The application of color power angiography to the longitudinal quantification of blood flow volume in the fetal middle cerebral arteries, ascending aorta, descending aorta, and renal arteries during gestation

OBJECTIVE: This study was undertaken to determine by means of color power a ngiography the longitudinal changes in the diameters and the flow volumes o f 4 major fetal arteries during gestation. STUDY DESIGN: The middle cerebral artery, the ascending aorta, the descendi ng aorta, and the renal arteries in 81 appropriate-for-gestational-age fetu ses were examined longitudinally between 24 and 38 weeks' gestation by mean s of color power angiography. In addition to measurement of the diameters o f these arteries, Doppler velocimetry was performed. Flow volume was calcul ated from the cross-sectional areas of the arteries and the velocity integr al of the Doppler waveforms. RESULTS: The mean (+/-SD) gestational age at delivery and birth weight were 39.8 +/- 1.6 weeks and 3326 +/- 345 g, respectively. The diameters and flo w volumes of all the arteries increased significantly as gestational age ad vanced. Flow volume increased from 39 +/- 19.0 mL/min to 140 +/- 63.9 mL/mi n in the middle cerebral artery, from 216.2 +/- 77.6 to 937.4 mL/min in the ascending aorta, from 124.4 +/- 76.6 to 390.0 mL/min in the descending aor ta, and from 27.5 +/- 16.8 to 80.3 +/- 57.3 mL/min in the renal arteries. W hen blood flow volume was adjusted to milliliters per kilogram body weight, an initial significant fall in blood flow was seen in all the vessels to a minimal level at 30 weeks' gestation; blood flow rose thereafter, although not significantly, until term. The ratios of flow volume in the ascending aorta to those in the other vessels increased with gestation, with the high est ratio being that between the ascending aorta and the renal arteries. CONCLUSION: Identification of fetal arteries with color power angiography i s easy and highly sensitive. The distributions of blood flow in various fet al arteries exhibited regional differences, with significantly more blood f low to the brain. These normative baseline values may be useful in the diag nosis of congenital cardiac anomalies and also in the diagnosis and monitor ing of fetuses with intrauterine growth restriction.