title: Intravascular enhancement with identical iodine delivery rate using different iodine contrast media in a circulation phantom.
abstract: OBJECTIVE
  Both iodine delivery rate (IDR) and iodine concentration are decisive factors for vascular enhancement in computed tomographic angiography. It is unclear, however, whether the use of high-iodine concentration contrast media is beneficial to lower iodine concentrations when IDR is kept identical. This study evaluates the effect of using different iodine concentrations on intravascular attenuation in a circulation phantom while maintaining a constant IDR.
  
  
  METHODS
  A circulation phantom with a low-pressure venous compartment and a high-pressure arterial compartment simulating physiological circulation parameters was used (heart rate, 60 beats per minute; stroke volume, 60 mL; blood pressure, 120/80 mm Hg). Maintaining a constant IDR (2.0 g/s) and a constant total iodine load (20 g), prewarmed (37°C) contrast media with differing iodine concentrations (240-400 mg/mL) were injected into the phantom using a double-headed power injector. Serial computed tomographic scans at the level of the ascending aorta (AA), the descending aorta (DA), and the left main coronary artery (LM) were obtained. Total amount of contrast volume (milliliters), iodine delivery (grams of iodine), peak flow rate (milliliter per second), and intravascular pressure (pounds per square inch) were monitored using a dedicated data acquisition program. Attenuation values in the AA, the DA, and the LM were constantly measured (Hounsfield unit [HU]). In addition, time-enhancement curves, aortic peak enhancement, and time to peak were determined.
  
  
  RESULTS
  All contrast injection protocols resulted in similar attenuation values: the AA (516 [11] to 531 [37] HU), the DA (514 [17] to 531 [32] HU), and the LM (490 [10] to 507 [17] HU). No significant differences were found between the AA, the DA, and the LM for either peak enhancement (all P > 0.05) or mean time to peak (AA, 19.4 [0.58] to 20.1 [1.05] seconds; DA, 21.1 [1.0] to 21.4 [1.15] seconds; LM, 19.8 [0.58] to 20.1 [1.05] seconds).
  
  
  CONCLUSIONS
  This phantom study demonstrates that constant injection parameters (IDR, overall iodine load) lead to robust enhancement patterns, regardless of the contrast material used. Higher iodine concentration itself does not lead to higher attenuation levels. These results may stimulate a shift in paradigm toward clinical usage of contrast media with lower iodine concentrations (eg, 240 mg iodine/mL) in individual tailored contrast protocols. The use of low-iodine concentration contrast media is desirable because of the lower viscosity and the resulting lower injection pressure.
authors.affiliation: From the *Department of Radiology, †CARIM School for Cardiovascular Diseases, Maastricht University Medical Center, Maastricht, The Netherlands; ‡Health Informatics Research and Strategy, MEDRAD Radiology & Interventional, Bayer HealthCare, Indianola, PA; §Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands; Departments of ∥Neuroradiology, and ¶Nuclear Medicine, University Hospital RWTH Aachen, Aachen, Germany.
authors.forename: Casper
authors.initials: C
authors.lastname: Mihl
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Wildberger
authors.forename: Tomas
authors.initials: T
authors.lastname: Jurencak
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Yanniello
authors.forename: Estelle C
authors.initials: EC
authors.lastname: Nijssen
authors.forename: John F
authors.initials: JF
authors.lastname: Kalafut
authors.forename: Georgi
authors.initials: G
authors.lastname: Nalbantov
authors.forename: Georg
authors.initials: G
authors.lastname: Mühlenbruch
authors.forename: Florian F
authors.initials: FF
authors.lastname: Behrendt
authors.forename: Marco
authors.initials: M
authors.lastname: Das
mesh_terms: D000792:Angiography / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D007479:Iopamidol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; C057937:iomeprol; D007472:Iohexol; C038192:iopromide; D007479:Iopamidol