Three-dimensional echocardiography: an accurate technique for cardiac quantification

textabstractCardiac ultrasound has become the dominant imaging technology in clinical cardiology. Two-dimensional echocardiography (2DE) gained widespread use and allows rapid and comprehensive evaluation of anatomy and function by providing tomographic cardiac views recorded from transthoracic (TIE) or transesophageal (TEE) acoustic windows. However, the diagnosis of a cardiac disorder is based on a mental spatial reconstruction process of these views into their correct geometry. This process is not always easy and accurate particularly in complex congenital heart disease and in patients with coronary artery disease and distorted ventricles. Three-dimensional echocardiography (3DE) obviates these limitations and is able to provide more accurate quantitative and qualitative information in complex disorders. The first attempt to obtain 3DE images for cardiac diagnosis and quantification started two decades ago. These were computed from a series of nonparallel echocardiographic images using either an articulated device or an acoustic ranging technique using multiple spark gaps for spatial registration. However, this approach was tedious and time consuming. In addition, cycle selection, border digitizing and tracing together with the computer analysis would take several days. With the revolutionary advances in the computer technology, 3DE acquisition is considerably shortened with optimal spatial and temporal registration by using computer controlled transducer systems. Approaches to 3DE are: • Random acquisition with external reference (mechanical, acoustic and electromagnetic). • Predetermined acquisition with internal reference (linear, fan like and rotational). • Real time acquisition (pyramidal volumetric scan). Real time volumetric scan is by definition the ideal technique for 3DE. Initial results are promising, but further improvement in image quality is needed for routine clinical application. In practice the most commonly used methods arc the random acquisition and the predetennined rotational acquisition technique