INITIAL CLINICAL-EXPERIENCE - WITH DYNAMIC 3-DIMENSIONAL ECHOCARDIOGRAPHY (ECHO-CT) IN CHILDREN WITH CONGENITAL HEART-DEFECTS

A prototype computed tomographic echocardiographic imaging probe was examined for its usefulness in diagnosing congenital heart disease in pediatric patients. A 64-element, phased-array, 5 Mhz, echocardiographic transducer mounted on a sliding carriage was used transthoracically on various positions of the chest. The transducer moves from the outflow tract to the apex of the heart in .5 to 1.3 mms increments and records a tomographic slice of the heart at each increment level. Parallel images are recorded at a frame rate of 25-30 images/s and are ECG- and respiration-gated. At each level a complete cardiac cycle is recorded. The images are digitized and stored in the image processing computer which reconstructs the anatomic structures of the heart in a three-dimensional format by means of different gray-scales. 54 pediatric patients with a variety of congenital heart defects were examined. Good quality echocardiographic pictures were obtained in all but 2 of the 54 patients. In these, three-dimensional reconstruction of the heart-was possible from transthoracically acquired echocardiographic studies. The recorded cardiac chambers and valves could be displayed in a three-dimensional format in real-time (four-dimensionally). One could also display the heart in real-time in any desired plane and in up to 5 planes simultaneously without having to change the transducer position on the chest. Different parts of the heart could be displayed in a view similar to the one a surgeon has during the operation. Between 40 and 130 tomographic slices per patient were recorded. Image acquisition took 3-5 min and three-dimensional reconstruction of various cardiac structures took 20-90 min. We conclude that the computed tomographic imaging probe facilitates acquisition of echocardiographic data as multiple planes can be obtained without changing the position of the transducer-carrying carriage. Display of three-dimensional structures of the heart may enhance our understanding of cardiac anatomy.