| 摘要 |
A matched filtering method for X-ray image subtraction procedures in which an X-ray contrast medium is injected intravenously. A sequence of pre-contrast X-ray images are made during a period before the medium arrives in a blood vessel that is to be imaged and the sequence is continued through the post-contrast period and in some cases, an after-contrast period. A curve or plot of how projected intensity of the contrast medium varies as a function, h, at times (t) is determined at some prior time based on characteristic patients or, in the alternative, by using the post-contrast image data obtained from the patient presently undergoing examination. In either case a sequence of coefficients or weighting factors are produced that are proportioned to the value of the function h at the time (t) at which the corresponding image in the post-contrast sequence was acquired. By multiplying the coefficients and their time matched images, those images which have more contrast medium intensity get the most weight, which taken in conjunction with some image subtraction steps, results in maximizing contrast medium signal relative to noise and in utilizing all of the contrast medium signal. |
