HDlive Silhouette Mode With Spatiotemporal Image Correlation for Assessment of the Fetal Heart

Transcription

1 ORIGINAL RESEARCH HDlive Silhouette Mode With Spatiotemporal Image Correlation for Assessment of the Fetal Heart Toshiyuki Hata, MD, PhD, Mohamed Ahmed Mostafa AboEllail, MD, Suraphan Sajapala, MD, Mari Ishimura, RMS, Hiroshi Masaoka, MD, PhD Received August 25, 2015, from the Department of Perinatology and Gynecology, Kagawa University Graduate School of Medicine, Kagawa, Japan (T.H., M.A.M.A., S.S.); GE Yokogawa Medical Systems, Hiroshima, Japan (M.I.); and Department of Obstetrics and Gynecology, Masaoka Hospital, Hiroshima, Japan (H.M.). Revision requested September 21, Revised manuscript accepted for publication October 21, The work reported in this article was supported by a grant-in-aid for scientific research on innovative areas, Constructive Developmental Science ( ), and a research grant ( ) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan. Address correspondence to Toshiyuki Hata, MD, PhD, Department of Perinatology and Gynecology, Kagawa University School of Medicine, Ikenobe, Miki, Kagawa , Japan. toshi28@med.kagawa-u.ac.jp Abbreviations 4D, 4-dimensional; STIC, spatiotemporal image correlation; 2D, 2-dimensional doi: /ultra Objectives The purpose of this article is to present our experience with normal and abnormal fetal cardiac structures reconstructed in the HDlive silhouette mode (GE Healthcare Japan, Tokyo, Japan) with spatiotemporal image correlation (STIC). Methods Twenty-two fetuses with normal hearts and 1 fetus with a congenital heart anomaly (Ebstein anomaly) at 20 to 36 weeks gestation were studied in the HDlive silhouette mode with STIC. Results In normal fetal hearts, 4 cardiac chambers and crisscross arrangements of the pulmonary artery and aorta were clearly identified. This modality facilitated visualization of the relationships and course of the outflow and inflow tracts, thus helping the operators more effectively understand the spatial relationships among the cardiac chambers and vessels. The opening and closing of mitral, tricuspid, pulmonary, and aortic valves were ascertained in the en face view of both atrioventricular valves and great vessels. In the fetus with Ebstein anomaly, a low attachment of the tricuspid valve and an enlarged right atrium were evident. Conclusions The HDlive silhouette mode with STIC provides new visual experiences for physicians, owing to the anatomically clear depiction of fetal cardiac structures, and it may be an easier way to depict the spatial relationships among fetal cardiac chambers, great arteries, and veins. Key Words Ebstein anomaly; en face view; fetal cardiac structure; fetal echocardiography; great artery; HDlive silhouette mode; inferior vena cava; normal fetal heart; spatiotemporal image correlation; superior vena cava S ome new rendering modes of fetal echocardiography have been developed with spatiotemporal image correlation (STIC), such as HDlive (GE Healthcare Japan, Tokyo, Japan), 1,2 4-dimensional (4D) color Doppler imaging with the glass body rendering mode, 3 and HDliveFlow. 4,5 However, a detailed knowledge of the fetal cardiovascular anatomy and extensive experience are needed to master these techniques, accurately interpret the reconstructed images, and shorten the learning curve. 3,5 The HDlive silhouette mode is a new technology that provided vitreous-like clarity of the placental outline and borders, with its core transparent and fetal body folds and curves with inner structures. 6 8 Therefore, the inside of the fetal body and organs can be clearly seen, resembling holographic technology. However, there has been no study of HDlive silhouette mode evaluations of the fetal heart by the American Institute of Ultrasound in Medicine J Ultrasound Med 2016; 35:

