Objectives: Two-dimensional (2D) matrix array is a new technology for the performance of 3-dimensional and 4-dimensional (4D) ultrasonography. In this study, we report the use of a 2D matrix array transducer for examination of fetal structures including the fetal heart.
Methods: Thirty-four fetuses without abnormalities and 19 fetuses with congenital anomalies were examined with a 2D matrix array transducer (x3-1, IE-33; Philips Medical Systems, Bothell, WA). Median gestational age was 25 6/7 weeks (range, 13 0/7-40 1/7 weeks).
Results: (1) A 360 degrees rotation and examination of selected structures was possible in the second trimester. (2) Structures were examined by maintaining the transducer in a fixed position and rotating the volume using the system trackball. (3) Dorsal and ventral parts of the hands and feet were visualized in a single volume data set, in real time, without moving the transducer. (4) Real-time en face visualization of atrioventricular valves was possible from the ventricular or atrial chambers. (5) Four-dimensional images of bones were obtained by decreasing gain settings only, with no need for cropping. (6) Four-dimensional reconstruction of vascular structures was possible with color Doppler imaging. Two limitations were identified: (1) lower resolution than mechanical volumetric transducers, and (2) narrow volume display.
Conclusions: Real-time direct 4D imaging with 360 degrees rotation for examination of fetal anatomic structures is feasible. This technology allows examination of fetal structures from multiple perspectives, in real time, without the need to move the transducer in the maternal abdomen. Further technological developments may overcome the limitations identified in this study.