiac cycle (systole and diastole). System settings were kept constant for all of the patients (pulse repetition frequency, 0.9 kHz; gain, 0.8; and depth, 40 mm). We calculated the VI and FI ratios between systole and diastole.

The mean VI during systole (11.485%; SD, 6.7%) was significantly higher than during diastole (8.653%; SD, 5.6%; P < .0001). The mean FI values during systole (47.799 [unitless]; SD, 5.8) and diastole (47.791; SD, 6.0) were nearly identical (P = .993). The VI ratio was 1.35 (95% confidence interval, 1.28-1.42), which means that the mean VI was 35% higher during systole compared to diastole, whereas the FI during systole and diastole remained constant (FI ratio, 1.00; 95% confidence interval, 0.96-1.04). There was a high correlation between VI values during systole and diastole (r(2) = 0.94), whereas this correlation was weaker for the FI (r(2) = 0.45).

The STIC-HDF method allows assessment of 3D vascular indices throughout the cardiac cycle. Vascularization index calculation is affected by the moment of the cardiac cycle during which the measurement is taken. However, it seems that FI calculation is not affected by the cardiac cycle in the normal nondominant ovary.