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| Tissue Doppler ： ウィキペディア英語版 |
Tissue Doppler echocardiography
Tissue Doppler echocardiography (Also called Tissue Doppler Imaging - TDI or Tissue Velocity Imaging - TVI) is a Medical ultrasound technology mainly used in Echocardiography that measures the velocity of the heart muscle or myocardium through the phases of one or more heartbeats by the Doppler effect (frequency shift) of the reflected ultrasound. The technique is the same as for Doppler echocardiography, measuring flow velocities. Tissue signals however, have higher amplitude and lower velocities, and the signals are extracted by using different filter and gain settings. Like Doppler flow, Tissue Doppler can be acquired both by spectral analysis (Spectral density estimation) as pulsed Doppler 〔Isaaz K, Thompson A, Ethevenot G, Cloez JL, Brembilla B, Pernot C. Doppler echocardiographic measurement of low velocity motion of the left ventricular posterior wall. Am J Cardiol. 1989 Jul 1;64(1):66-75.〕 and by the Autocorrelation technique as colour Tissue Doppler 〔McDicken WN, Sutherland GR, Moran CM, Gordon LN. Colour Doppler velocity imaging of the myocardium. Ultrasound Med Biol. 1992;18(6-7):651-4.〕 (Duplex ultrasonography). While pulsed Doppler only acquires the velocity at one point at a time, colour Doppler can acquire simultaneous pixel velocity values across the whole imaging field. Pulsed Doppler on the other hand, is more robust against noise, as peak values are measured on top of the spectrum, and are unaffected of the presence of clutter (stationary reverberation noise).
==Pulsed Tissue Doppler echocardiography==
This has become a major echocardiographic tool for assessment of both systolic and diastolic ventricular function. However, as this is a spectral technique, ''it is important to realise that measurement of peak values is dependent on the width of the spectrum, which again is a function of gain setting''.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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