FIGURE 1. (A) Diagram of Rutland equation. Mo(t)/B(t) and B(t)dt/B(t) for each scan time (t) can be calculated from dynamic SPECT data. By plotting Mo(t)/B(t) against B(t)dt/B(t), the linear portion can be identified on curve. Presence of linear portion indicates that there is no significant excretion of BMIPP from myocardium during this period. (B) Determination of duration of linear portion in Rutland equation. Linear correlation coefficients from start of second scan (30 s) to specific scans were calculated and compared. For example, linear correlation coefficient (r) values are 0.9984 and 0.9836 up to 5 and 6 scans, respectively, in this case. Both values are considered to be sufficiently high to indicate a straight line. However, correlation coefficient up to 7 scans rapidly falls to 0.9427. Thus, we determined duration of linear portion to be up to 6 scans in this case. Slope (K value) can then be calculated.