2 To the best of our knowledge, this article is the first report on HDlive silhouette mode imaging of normal and abnormal fetal cardiac structures with STIC. Materials and Methods Twenty-two fetuses with normal hearts and 1 fetus with a congenital heart anomaly (Ebstein anomaly) at 20 to 36 weeks gestation were studied in the HDlive silhouette mode with STIC (Voluson E10; GE Healthcare Japan). The fetal age was calculated from the first day of the last menstrual period, with confirmation by first-trimester and early second-trimester sonography. Two-dimensional (2D) sonographic examinations did not reveal any fetal structural abnormalities during the examinations. Women with gestational diabetes, chronic hypertension, and maternal systemic disease and those taking antihypertensive medications were not enrolled. The study was approved by the local Ethics Committee of Kagawa University Graduate School of Medicine, and standardized informed consent was obtained from each patient. An experienced examiner (H.M.) conducted all 2D sonographic examinations and STIC volume data scans. Volume data sets of the fetal heart were acquired with STIC, which uses automated transverse and longitudinal sweeps of the anterior chest wall. With the use of curved array transducers (RM6C mechanical matrix transducer, 1 7 MHz; or em6c electric matrix transducer, 1 6 MHz), volume acquisition lasted 10 seconds for the mechanical transducer and 3 seconds for the electric transducer. Acquisition angles ranged from 30 to 40. One to 6 recordings were obtained with transabdominal 4D probes. Fetal movement necessitated repeated volume acquisitions to obtain satisfactory data. The fetus was monitored by conventional 2D sonography before the HDlive silhouette mode and STIC examination in each patient. The HDlive silhouette mode display of the fetal heart was produced after 2D sonographic examinations. The data set was stored on a 700-megabyte CD-R and could be retrieved for further analysis. All volume data for each fetus were examined, and optimal images were selected for further analysis. The 4D reconstruction was performed by using the HDlive silhouette mode and STIC. All HDlive silhouette mode examinations with STIC were performed by a single examiner (T.H.) for the data reported here. Results In normal fetal hearts, 4 cardiac chambers and crisscross arrangements of the pulmonary artery and aorta were clearly identified (Figures 1 4 and Videos 1 4). This modality facilitated visualization of the relationships and course of the outflow and inflow tracts, thus helping the operators more effectively understand the spatial relationships among the cardiac chambers and vessels (Figures 4 6 and Videos 4 6). This technique also clearly showed normal fetal aortic branches as well as different venous tributaries (Figures 3 6 and Videos 3 6). The HDlive silhouette mode combines the advantages of a spatial view of the fetal heart with the visualization of anatomic landmarks, such as the descending aorta and spine (Figure 6 and Video 6). The opening and closing of the mitral, tricuspid, pulmonary, and aortic valves were recognized in the en face view of both atrioventricular valves and great vessels (Figure 7 and Video 7). Spatial relationships among the 4 valves were also easily understood in this view. In the fetus with Ebstein anomaly, a low attachment of the tricuspid valve and an enlarged right atrium were noted (Figure 8 and Video 8). Discussion There have been only 3 reports on fetal and placental sonograms obtained with the HDlive silhouette mode. 6 8 This new technique has the ability to preserve and delineate the outline and border of the fetus and organs while showing each core s transparency, and the nature and details of their inner compositions can be clearly seen in the HDlive silhouette mode. 7,8 In this study, 4D reconstruction of the fetal heart could be done relatively easily by using the HDlive silhouette mode because of its holographic characteristics compared to previous techniques. Due to its transparency, the nature and details of the fetal chest s inner structures and intracardiac anatomy can be visualized clearly with the HDlive silhouette mode. 7 The key point is that the relationship of the heart with the descending aorta as a landmark could be easily understood because the descending aorta is long and straight and could be clearly identified by the HDlive silhouette mode. Therefore, 4 cardiac chambers and crisscross arrangements of the great arteries and the relationships and course of the outflow and inflow tracts could be clearly identified. Moreover, the spatial relationships among the 4 valves and opening and closing of atrioventricular and semilunar valves could be shown. The HDlive silhouette mode would be beneficial for detailed evaluations of the fetal heart. The HDlive silhouette mode would appear to be most useful to very high-end maternal-fetal medicine or pediatric cardiologists. However, depicting the crossing view of the major outflow tracts can be easily done in standard 2D 1490 J Ultrasound Med 2016; 35:

3 Figure 1. HDlive silhouette mode image of a normal fetal heart at 22 weeks 1 day. The aorta (Ao) arises from the left ventricle (LV), and the pulmonary artery (PA) exits from the right ventricle (RV). It can be clearly noted that the pulmonary artery crosses in front of the aorta. AoA indicates aortic arch; DA, ductus arteriosus; DAo, descending aorta; LA, left atrium; and RA, right atrium. Figure 2. HDlive silhouette mode image of a normal fetal heart at 22 weeks 1 day. The crisscross arrangement of the great arteries can be clearly identified. The spatial relationships among the cardiac chambers and vessels are evident. Abbreviations are as in Figure 1. J Ultrasound Med 2016; 35:

4 3507jum copy_layout 1 6/23/16 12:23 PM Page 1492 Hata et al HDlive Silhouette Mode of the Fetal Heart Figure 3. HDlive silhouette mode image of a normal fetal heart at 20 weeks 2 days. The origin of the aorta from the left ventricle, its 3 cephalic branches, the aortic arch, and descending aorta can be clearly recognized. BCA indicates brachiocephalic artery; LCCA, left common carotid artery; and LSA, left subclavian artery; other abbreviations are as in Figure 1. Figure 4. HDlive silhouette mode image of a normal fetal heart at 20 weeks 3 days. The spatial relationships among the cardiac chambers, outflow and inflow tracts, and vessels can be recognized. IVC indicates inferior vena cava; and SVC, superior vena cava; other abbreviations are as in Figure J Ultrasound Med 2016; 35:

