Usefulness of measurement of circulation time using MgSO4 : correlation with time-density curve using electron beam computed tomography

To determine the usefulness of MgSO4 for measuring the systemic circulation time. Systemic circulation time, defined as elapsed time from the injection of MgSO4 solution to the point of pharyngeal burning sensation, was measured in 63 volunteers. MgSO4 was injected into a superficial vein of an upper extremity. Using dynamic electron beam computed tomography at the level of the abdominal aorta and celiac axis, a time-intensity curve was plotted, and for these two locations, maximal enhancement time was compared. For 60 of the 63 subjects, both systemic circulation time and maximal enhancement time were determined. Average systemic circulation time was 17.4 (SD:3.6) secs. and average maximal enhancement times at the level of the abdominal aorta and celiac axis were 17.5 (SD:3.0) secs. and 18.5 (SD:3.2) secs., respectively. Correlation coefficients between systemic circulation time and maximal enhancement time for the abdominal aorta and celiac axis were 0.73 (p<0.01) and 0.73 (p<0.05) respectively. The systemic circulation time demonstrated by MgSO4 injection and maximal enhancement time for the abdominal aorta showed significant correlation. Thus, to determine the appropriate scanning time in contrast-enhanced radiological studies, MgSO4 can be used instead of a test bolus study