Using a Saline Chaser to Decrease Contrast Media in Abdominal CT

Using a Saline Chaser to Decrease Contrast Media in Abdominal CT

Paul J. Dorio¹, Fred T. Lee, Jr., Kevin P. Henseler, Mark Pilot, Myron A. Pozniak, Thomas C. Winter, III and Sarah A. Shock

^¹ All authors: Department of Radiology, University of Wisconsin Hospital & Clinics, 600 Highland Ave., Madison, WI 53792-3252.

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Fig. 1. —46-year-old man with lung cancer. CT scan shows contrast material pooling in central veins after injection of 150 mL of contrast material. Residual contrast material also remains in left brachiocephalic vein (arrow). This contrast material is functionally wasted for purposes of enhancing abdominal organs and vasculature.

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Fig. 2. —Contrast material injector. Photograph shows initial position of power injector after loading both saline (s) and contrast material (c). Distinct layering effect occurs because of density differences between materials.

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Fig. 3. —Graph shows average lesion conspicuity (mean liver attenuation minus mean metastatic lesion attenuation) for each patient after injection of 100 mL of contrast material with 50 mL saline chaser ( ${blacksquare}$ ) and after injection of 150 mL of contrast material (•).

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Fig. 4A. —71-year-old man with neuroendocrine cancer. CT scan shows liver and tumor enhancement (metastases, arrows) after injection of 100 mL of contrast material and 50 mL of saline chaser. Mean liver attenuation = 84.7 H; mean tumor attenuation = 19.3 H; liver-to-lesion difference = 65.4 H.

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Fig. 4B. —71-year-old man with neuroendocrine cancer. CT scan shows liver and tumor enhancement (metastases, arrows) after injection of 150 mL of contrast material with injection parameters identical to those used for A. Mean liver attenuation = 89.8 H; mean tumor attenuation = 29.9 H; liver-to-lesion difference = 59.9. No difference in lesion conspicuity is seen compared with Figure 1A, despite slightly improved liver enhancement, because of simultaneous increase in tumor attenuation.

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Fig. 5A. —74-year-old woman with lung cancer. CT scan shows enhancement of spleen (155.8 H), renal cortex (188.1 H), and aorta (232.0 H) after injection of 150 mL of contrast material.

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Fig. 5B. —74-year-old woman with lung cancer. CT scan shows enhancement of spleen, renal cortex, and aorta after injection of 100 mL of contrast material and 50 mL of saline chaser with injection parameters identical to those used for A. Spleen (140.5 H), renal cortex (170.6 H), and aorta (187.8 H) are all slightly less enhanced compared with A. Decreased enhancement obtained with 100 mL of contrast material and chaser is generally not clinically important in patients with cancer, because metastases to spleen and kidney are relatively rare compared with hepatic metastases.

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