TMS
Didactic Muse
Page 15
Imaging Ultrasound Cont.
mitral valve
TIME MOTION MODE
is a dual-flap
valve in the heart
that lies between
the left atrium (LA)
and the left
ventricle (LV).
A representation of TM is shown in fig. 16. In the top there is a probe that sends
an ultrasound beam that travels through the spheres A, B, and C. This beam
does not move like in B mode from line to line. Only one line is needed to form
the T mode, and the possible motion of the line is done by decision of
the operator. Sphere A moves up and down continuously between the points A1
and A2. Sphere B is not moving and C is also moving up and down
continuously but between the points C1 and C2. The space between C1
and C2 is wider than the space between A1 and A2. At the right side, there
are three graphics that represent, in the vertical axis, the amplitude of the
movements of the spheres and, in the horizontal axis, the time, like an
electrocardiograph. This is the way the TM mode appears on screen. In TM
the screen does not show an image which has the real shape of the of the
human organs, vein, etc., like in B mode. TM only obtains information of
the structures in movement like the spheres A and C, in structures like the
valves of the heart. As the sphere B is not in movement, the T mode does not
give information of B. The importance of the TM mode is that there is no possibility to obtain a true measure of organs in movement, like the valves of the
heart. It is important for the physicians to know the maximum aperture
and closing of the mitral valve, for doing measurements, the image is frozen, to permit location of the measurements points. For a valve which is
opening and closing continuously it is almost impossible to freeze at the
right time when the valve is complete closed or completed opened so
there is no possibility to obtain a confidence m