Velocity ultrasound tomography

Measurement of the 3-dimensional geometry is achieved by ultrasound velocity tomography (Mol, 1981 Mol et al, 1981), whereas measurement of intramural, endo- and epicardial deformations is performed by measuring distances between implanted radiopaque or natural (bifurcations of coronory arteries) markers with help of a biplane X-ray system (Elshuraydeh, 1981 Elshuraydeh et al., 1981). 

Interaction between ultrasound and tissue can be characterized by a number of parameters like speed of propagation, attenuation, absorption coefficients etc. As ultrasound velocity is characteristic for a particular tissue the possibility is opened for ultrasound velocity tomography. The principles hereof and implications for medicine have been described by Greenleaf et al. (1975). In ultrasound velocity tomography transmitters and receivers are positioned around the object under study. Times of flight of ultrasonic pulses from transmitter to receiver are measured accurately. By rotating the transmitters and receivers in a plane around... 

With ultrasound velocity tomography the local speed of ultrasound in a cross section of the subject under study is computed from a large set of ultrasound transmission times. These calculations (reconstructions) are based upon a model that describes the propagation of ultrasound in a medium. In its simplest form the ultrasonic pulses are supposed to travel along straight pathways from transmitter to receiver. The measured transmission times depends on the velocity distribution v(jc, y) in the plane of reconstruction ... 

In our model we aim to incorporate the interrelationship between cardiac muscle mechanics and coronary blood perfusion. In this model geometry of the heart plays an essential role. The method of ultrasound velocity tomography can be useful, as is demonstrated to measure the three-dimensional geometry of the heart in the laboratory with sufficient accuracy. The accuracy (the spatial resolution) of the tomogram depends on the total number of measurements. As the set of equations (lb) can be solved only if the number of variables does not exceed the... 

In Ultrasound computed tomography, the interaction between ultrasound wave and the body is used to determine the distribution of sound velocity c and the tissue density p. Ultrasound signals are stimulated and received by piezoelectric transducers. Received data is also processed by above mentioned algorithms, i.e by applying Fourier transform algorithm in order to reconstruct internal stmctures of the body as indicated in the following diagram ... 

Ultrasound tomography (UST), 205 Ultrasound transducer arrangement, 14 Urea-formaldehyde microcapsules, 67 UVP-DUO systems, 2, 7, 12-13 UVP measurements. See Ultrasonic velocity profiler (UVP) measurements... 

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