Hyun Woo Goo MD, Presenter: Nothing to Disclose

Dong Hyun Yang MD, Abstract Co-Author: Nothing to Disclose

To evaluate the effects of diluted contrast agent as a chaser in thoracic multi-detector row CT on artifacts and vascular enhancement.

Thirty-nine patients (median age 9 years, range 2 years–16 years), who performed two consecutive thoracic 16-detector row CT examinations prior to and after a change in injection method of iodinated contrast agent (300 mgI/ml), were enrolled in this study. With an old protocol, diluted contrast agent (1.2 ml/kg contrast agent + 0.6 ml/kg saline) was administered first and followed by saline chaser. With a new protocol, undiluted contrast agent (1.2 ml/kg) was followed by diluted contrast agent (1:25 or 3:100 normal saline dilution) instead of saline chaser. In all patients, Intravenous injection was done through an arm vein with a dual power injector, scan delay was determined by automatic bolus tracking system, and caudocranial scan direction was employed. Attenuation was measured in great thoracic vessels (superior vena cava, pulmonary artery, ascending aorta, and descending aorta). Perivenous artifacts from undilated contrast agent were graded by two radiologists on a four-point scale.

Attenuations of great thoracic vessels with the old injection protocol (superior vena cava, 586.8±277.6 HU; pulmonary artery, 338.2±101.7 HU; ascending aorta, 321.3±84.7 HU; descending aorta, 323.9±87.8 HU) were significantly higher than those with the new injection protocol (superior vena cava, 425.8±269.5 HU; pulmonary artery, 289.2±79.9 HU; ascending aorta, 280.4±49.7 HU; descending aorta, 281.9±50.1 HU) (p < 0.01). Perivenous artifacts with the old injection protocol (superior vena cava, 1.6±1.3; subclavian vein, 2.0±1.3) were significantly greater than those with the new injection protocol (superior vena cava, 0.8±1.1; subclavian vein, 1.4±1.2) (p < 0.05).

In thoracic multi-detector row CT, the use of diluted contrast agent as a chaser appears to reduce perivenous artifacts and provide adequate vascular enhancement.

The new injection protocol evaluated in this study may improve the image quality of contrast-enhanced thoracic multi-detector row CT.

Goo, H, Yang, D, Diluted Contrast Agent as a Chaser in Thoracic Multi-Detector Row CT: Effects on Artifacts and Vascular Enhancement.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5003305.html