Catching the Fetal Heart Volume (STIC)-USA

Welcome to the Siemens Catching the Fetal Heart Volume (STIC) tutorial. Before we begin, I would like to introduce myself briefly. I will be your guide to help you understand the information presented in this tutorial. During the course, I will be giving you a lot of detailed information.   Click the information icon in the lower left corner for tutorial Navigation Tips.   This tutorial has more information in the form of links placed on the page.  To successfully complete this course, please view all available content.   We hope you enjoy our tutorial.    Click on the right arrow to continue. Upon completion of this tutorial, the learner will be able to:   1. Identify structures seen in the fetal heart.   2. Explain acquisition of a STIC data set. Congratulations! You have completed the Catching the Fetal Heart Volume (STIC) tutorial. Listed below are the key points presented in this tutorial. Take time to review the material before you try the final quiz.   Download and print a copy of the detailed Course Review   In this tutorial you have learned to   1. Identify structures seen in the fetal heart. 2. Explain acquisition of a STIC data set. Please note that the learning material is for training purposes only!   For the proper use of the software or hardware, please always use the Operator Manual or Instructions for Use (hereinafter collectively “Operator Manual”) issued by Siemens Healthineers. This material is to be used as training material only and shall by no means substitute the Operator Manual. Any material used in this training will not be updated on a regular basis and does not necessarily reflect the latest version of the software and hardware available at the time of the training.   The Operator Manual shall be used as your main reference, in particular for relevant safety information like warnings and cautions. Note: Some functions shown in this material are optional and might not be part of your system. The information in this material contains general technical descriptions of specifications and options as well as standard and optional features that do not always have to be present in individual cases.   Certain products, product related claims or functionalities described in the material (hereinafter collectively “Functionality”) may not (yet) be commercially available in your country. Due to regulatory requirements, the future availability of said Functionalities in any specific country is not guaranteed. Please contact your local Siemens Healthineers sales representative for the most current information. The reproduction, transmission or distribution of this training or its contents is not permitted without express written authority. Offenders will be liable for damages.   All names and data of patients, parameters and configuration dependent designations are fictional and examples only. All rights, including rights created by patent grant or registration of a utility model or design, are reserved.   Copyright © Siemens Healthcare GmbH, 2018 Selecting the ► continues this course and confirms you have read and understand this disclaimer. Congenital heart disease (CHD) represents a global health problem comprising almost a third of major malformations. Though rates vary by geography, approximately eight children per 1000 live births show some degree of heart defects.1 The most common structural defect is in the interventricular septum with the atrial septal defect a close second.1, 2   The cause of CHD is as varied as each individual. Defects may simply be idiopathic, genetic, or due to environmental or maternal factors such as diabetes mellitus, infections, or drug use.1  Data show good news as with a steady increase in the adult population with CHD due to improving diagnostic and interventional care.1-3 The first step in diagnosing defects is our ability to recognize the normal heart structures during the second trimester (18 – 22 weeks) obstetric exam. Learn More about Fetal Heart Views Learn More about Fetal Heart Views Tab TitleText4-chamberThe 4-chamber heart is the mainstay of any prenatal exam. This view allows us to determine that the heart occupies approximately one- third of the chest. The majority of the normal heart sits at a 45-degree angle within the transverse chest with the apex pointed to the left. When imaging the heart, verify a left-sided heart and stomach (Figure 1) to verify situs and the absence of pericardial effusion.5   Figure 1. This mid-sagittal image of the fetal thorax and abdomen show the stomach (asterisk) and heart apex (arrow) on the same side. This view confirms the heart and stomach are on the same side.   