| 摘要 |
<p>PURPOSE:To obtain a picture without distortion while phase distortion is corrected once by obtaining the difference of two pictures obtained by a pulse sequence to change a flow encoding grade, obtaining a phase image to show the phase difference, operating and obtaining the residual phase distortion from the phase image and adding and subtracting so as to remove it. CONSTITUTION:Setting is executed so as to scan to an operation console with an ordinary pulse sequence and so as to scan with the pulse sequence to add a flow encoding grade 16. The picture obtained by an echo signal includes a phase distortion 21 due to a blood vessel 20 and a flow encoding grade. The average value of the phase on a segment a-a' in a Y axis direction may be obtained and the phase on the segment may be corrected in order to remove the phase distortion 21. In sections b-b', the blood vessel is finer that the position of the periphery generally, when the average value of the sections b-b' is obtained, the phase change part of the blood vessel 20 can be neglected by the average value, and by reducing the average value, the whole phase distortion is excluded. A computer receives an echo signal, obtains the residual phase distortion in an (x) axis direction, subtracts from the data of two pictures, adds and subtracts two original pictures again, removes the phase distortion due to the flow encoding grade and re-constitutes the picture.</p> |
