| 摘要 |
Blood flows through a blood vessel is monitored by angiography. A bolus of radio-opaque dye is injected by means of a motorised syringe (16) into the blood vessel over a period less than one cardiac cycle in response to the output of an ECG monitor (14). The dye bolus is injected at a predetermined point in the cardiac cycle. A sequence of X-ray images are then formed by X-ray apparatus (10) incorporating an image intensifier at predetermined intervals to provide an indication of movement of the bolus through the vessel and its branches. Preferably, the sequence of X-ray images are converted into digital format, the set of digital values representing each of the X-ray images being subtracted by means of computer (12) from those representing the next successive X-ray image in the sequence. Any negative digital values are converted to digital zeros. In order to provide an indication of volume flow through the blood vessel, the density of radio-opaque dye within a predetermined notional area at least a part of which overlies the area occupied by the blood vessel in the X-ray images is calculated for each set of digital values generated by the subtraction. The calculated densities can then be used to provide an indication of volume flow. <IMAGE> |
