Reference Values for Doppler Parameters of the Fetal Anterior Cerebral Artery throughout Gestation

Abstract

Aim: To construct normal reference values for Doppler parameters in 2 anatomical segments of the fetal anterior cerebral artery (ACA) throughout pregnancy. Methods: The ACA was evaluated in 373 normally growing fetuses from 20 to 40 weeks of gestation. The first segment of the ACA (ACA-S1) was recorded just after its origin from the internal carotid artery in the same plane as the middle cerebral artery (MCA). The second segment (ACA-S2) was recorded distal to the outlet of the anterior communicating artery. Results: The ACA pulsatility index (PI) behaved similarly in both segments, with a constant increase until 28 weeks followed by a decrease until the end of pregnancy [ACA-S1 PI = 3.49 – 0.37 × gestational age (GA) – (0.0063 × GA²), SD = 0.6 – 0.061 × GA – (0.001 × GA²); ACA-S2 PI = 1.54 – 0.22 × GA – (0.0037 × GA²), SD = 0.206 + (0.0037 × GA)]. Peak systolic velocities in both segments showed a constant increase from 20 to 40 weeks of gestation. No significant differences were found between the 2 segments with regard to any Doppler parameter. However, the angle of insonation and the time spent on examination were significantly lower and reproducibility was better for ACA-S1. Conclusion: Despite showing similar Doppler values, ACA-S1 has a higher reliability than ACA-S2 and can be recorded in the same anatomical projection as the MCA.

Normal reference ranges of fetal regional cerebral blood perfusion as measured by fractional moving blood volume

“…In this study the relative values of brain tissue perfusion increase slightly through the third trimester. These findings are consistent with those of previous studies using cerebral spectral Doppler ultrasound, which have reported decreasing impedance in the MCA and anterior cerebral artery as gestation progresses30–33. Similarly, other studies using 3D‐PDU have qualitatively assessed fetal cerebral blood perfusion and reported that brain perfusion values increase with gestational age9–12.…”

Changes in Central and Peripheral Circulation in Intrauterine Growth-Restricted Fetuses at Different Stages of Umbilical Artery Flow Deterioration: New Fetal Cardiac and Brain Parameters

“…fetal brain circulation was examined in an axial plane at the level of circle of Willis. The ACA was then recorded in its two segments: ACA1, between its origin from the internal carotid artery and the anterior communicating artery, and ACA2, just after the anterior communicating artery [12] but before becoming the pericalloseal artery. The MCA was registered at the proximal segment after its origin from the circle of Willis.…”

“…In order to adjust for gestational age, all Doppler values were expressed in z-scores (SD values from the mean) [10,12,13,14,15,16]. Normality was considered between –1.645 z-scores (5th centile) and +1.645 z-scores (95th centile).…”

Middle versus anterior cerebral artery Doppler for the prediction of perinatal outcome and neonatal neurobehavior in term small‐for‐gestational‐age fetuses with normal umbilical artery Doppler

“…For the ACA, the Doppler gate was placed immediately after the origin of the ACA from the internal carotid artery. Either the MCA‐PI or the ACA‐PI values below the 5 th centile were considered indicative of cerebral blood flow redistribution and were reported as abnormal18, 21.…”