Fig. 5

Plot of ΔR1 for the blood, myocardium, pleural effusion and pericardial effusion both early and late after contrast administration. Symbols denote the median, and whiskers the interquartile range. The red lines indicate change in ΔR1. ΔR1 is proportional to contrast agent concentration. Note how blood and myocardium have a relatively high contrast agent concentration early after contrast administration, which then decreases over time at the late time point. By comparison, both the pleural and pericardial effusions have measurable but low relative contrast agent concentrations early after contrast administration, which increase over time at the late time point, to a level that is lower than for blood and myocardium. These magnitudes and dynamics of relative contrast agent concentration suggest that the effusions do not establish a dynamic equilibrium with the blood. Thus, it would be misleading to calculate the extracellular volume fraction for the effusions