The two atria have about the same size with the foramen ovale flap extending into the left atrium (LA) (Figure 2).  Ensure continuity of the atrial septum at the crux (primum) and the entrance of the pulmonary veins into the LA4, 5.   The two ventricle walls have the same thickness and are also close to equal in size (Figure 2). We see the moderator band in the right ventricle at the apex. Finally, check that the ventricular septum is free of defects throughout the entire length.5   Figure 2. The atria (dots) and ventricles (asterisks) image on the 4-chamber view of the heart. The aorta (arrow) lies between the left atrium and spine. A final structure to document is the atrioventricular (AV) junction and the motion of the tricuspid (TV) and mitral (MV) valves.7 Real-time imaging and the cineloop function allows us to observe the opening and closing of the AV valves.  Keep in mind the normal TV inserts closer to the apex than the MV.LVOTThe left ventricular outflow tract (long axis view of the aorta) allows us to view the aortic root as it extends from the interventricular septum (IVS). The angle of incidence of the IVS and transmitted beam is close to 90 degrees in this view providing the optimal angle to interrogate the septum for defects.5 An M-mode tracing through the ventricle documents the fetal heart rate.   This image of the LVOT shows the right atrium (RA; asterisk), left ventricle (LV; dot), right pulmonary artery (closed arrow), aortic arch (arrowhead), and the superior vena cava (SVC; open arrow). The aortic valve appears as a linear structure within the aortic root indicating this image was taken during ventricular diastole. RVOTObtaining a view of the right ventricular outflow (RVOT), either on the long or short axis, confirms the pulmonary artery origin at the RV.5, 7 The pulmonary valve moves within the artery proximal to the right and left pulmonary artery bifurcation.   The short-axis RVOT view shows a central aorta (dot) with the pulmonary artery curving at a 90-degree course (arrowhead).  In this image we can see the closed aortic valve cusps as a linear echo within the aortic root. This view allows visualization of the pulmonary valve (PV; arrow) and TV. 3-VesselThe three-vessel (3V) plus the three-vessel and trachea (3VT) views show the relationship, and presence of, the pulmonary artery, aorta, SVC, and trachea.5 To obtain these views, image the fetal chest on a transverse plane superior to the base of the heart.7   Figure 1. The 3V view shows the pulmonary artery (PA; green), aorta (pink), and the SVC (yellow) anterior to the spine (yellow triangle).    Figure 2. The 3VT view has a characteristic ‘v’-shaped arrangement with the ductal arch (green) and aorta (pink) located to the left of the trachea (green dot). SVC – yellow. Multiple guidelines agree the minimum fetal heart exam includes the four-chamber, left ventricular outflow tract (LVOT), right ventricular outflow tract (RVOT), and three-vessel views.4-6 Let’s take a look at these views on the 2D-mode image.   Click on the icon below to view fetal heart views.   Click the right arrow to continue. Clinicians using ultrasound to image the fetal heart are very aware of the limited time available to obtain images. The normal fetal activity of rolling, kicking, and breathing adds complexity to the heart portion of the exam. The difficulty level increases in the presence of a heart defect which often requires viewing of a cineloop to determine diagnosis. As a result, cardiac malformations are the most commonly overlooked anomalies during the obstetric exam.8   The acquisition and display of the 3D data set as a MultiPlanar rendering (MPR) or MultiSlice format helps with cardiac imaging. However, the 3D image lacks the element of time.9 Spatiotemporal image correlation (STIC) software combines the three orthogonal planes (X, Y, & Z) using anatomic location changes to create the 4D data set.9, 10 The result is the ability to create a cineloop and still images from any plane from one acquisition. The aim of acquiring a STIC image is the creation of a moving, 4D cineloop of the fetal heart. To accomplish this goal, software uses structural changes within the dataset.   