5 Figure 5. HDlive silhouette mode image of the posterior view of a normal fetal heart at 20 weeks 3 days. The spatial relationships among the atrial chambers and venous vessels can be noted. Abbreviations are as in Figures 1 and 4. Figure 6. HDlive silhouette mode image of the posterior view of a normal fetal heart at 26 weeks 1 day. The spatial relationships among the fetal heart and major vessels are clearly demonstrated. The opening and closing of the mitral valve (MV) and tricuspid valve (TV) can also be seen. Ao, aorta; AoA, aortic arch; DAo, descending aorta; HV indicates hepatic vein; and Sp, spine; other abbreviations are as in Figures 1 and 4. J Ultrasound Med 2016; 35:

6 3507jum copy_layout 1 6/23/16 12:23 PM Page 1494 Hata et al HDlive Silhouette Mode of the Fetal Heart Figure 7. Consecutive HDlive silhouette mode image of an en face view of 4 cardiac valves in a normal fetal heart at 20 weeks 2 days. The opening and closing of the mitral and tricuspid valves can be clearly identified in diastole (a) and systole (b). Abbreviations are as in Figures 1 and J Ultrasound Med 2016; 35:

7 Figure 8. HDlive silhouette mode image of a fetal heart with Ebstein anomaly at 30 weeks 3 days. The spatial relationships between the low attachment of the tricuspid valve and enlarged right atrium can be noted. Abbreviations are as in Figures 1 and 6. echocardiographic examinations. Therefore, this technique has the potential to supplement standard 2D echocardiography for diagnosis of fetal heart anomalies and may assist in the prenatal evaluations of the diagnostic challenges regarding complicated heart anomalies. Moreover, the HDlive silhouette mode may be considered an additional screening technique for prenatal diagnosis of fetal heart anomalies in the future. Limitations associated with the HDlive silhouette mode with STIC are the influence of fetal movements and acoustic shadows from rib bone ossification because STIC volume acquisition lasted 10 seconds for the mechanical probe and 3 seconds for the electric probe in this study. These problems with STIC will be resolved with further technical advances. In the rendered volume data sets shown in this study using the HDlive silhouette mode, the vascular connections to the heart appeared convoluted or crooked in most images. This appearance was likely the result of heart or fetal motion artifacts. However, it may potentially lead to falsepositive diagnoses of congenital heart defects, including aortic coarctation or abnormalities in the pulmonary artery or venous connections to the heart. The HDlive silhouette rendering technique may appear prone to exaggerating motion artifacts. This technique clearly needs major improvements to be clinically useful. Further studies involving larger sample sizes with various types of congenital heart anomalies are needed to clarify the usefulness of the HDlive silhouette mode for assessment of the fetal heart. References 1. Hata T, Mashima M, Ito M, Uketa E, Mori N, Ishimura M. Threedimensional HDlive rendering images of the fetal heart. Ultrasound Med Biol 2013; 39: Hata T, Kanenishi K, Hanaoka U, Tanaka H. HDlive of the fetal heart. Donald School J Ultrasound Obstet Gynecol 2014; 8: Hata T, Kanenishi K, Mori N, Yazon AO, Hanaoka U, Tanaka H. Fourdimensional color Doppler reconstruction of the fetal heart with glassbody rendering mode. Am J Cardiol 2014; 114: AboEllail MAM, Kanenishi K, Tenkumo C, Kawanishi K, Kaji T, Hata T. Transvaginal 4D color Doppler in antenatal diagnosis of truncus arteriosus in the first trimester of pregnancy. Ultrasound Obstet Gynecol 2015; 45: AboEllail MAM, Kanenishi K, Tenkumo C, et al. Four-dimensional power Doppler sonography with the HDlive silhouette mode in antenatal diagnosis of a right aortic arch with an aberrant left subclavian artery. J Ultrasound Med 2016; 35: AboEllail MAM, Kanenishi K, Mori N, Kurobe A, Hata T. HDlive imaging of circumvallate placenta. Ultrasound Obstet Gynecol 2015; 46: AboEllail MAM, Hanaoka U, Numoto A, Hata T. HDlive imaging of a giant fetal hemangioma. J Ultrasound Med 2015; 34: AboEllail MAM, Tanaka H, Mori N, Hanaoka U, Hata T. HDlive silhouette mode in antenatal diagnosis of jejunal atresisa [published online ahead of print September 4, 2015]. Ultrasound Obstet Gynecol. doi: /uog J Ultrasound Med 2016; 35: