Data processing for a fast rotating phased array real-time 3D acquisition unit

A fast rotating phased array transducer was designed in order to scan a conical section of the heart at high scan rates. Typical rotation rate is 240-480 rpm. Data is acquired in a period of 10 seconds using a GE Vingmed System V mainframe and stored in a PC as a sequence of frames in their raw (polar) format, i.e. range versus scan angle. The frames are linearly related to rotation angle. The data set is thus fully described in a spherical coordinate system. The contours of the left ventricle may be traced in the raw data frames without any scan conversion. The LV volume, contained in the sequence of contours along the azimuth direction in the spherical domain, can be obtained directly using a spherical volume integral. Another application of processing in the spherical domain is the fusion of multiple heartbeats into a synthesized single heartbeat. This can be achieved by realignment of the spherical data in the azimuth range using the ECG as synchronization. Asynchronous probe rotation produces a random interleaved volume sampling. We propose that the construction and analysis of three-dimensional data sets obtained from a fast rotating sector scanner is performed in the spherical coordinate system, produced by the probe itself. The procedure is efficient, accurate and time saving.