Data acquisition begins with an automated sweep through the volume. The result is many, sequential 2D images of the fetal heart. Depending on technical factors, there may be as many as 1500 2D-mode images!11, 12 Completion of data acquisition triggers analysis of the 2D images. The first step is to determine the frequency (spatio-) and length (temporal) of information within the data set. The ultrasound system correlates a structure between frames within the 3D data set.12 For example, when ventricles relax (left image), the volume will be larger. Ventricular contraction (right image) produces a smaller volume. The system groups the images based on occurrence time within the cardiac cycle regardless of their location within the data set. 11, 12   Instead of utilizing a traditional ECG for cardiac timing, the system uses the spatial coordinates of each image to identity the heart cycle. In this example we show two volumes, one with all images obtained during systole (left image) and a second during diastole (right image). The system uses the spatial coordinates of each image to determine the location of that image in the volume. This allows for calculation of an average fetal heart rate.10-12 We are using only two sets of images but with 1500 images there are many volumes to correlate. The STIC software then creates the cineloop based on spatial and temporal changes found within the data set.12   The STIC volume quality depends on multiple factors which include fetal position, fetal activity, maternal body habitus.8 Artifacts seen with 2D-mode imaging such as shadowing and reverberation, also decrease image quality in the data set.10 Obtaining multiple volumes help with collecting the artifact-free data set.10 The benefits of performing the STIC acquisition far outweigh the pitfalls. These include:8 Decreases in exam and dwell time. Visualization of any view on any plane. Ability to review the study outside of the patient exam. Observation of spatial relationships with in the heart. The potential for cineloop and frame-by-frame analysis of the heart. Facilitates efficient sharing of data sets between geographically independent specialists. Click on the icon below to learn how to optimize the 2D-mode and fetal STIC acquisition parameters. To review the acquisition process, click here. Learn How to Optimize the STIC Volume Learn How to Optimize the STIC Volume Tab TitleTextOptimize the 2D image8, 131. Choose the highest frequency transducer possible for the exam. 2. Select the fetal echo preset.  3. Adjust the overall gain to an optimal level. 4. Increase contrast (i.e. low dynamic range or gray map) to separate heart structures. 5. Decrease persistence. 6. Narrow the scanning sector and depth to increase both the frame rate and line density. 7. Use single focal zone positioned at or deep to the heart. 8. Magnify anatomy to fill the sector. 9. Whenever possible, move the transducer to position the heart apex towards the 11 o’clock position and the spine at the 6 o’clock position. 10. With the heart in the above position, the apex points to the left of the image.   The image on the left shows a reduced sector size when imaging the RVOT. Decreasing the sector width increases the line density and thus, image detail. The image on the right is the same view using the write zoom function.Optimize the STIC Volume8, 131. Place the region of interest (ROI) over the heart. 2. Use the smallest possible volume of interest (VOI) to increase temporal resolution. Restricting the VOI to the fetal chest and heart includes the anatomy while maximizing frame rate. 3. Select the smallest acquisition angle possible. As a guideline, use an angle that is 5 degrees larger than the fetal age. For example, if you image a 30-week fetus, start by using a 35-degree angle. 4. Balance the acquisition time with detail. The larger the data set the better the spatial detail; however, fetal activity determines the speed needed to acquire the data set. The active fetus requires a faster acquisition time while a calm fetus allows for a slower time. 5. Suspend maternal breathing keeping the transducer stationary during acquisition.   This image of the fetal profile shows the ROI with a solid green outline. This represents the entire area included in the acquired volume. The VOI lies within the square brackets ( ¬ ) showing the boundaries of the rendered volume. The dotted line in the anterior portion of the ROI is the rendered view and direction.Evaluating the Data Set12, 131. Is there a 4-chamber view with minimal or no shadowing within the ROI on the A plane? 