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Rationale and Objectives: Enhancement characteristics of a nonionic, dimeric, isotonic contrast medium (iodixanol [Visipaque]) were compared with a nonionic, monomeric contrast medium (ioversol [Optiray]) of the same iodine concentration in spiral computed tomography angiography (CTA) of the abdominal aorta., Methods: Spiral CTA was performed in 78 patients referred for suspected renal artery stenosis (n = 35) and abdominal aortic aneurysm (n = 43). A test bolus was used to time the scan delay, and all patients were injected with 150 ml contrast medium (320 mgI/ml) of either iodixanol (n = 40) or ioversol (n = 38). Contrast enhancement was measured in the aorta, renal arteries, and renal parenchyma., Results: All mean aortic enhancement was slightly higher with iodixanol than ioversol, measured at three different levels (celiac trunk 315 Hounsfield units [HU] versus 300 HU, renal arteries 325 HU versus 312 HU, aortic bifurcation 276 HU versus 266 HU). However, none of them were statistically significant (e.g., P = 0.26 at the celiac trunk level). Similar results were observed in renal artery and parenchyma enhancements., Conclusions: Iodixanol and ioversol had similar enhancement characteristics in the early arterial phase. Both substances were well tolerated and seem to be well suited for spiral CTA.

The interference of the non-ionic magnetic resonance contrast medium gadodiamide injection (OMNISCAN, Nycomed Imaging, Oslo, Norway) in the colorimetric determination of serum calcium has been investigated in commercial reconstituted serum, and in serum from rabbits and humans dosed with the contrast medium. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and ion-selective electrodes were used as reference methods for analysis of serum calcium. The results showed that the colorimetric reagent kit gave an apparent decrease in serum calcium after administration of a clinical dose of gadodiamide injection, and that the extent of interference is correlated to the concentration of the contrast medium. However, serum calcium was not changed when measured by means of an ion-selective electrode or ICP-AES. It is therefore recommended that colorimetric reagent kits should not be used for determination of serum calcium in samples taken within the first 24 h after administration of gadodiamide injection.

Gadodiamide injection (Gd-DTPA-BMA) is a new non-ionic paramagnetic contrast agent for which the safety at the dose 0.1 mmol/kg was evaluated during a European multicentre study on a large population of adult patients who had an MR examination of the central nervous system with contrast medium. The safety analysis was performed on 2,102 patients by recording the adverse events observed during injection and up to 24 hours after the injection. Adverse events due or probably due to gadodiamide injection were observed in 102 patients (4.4%) with injection-site associated discomfort (heat, coldness, pain at the injection site) in 37 patients (1.8%) and adverse events other than discomfort (headache, nausea, vomiting) in 35 patients (3.1%). No adverse events of severe intensity or death were reported during the trial. Gadodiamide injection was shown to be safe and well tolerated and represents a non-ionic alternative to the current products in the field of MR imaging of the central nervous system.

The dialyzability of iohexol was examined in patients with chronic renal failure on long-term hemodialysis treatment. Eight patients had iohexol (Omnipaque 240 or 350 mg I/ml) injected in doses between 98 and 1,493 mg I/kg body weight (BW) 25 h (mean time) before start of hemodialysis. Dialysance of iohexol was 81 +/- 15 ml/min (mean +/- SD) compared to 120 +/- 16.8 ml/min for creatinine. Elimination half-life for iohexol during hemodialysis was 3.9 +/- 1.1 h while plasma clearance was 64 +/- 17 ml/min. The distribution volume calculated (0.25 +/- 0.05 liters/kg BW) confirms previous observations with distribution in the extracellular fluid only. Before the start of hemodialysis 36 +/- 28% of the dose injected was eliminated, indicating some extrarenal elimination. After 4 h of hemodialysis 72 +/- 11% of the dose was removed.