Simultaneous real‐time imaging of four‐chamber and left ventricular outflow tract views using xPlane imaging capability of a matrix array probe

• Published in: Ultrasound in obstetrics & gynecology Vol. 37; no. 3; pp. 302 - 309
• Main Authors: Yuan, Y., Leung, K. Y., Ouyang, Y. S., Yang, F., Tang, M. H. Y., Chau, A. K. T., Dai, Q.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.03.2011; Wiley; Wiley Subscription Services, Inc
• Subjects: Algorithms; Biological and medical sciences; Cardiovascular system; congenital heart defect; Echocardiography, Three-Dimensional - methods; Feasibility Studies; Female; fetal echocardiography; Fetal Heart - diagnostic imaging; Fetal Heart - embryology; Fetal Heart - physiopathology; Fetuses; Gestation; Gynecology; Gynecology. Andrology. Obstetrics; Heart; Heart Defects, Congenital - diagnostic imaging; Heart Defects, Congenital - embryology; Heart Defects, Congenital - physiopathology; Heart Ventricles - diagnostic imaging; Heart Ventricles - embryology; Humans; Image Processing, Computer-Assisted; imaging; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Obstetrics; outflow tract; Pregnancy; Probes; Prospective Studies; Reproducibility of Results; Stroke Volume - physiology; Ultrasonic investigative techniques; Ultrasonography; Ultrasound; Ventricle; Ventricular Function, Left - physiology; Sonography; Heart; Echocardiography; Gynecology; Cardiovascular disease; fetal echocardiography; Probe; Real time; Obstetrics; Left ventricle; outflow tract; congenital heart defect; Pregnancy; Fetus; Congenital cardiopathy
• ISSN: 0960-7692; 1469-0705; 1469-0705
• DOI: 10.1002/uog.8883

Objectives To determine the feasibility and reliability of using xPlane imaging to examine simultaneously the four‐chamber and left ventricular outflow tract (LVOT) views in real time, to assess rotation angles from the four‐chamber view to the LVOT view, and to investigate factors affecting the angles. Methods In 145 fetuses at 11–37 weeks' gestation, we visualized the four‐chamber view in one of three cardiac positions: a subcostal view with the apex at the 3 or 9 o'clock position; an apical view with the apex at the 12 or 6 o'clock position; or a view with the fetal heart apex midway between these two positions. We then used the rotation function of xPlane imaging, using the four‐chamber view as the reference plane, to visualize the LVOT view simultaneously in real time on the secondary image plane, on the right side of the split screen, by rotating a reference line from 0° with a rotation step of 5°. The rotation angle necessary for the first appearance of LVOT was recorded as the first rotation angle. The reference line was then rotated until the LVOT was just out of view, and this last rotation angle was recorded as the second rotation angle. The difference between these two angles was recorded as the angle span of the LVOT display. Reliability was assessed by intraclass correlation coefficient (ICC). Results Of the 145 fetuses examined, 29 had cardiac defects. Using xPlane imaging, the LVOT was visualized successfully after 14 weeks in 95.1% of cases. The first and second rotation angles varied significantly with cardiac position (P < 0.001); when the fetal heart was examined using a subcostal approach with the apex at the 3 or 9 o'clock position, the first rotation angle was smaller than that at the apical view for normal hearts (20° vs. 50°, P < 0.001). There was also a significant difference for the second rotation angle and for the angle span, between fetuses with and without normal LVOT (P = 0.038 and 0.006, respectively). Regarding intra‐ and interobserver reliability for measurement of first and second rotation angles, the ICCs were high (range, 0.847–0.980). Conclusion Using xPlane imaging, it is feasible to examine simultaneously the four‐chamber and LVOT views in real time, and measurement of the rotation angles between these two views is reproducible. The rotation angles depend on the position of the fetal heart, and the normality of the LVOT. Proposed algorithms for examination of the fetal heart with three‐/four‐dimensional ultrasonography may need to be adapted to optimize visualization of the standard planes. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.