Since both
two-dimensional and Doppler echocardiography use ultrasound, it
is logical to assume that both Doppler and imaging functions can
be combined into one ultrasound instrument. It is important to realize
that creation of the image takes time as does creation of the Doppler
information. The imaging device is already working as quickly as
it can to transmit, receive and then display the image data.
Therefore, time is the critical factor for any shared arrangement.
These problems are solved by switching off the imaging mode (sometimes
with the image held in memory) while the Doppler modes are in operation.
This results in either an image or Doppler choice. In some systems
a complex time sharing arrangement allows some Doppler to be carried
on while the image of the heart is still moving. When this happens,
there is always some sacrifice of the quality of the Doppler information
and frequently also in the image information. Conventional Doppler
and imaging simply do not work to their full capabilities in these
interlaced modes.
2004