2. If acquisition occurs using the 4-chamber view, does the B plane show a transverse heart view? 3. Did the fetus move or breath during acquisition? 4. Are there multiple data sets free of artifacts? 5. Are the ventricles and atria approximately the same size? 6. How do the lungs compare? Are they symmetrical? 7. Does the spine show three ossification centers on the transverse view? 8. Did the ROI include all the heart structures? 9. Does the cineloop show artifactual motion? Tip: View at half the acquisition speed.     This image shows a multiPlanar rendering (MPR) with the 4-chamber view on the A or acquisition plane (upper left) and the orthogonal RVOT in the upper right.   Explore the links below for the Glossary, References, and Further Reading opportunities. Glossary Glossary 3D (three-dimension) – The addition of depth or Z plane using multiple 2D-mode images.   4D (four-dimension) – The inclusion of time in the 3D data set resulting in a real-time image.   Cineloop – A collection of images displayed synchronously to appear as a video clip.   Crux of the heart – The junction of the heart chambers at the interatrial and interventricular septum and the atrioventricular valves.   Foramen ovale – Opening in the interatrial septum seen in the fetus allowing of bypass of the lungs during prenatal life.   Moderator Band – Attachment of the anterior papillary mucle from the interventricular septum to the apex of the right ventricle.   Orthoginal – At right angles.   Temporal – Relating to time. References / Further Reading References / Further Reading 1. van der Linde, D., Konings, E.E.M., Slager, M.A., Witsenburg, M., Helbing, W.A., Takkenberg, J.J.M., and Roos-Hesselink, J.W. (2011). Birth prevalence of congenital heart disease worldwide: a systematic review and meta-analysis. Journal of the American College of Cardiology. 58(21): 2241-2247.   2. Marelli, A.J., Mackie, A.S., Ionescu-Ittu, R., Rahme, E., and Pilote, L. (2007). Congenital heart disease in the general population changing prevalence and age distribution. Circulation. 15(2): 163-172.   3. Triedman, J.K. and Newburger, J.W. (2016). Trends in congenital heart disease: the next decade. Circulation. 133(25): 2716-2733.   4. BCCA. (2012). Fetal cardiology standards, in BCCA Fetal Cardiac Standards, BCCA: United Kingdom.   5. Carvalho, J.S., Allan, L.D., Chaoui, R., Copel, J.A., DeVore, G.R., Hecher, K., . . . Yagel, S. (2013). ISUOG Practice Guidelines (updated): sonographic screening examination of the fetal heart. Ultrasound in Obstetrics & Gynecology. 41(3): 348-359.   6. Salomon, L., Alfirevic, Z., Berghella, V., Bilardo, C., Hernandez Andrade, E., Johnsen, S., . . . Lee, W. (2011). Practice guidelines for performance of the routine mid-trimester fetal ultrasound scan. Vol. 37. 116-126.   7. Drose, J.A. (2010). Scanning: indications and technique. In Drouse, J.A., (Eds.), Fetal Echocardiography  (pp. 15-72). St. Louis: Saunders Elsevier.   8. Lunsford, B. (2017). 3D and 4D imaging in obstetrics and gynecology. In Stephenson, S.R. and Dmitrieva, J., (Eds.), Diagnostic Medical Sonography: Obstetrics and Gynecology  (pp. 805-836). Philadelphia: Wolters Kluwer.   9. Morris, S.A., Ayres, N.A., Espinoza, J., Maskatia, S.A., and Lee, W. (2016). Sonographic evaluation of the fetal heart, in Callen's Ultrasonography in Obstetrics and Gynecology, Norton, M.E., Scoutt, L.M., and Feldstein, V.A., Editors, Elsevier: Philadephia 371-459   10. Adriaanse, B.M.E., van Vugt, J.M.G., and Haak, M.C. (2016). Three- and four-dimensional ultrasound in fetal echocardiography: an up-to-date overview. Journal Of Perinatology. 36: 685. 11. Yeo, L. and Romero, R. (2016). How to acquire cardiac volumes for sonographic examination of the fetal heart: part 1. Journal of Ultrasound in Medicine. 35(5): 1021-1042.   12. DeVore, G.R., Falkensammer, P., Sklansky, M.S., and Platt, L.D. (2003). Spatio-temporal image correlation (STIC): new technology for evaluation of the fetal heart. Ultrasound in Obstetrics and Gynecology. 22(4): 380-387.   13. Yeo, L. and Romero, R. (2016). How to acquire cardiac volumes for sonographic examination of the fetal heart: part 2. Journal of Ultrasound in Medicine. 35(5): 1043-1066.