Are Gadolinium-based Contrast Media Really Safer than Iodinated Media for Digital Subtraction Angiography in Patients with Azotemia?

Abstract

Are gadolinium-based contrast media really safer than iodinated media for digital subtraction angiography in patients with azotemia?

Gadolinium contrast media are more nephrotoxic than a low osmolar iodine medium employing doses with equal x-ray attenuation in renal arteriography: An experimental study in pigs1

“…In an ischemic rat model it was found that intra-aortic injections of gadopentetate and diatrizoate, both with an osmolality of about 2.0 osmol/kg water, caused a similar decrease in GFR measured as creatinine clearance. However, the dose of iodine atoms appeared to have been 10 times higher than that needed to achieve the same attenuation as the Gd-CM during an XRA study at 80 kV (21). Thus if equal-attenuating doses had been used it seems reasonable to assume that the nephrotoxic effect of diatrizoate had been much less.…”

“…The concentration at which I-CM are equal-attenuating with 0.5 M Gd-CM may vary with the x-ray tube kilovoltage (kV) used (30), which, in turn, may depend on patient size. We therefore used a concentration of a commonly used nonionic monomeric I-CM causing roughly the same attenuation of x-rays as an 0.5 M Gd-CM at the commonly used 70 -90 kV for XRA (ie, 0.18 M solution of iohexol [70 mg I/mL]) (21). We also used an 0.5 M iohexol solution (190 mg I/mL), which contains the same number of CM molecules as 0.5M Gd- CM, but three times the number of attenuating atoms.…”

“…The nephrotoxic effect of 2 Gd-CM, 0.5 M gadopentetate, and 0.5 M gadodiamide were compared with that of (1) an equimolar concentration of 0.5 M iohexol (190 mg I/mL), (2) 0.18M iohexol (70 mg I/mL), roughly equal-attenuating with 0.5M Gd-CM at about 80 kV (21), and (3) saline. Each pig was subjected to only one of the test solutions, which was injected in eight animals at a dose of 3 mL/kg and a rate of 20 mL/min.…”

“…The only reason for using I-CM or Gd-CM in XRA is to exploit their ability to attenuate x-rays. A recent review dealing with the toxicity of these agents and their ability to attenuate x-rays indicated that I-CM would probably show a lower renal toxicity than Gd-CM if compared in equal volumes in equal-attenuating concentrations (21). However, no such studies have been performed.…”

Gadolinium contrast media are more nephrotoxic than iodine media. The importance of osmolality in direct renal artery injections

“…There are no human studies comparing their nephrotoxic effects at volumes and concentrations resulting in the same x-ray attenuation [9,10]. The substitution of Gd-for I-CM appears contradictory not least in renal angiography/angioplasty procedures [1, 4,11], since osmotoxicity is an important factor in the pathophysiology of contrast medium induced nephropathy (CIN) [12,13] and direct injections of high-osmolal solutions, including CM, into the renal artery may be deleterious to the kidney [14][15][16][17].…”