Optimizing contrast-enhanced abdominal CT in infants and children using bolus tracking

OBJECTIVE, Manual administration of IV contrast material results in unpredi ctable injection rates. Our purpose was to determine the effect of bolus tr acking on overall abdominal helical CT scan quality, particularly on hepati c enhancement, in children with manually administered contrast media. MATERIALS AND METHODS. We compared 33 abdominal helical CT scans of 29 chil dren in whom bolus tracking was used with 22 CT scans of a control group of 21 children in whom bolus tracking was not used. All contrast material was administered by manual injection. Qualitative assessment was made of organ and vessel enhancement and overall scan appearance. Quantitative assessmen t using region-of-interest cursors was performed at three anatomic levels, and the results for the two groups of children were compared. RESULTS. Qualitative comparison of enhancement parameters between the bolus tracking group (number given first) and the control group (number given se cond) yielded the following: splenic artifact in 9% versus 23% (p = .24); i nferior vena cava flow artifact in 3% versus 27% (p = .01); scanning during the nephrographic phase in 89% versus 59% (p = .02); and good quality grad e in 79% versus 64% (p = .23). Significantly greater hepatic enhancement (a s measured in mean Hounsfield units) was achieved in the bolus tracking gro up than in the control group at the superior (48.5 versus 28.6; p < .001), middle (47.9 versus 32.3; p < .001), and inferior (48.2 versus 36.5; p = .0 1) levels. Hepatic enhancement increased significantly from the superior to the inferior level in the control group (p < .02), whereas enhancement was homogeneous in the bolus tracking group (p > .50). CONCLUSION. Bolus tracking provides improved contrast enhancement, includin g significantly greater hepatic enhancement, during abdominal helical CT in children in whom the rate of injection of contrast material is unpredictab le.