Tissue Doppler Imaging Flashcards
Returning echoes are constantly bombarding the computers in the ultrasound machine. Until recently filters were in place to eliminate low frequency high amplitude info received from myocardial reflection of sound. Reflection of sound from blood is high frequency and low amplitude.
Normal blood flow is typically less than …… cm/sec while myocardial velocity of motion is usually less than ……. cm/sec.
Returning echoes are constantly bombarding the computers in the ultrasound machine. Until recently filters were in place to eliminate low frequency high amplitude info received from myocardial reflection of sound. Reflection of sound from blood is high frequency and low amplitude.
Normal blood flow is typically less than 200 cm/sec while myocardial velocity of motion is usually less than 20 cm/sec.
TDI utilizes this low frequency high amplitude sound to record myocardial velocity during systole and diastole. PW TDI can be obtained in real time by placing a gate over a portion of myocardium and recording positive and negative ………………
TDI utilizes this low frequency high amplitude sound ro record myocardial velocity during systole and diastole. PW TDI can be obtained in real time by placing a gate over a portion of myocardium and recording positive and negative frequency shifts.
Color TDI is obtained by placing a sector of color over the myocardium and saving a video loop of info for off line analysis. After retrieving the color TDI study from computer memory, a gate is placed anywhere color was superimposed over the myocardium, and its corresponding ………and………….movements are displayed.
After retrieving the color TDI study from computer memory, a gate is placed anywhere color was superimposed over the myocardium, and its corresponding systolic and diastolic movements are displayed.
Advantage of color TDI?
The myocardial motion from the entire area of myocardium under the color sector can be analyzed from one stored loop of video. Gates simply need to be placed over different areas of myocardium under the color sector, and motion info is displayed. Fig 3.65
Info can be displayed simultaneously from different parts of the ventricle at the same point in the cardiac cycle.
Drawback with PW TDI?
PW TDI provides info only from one gate location in RT, and the gate must be moved to another location to interrogate any other area of the myocardium.
Valuable thing about PW TDI?
Myocardial velocity obtained from PW TDI is usually higher than the velocities obtained off line with color TDI. This is because of better temporal resolution resulting in higher quality velocity information.
Imaging plane used: Can be obtained from a variety of imaging planes. Such as?
Longitudinal myocardial velocity is obtained from apical 4 ch views of the heart. The lateral walls of the left and right ventricular chamber or the inter ventricular septum are positioned on the image so that the color sector or Doppler cursor line up parallel with the length of the wall or septum.
Fig 3.65, 3.66, 3.67
The loop is stored anywhere under the color sector at a later time. PW TDI is immediately obtained by placing the Doppler gate at any point along the wall or septum.
Circumferential radial myocardial velocity can be obtained from right parasternal transverse or sagittal imaging planes (Fig 3.67)
Circumferential radial myocardial velocity can be obtained from right parasternal transverse or sagittal imaging planes (Fig 3.67)
TDI is an option that can be added to ultrasound equipment. Theoretically, however, by manipulating the filters and changing the pulse repetition frequency, PW tissue velocity info can be obtained from equipment without the added option. How?
Turn down the filter settings while in spectral Doppler mode and change the PRF (velocity range) to display low velocity flow of 20 to 30 cm/sec. Place the PW gate over the myocardium and press the spectral display button to see the spectral image of myocardial motion under the gate.
Spectral appearance:
Place the baseline in the middle of the spectral display.
Systolic contraction (S´or Sm -liten nersänkt m)- (sometimes labeled Sa -liten nersänkt a if the gate is placed at the annulus of an AV valve) results in a positive frequency shift. Diastolic motion of the myocardium is negative and has 2 phases: early diastolic motion (E´or Em) (sometimes labeled Ea if the gate is placed at the AV annulus).
Systolic contraction (S´or Sm -liten nersänkt m)- (sometimes labeled Sa -liten nersänkt a if the gate is placed at the annulus of an AV valve) results in a positive frequency shift. Diastolic motion of the myocardium is negative and has 2 phases: early diastolic motion (E´or Em) (sometimes labeled Ea if the gate is placed at the AV annulus) Fig 3,65, 3,66, 3,67.
Between the diastolic and systolic waves, ……………and …………… times can be identified. These systolic and diastolic waves are similar in appearance with slight changes in velocity whether the motion is recorded from longitudinal or circumferential fibers.
Between the diastolic and systolic waves, isovolumic contraction and relaxation times can be identified. These systolic and diastolic waves are similar in appearance with slight changes in velocity whether the motion is recorded from longitudinal or circumferential fibers.
Fast heart rates, just as with transmittal and trans tricuspid flows will result in superimposed E´and A´.
Fast heart rates, just as with transmittal and trans tricuspid flows will result in superimposed E´and A´. Fig 3.68
