IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control vol:59 issue:8 pages:1654-1663
When imaging the heart, good temporal resolution would be beneficial to capture the information of short-lived cardiac phases (in particular the isovolumetric phases). To increase the frame rate, parallel beam forming is a commonly used technique for fast cardiac imaging. Conventionally, a 4 multiple-line-acquisition (4MLA) system increases the frame rate by a factor of 4 making use of a broadened transmit beam in order to reduce block-like artifacts. As an alternative, it has been proposed to transmit an unfocused beam (i.e. plane wave or diverging wave) where a large number of parallel receive beams (i.e. 16) can be formed for each transmit. However, in order to keep the spatial resolution acceptable in these approaches, spatial compounding of overlapping successive transmits is required. As a result, the effective gain in frame rate is similar to the one of a 4MLA system. To date, it remains unclear how conventional 4MLA compares to plane wave or diverging wave imaging while operating at similar frame rate. The aim of this study was therefore to directly contrast the performance of these beam forming methods by computer simulation. In this study, the performance of 4 different imaging systems was investigated by quantitatively evaluating the characteristics of their beam profiles. The results showed that the conventional 4MLA and plane wave imaging were very competitive imaging strategies while operating at a similar frame rate. 4MLA outperformed in the near field (i.e. 10mm-50mm), while plane wave imaging had better beam profiles in the far field (i.e. 50mm-90mm). Although the diverging wave imaging performed poorest in the present study, it could potentially be improved by optimizing the settings.