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Hepatic spiral CT: reduction of dose of intravenous contrast material
J A Brink1, J P Heiken, H P Forman
1Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO 63110, USA.
Purpose:
To assess the potential for reduction of contrast material dose in hepatic spiral computed tomography (CT).
Materials And Methods:
Four hundred eighty-seven outpatients were randomized prospectively into nine biphasic and eight uniphasic injection protocols: 75, 100, or 125 mL of 240, 300, or 350 mg of iodine per milliliter of iohexol (18-44 grams of iodine). Protocols were compared according to the maximum hepatic enhancement (MAX) and the contrast enhancement index (CEI).
Results:
Uniphasic injection was superior to biphasic injection for all protocols. No statistically significant difference in contrast enhancement was present for 38-44 grams of iodine with the uniphasic technique. Adequate enhancement thresholds (MAX > 50 HU, CEI at 30 HU > 300 HU x sec) were exceeded in more than 70% of heavy patients ( > 183 lb [83 kg]) with uniphasic injection of 38 g. For thin patients ( < 183 lb [83 kg]), uniphasic injection of 26 g produced adequate enhancement.
Conclusion:
Contrast material dose may be reduced by up to 40% in thin patients undergoing hepatic spiral CT after uniphasic injection of contrast material; this may result in substantial cost savings.