THE GEOMETRICAL RELATIONSHIP BETWEEN THE HUMAN ESOPHAGUS AND LEFT-VENTRICLE - IMPLICATIONS FOR 3-DIMENSIONAL ULTRASONIC-SCANNING

To establish design parameters for a transesophageal ultrasonic probe to image the left ventricle (LV) in three dimensions, the geometrical relationship between the esophagus and the heart was studied in comput ed tomographic sections of ten humans. Points describing the esophagea l centerpoint and the left-ventricular endocardium were digitized. Alg orithms were developed to determine from any esophageal viewpoint the ranges of motion required to cover the LV with four modes of scanning; transverse oblique, longitudinal oblique, rotary and linear. Longitud inal oblique scanning was the only single-degree-of-freedom method tha t allowed complete imaging of the LV in all patients. However, for bot h conventional and three-dimensional LV imaging, the most promising pr obe design appears to be a rotary scanning probe with an added degree of freedom to tilt the axis of rotation +/- 29-degrees away from an ax is perpendicular to the local esophageal axis.