Iodinated contrast media (CM) in computed tomographic angiography is characterized by its concentration and, consecutively, by its viscosity. Viscosity itself is directly influenced by temperature, which will furthermore affect injection pressure. Therefore, the purposes of this study were to systematically evaluate the viscosity of different CM at different temperatures and to assess their impact on injection pressure in a circulation phantom.
Initially, viscosity of different contrast media concentrations (240, 300, 370, and 400 mgI/mL) was measured at different temperatures (20°C–40°C) with a commercially available viscosimeter. In the next step, a circulation phantom with physical conditions was used. Contrast media were prepared at different temperatures (20°C, 30°C, 37°C) and injected through a standard 18-gauge needle. All other relevant parameters were kept constant (iodine delivery rate, 1.9 g I/s; total amount of iodine, 15 g I). Peak flow rate (in milliliter per second) and injection pressure (psi) were monitored. Differences in significance were tested using the Kruskal-Wallis test (Statistical Package for the Social Sciences).
Viscosities for iodinated CM of 240, 300, 370, and 400 mg I/mL at 20°C were 5.1, 9.1, 21.2, and 28.8 mPa.s, respectively, whereas, at 40°C, these were substantially lower (2.8, 4.4, 8.7, and 11.2 mPa.s). In the circulation phantom, mean (SD) peak pressures for CM of 240 mg I/mL at 20°C, 30°C, and 37°C were 107 (1.5), 95 (0.6), and 92 (2.1) psi; for CM of 300 mg I/mL, 119 (1.5), 104 (0.6), and 100 (3.6) psi; for CM of 370 mg I/mL, 150 (0.6), 133 (4.4), and 120 (3.5) psi; and for CM of 400 mg I/mL, 169 (1.0), 140 (2.1), and 135 (2.9) psi, respectively, with all P values less than 0.05.
Low concentration, low viscosity, and high temperatures of CM are beneficial in terms of injection pressure. This should also be considered for individually tailored contrast protocols in daily routine scanning.
From the *Department of Radiology, †CARIM School for Cardiovascular Diseases, Departments of ‡Clinical Chemistry, and §Cardiology, Maastricht University Medical Center, Maastricht, The Netherlands; Departments of ∥Neuroradiology, and ¶Nuclear Medicine, University Hospital RWTH Aachen, Aachen, Germany.
Received for publication August 30, 2013; and accepted for publication, after revision, October 24, 2013.
Conflicts of interest and sources of funding: none declared.
Madeleine Kok, MD, and Casper Mihl, MD, contributed equally to this work.
Reprints: Marco Das, MD, PhD, Maastricht University Medical Center, P. Debyelaan 25, PO Box 5800, 6202 AZ Maastricht, The Netherlands. E-mail: firstname.lastname@example.org.