Three-dimensional contrast-enhanced magnetic-resonance angiography of the renal arteries: Interindividual comparison of 0.2 mmol/kg gadobutrol at 1.5 T and 0.1 mmol/kg gadobenate dimeglumine at 3.0 T

The purpose was to evaluate the image quality of high-spatial resolution MRA of the renal arteries at 1.5 T after contrast-agent injection of 0.2 mmol/kg body weight (BW) in an interindividual comparison to 3.0 T after contrast-agent injection of 0.1 mmol/kg BW contrast agent (CA). After IRB approval and informed consent, 40 consecutive patients (25 men, 15 women; mean age 53.9 years) underwent MRA of the renal arteries either at a 1.5-T MR system with 0.2 mmol/kg BW gadobutrol or at a 3.0-T MR scanner with 0.1 mmol/kg BW gadobenate dimeglumine used as CA in a randomized order. A constant volume of 15 ml of these contrast agents was applied. The spatial resolution of the MRA sequences was 1.0 × 0.8 × 1.0 mm3 at 1.5 T and 0.9 × 0.8 × 0.9 mm3 at 3.0 T, which was achieved by using parallel imaging acceleration factors of 2 at 1.5 T and 3 at 3.0 T, respectively. Two radiologists blinded to the administered CA and the field strength assessed the image quality and the venous overlay for the aorta, the proximal and distal renal arteries independently on a four-point Likert-type scale. Phantom measurements were performed for a standardized comparison of SNR at 1.5 T and 3.0 T. There was no significant difference (p > 0.05) between the image quality at 3.0 T with 0.1 mmol/kg BW gadobenate dimeglumine compared to the exams at 1.5 T with 0.2 mmol/kg BW gadobutrol. The median scores were between 3 and 4 (good to excellent vessel visualization) for the aorta (3 at 1.5 T/4 at 3.0 T for reader 1 and 2). For the proximal renal arteries, median scores were 3 for the left and right renal artery at 1.5 T for both readers. At 3.0 T, median scores were 3 (left proximal renal artery) and 4 (right proximal renal artery) for reader 1 and 3 (left/right) for reader 2 at 3.0 T. For the distal renal arteries, median scores were between 2 and 3 at both field strengths (moderate and good) for both readers. The κ values for both field strengths were comparable and ranged between 0.571 (moderate) for the distal renal arteries and 0.905 (almost perfect) for the proximal renal arteries. In the phantom measurements, a 40% higher SNR was found for the measurements at 3 T with gadobenate dimeglumine. High-spatial resolution renal MRA at 3.0 T with 0.1 mmol/kg BW gadobenate dimeglumine yields at least equal image quality compared with renal MRA at 1.5 T with 0.2 mmol/kg BW gadobutrol.