Computing method of blood flow volume and blood flow velocity of blood vessel per unit time

Abstract

The invention discloses a computing method of blood flow volume and blood flow velocity of a blood vessel per unit time. The computing method comprises the following steps: selecting an interesting region and computing and fitting out a fitting curve, that the grey level of the interesting region varies with time, in an image sequence, computing a time point that the grey level fitting curve achieves the highest descending (or ascending) speed, and integrating the grey level varying fitting curve within a preset time interval taking the time point as a center, so that an area value is obtained; and acquiring blood flow volume per unit time corresponding to the area value, and in combination with the lumen area of the blood vessel, further acquiring blood flow velocity. The computing method disclosed by the invention is innovative that the blood flow volume within an entire cardiac cycle time is computed by taking the position that that the grey level fitting curve achieves the highest descending (or ascending) speed as a center, so that the blood flow volume and blood flow velocity per unit time can be computed more accurately, and errors caused by computing in improper time intervals can be effectively avoided.

Description

technical field [0001] The invention relates to the application in the medical field, in particular to the accurate, rapid and non-invasive calculation of blood flow and blood flow velocity per unit time based on images. Background technique [0002] The stenosis of blood vessels caused by plaque affects the blood supply to the myocardium and poses a threat to human health. Coronary angiography can show the severity of coronary stenosis, but it cannot reflect the functional significance of the stenosis. Fractional flow reserve (FFR) is evaluated as the gold standard for diagnosing coronary artery function. The ratio of the pressure at the distal end of the stenotic lesion to the pressure at the proximal end of the stenosis was calculated. [0003] Invasive and invasive pressure measurement of blood vessels through pressure sensors is not only a lot of work, but also has the risk of damaging blood vessels. The geometric model of the coronary system can be obtained by three...

AI Technical Summary

Problems solved by technology

[0011] (1) The measurement accuracy of blood flow velocity is limited by the estimation of vessel length and shortening overlap phenomenon of coronary angiography

[0012] (2) It is necessary to manually determine the starting position (starting frame) of contrast agent entering the coronary artery and the ending position (ending frame) of filling to the distal end of the target, and the calculation accuracy is affected by human factors

[0013] (3) The calculation of the blood flow velocity should be measured before the contrast agent leaves the vessel segment of interest. The filling speed of the contrast agent is fast, and the time for passing through the vessel segment of interest only takes up a certain period of time in one heartbeat cycle (usually less than One cardiac cycle), which will lead to the blood flow velocity determined in different periods of the heartbeat cycle is usually the mean value of the blood flow velocity of the non-integer cardiac cycle, and there is a large deviation from the actual average blood flow velocity

[0014] (4) Select a large region of interest, such as the entire coronary artery and its downstream perfused myocardial microvessels, for calculation, and it is impossible to ensure that the image grayscale change curve corresponding to the process of contrast agent filling the region of interest falls or rises. It is an integer number of cardiac cycles, which will lead to a large deviation between the calculated blood flow per unit time or the average blood flow velocity and the actual blood flow per unit time or average blood flow velocity

[0015] (5) The direct measurement of blood flow velocity is invasive, and the Doppler blood flow guide wire instrument is expensive and difficult for patients to bear, which limits the clinical application of this method

[0016] (6) The contrast region of interest will not shift correspondingly with the movement of the target blood vessel in the contrast sequence, resulting in the change of gray value in the region of interest not only due to the transmission of contrast agent in the target blood vessel, but also due to the change of the target blood vessel. Migration and side branch vessel migration lead to inaccurate calculation of blood flow or blood flow velocity per unit time

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