Simple method to estimate cardiac output using first-pass data on RI angiography

In order to estimate cardiac output (CO) without using data at equilibrium state, a simple index (cardiac output index, COI) was developed from the first-pass data as a ratio of the integrated radioactivity on the right ventricle to the total injected radioactivity. COI was well correlated with CO calculated by the conventional Stewart-Hamilton method (r=0.894, p<0.01), and thus, CO could be readily estimated from COI. This index might be useful to estimate CO since it can be obtained even with the agents which distribute to organs. (author)