Gadobutrol at different injection rates for dynamic supra-aortic imaging by contrast-enhanced magnetic resonance angiography

The aim of this study was to compare differences in imaging quality at different injection rates of gadobutrol (Gadovist® 1.0M ) for dynamic supra-aortic imaging by contrast-enhanced magnetic resonance angiography (CEM RA). In 6 healthy volunteers, dynamic CEM RA examinations were performed twice at a 7 d interval with a gadobutrol dose of 0.1 mmol given to 1 kg body mass. For the two examinations, the contrast medium was injected at rates of 1.5 mL/s and 2.0 mL/s, followed by 20 mL normal saline injected at the same rate. Using a GE Signa 3.0T M R apparatus and the time-resolved imaging of contrast kinetics (TRICKS) technique, scanning was performed continuously for 15 phases at a time resolution of about 2.4 s. Vascular reconstruction was undertaken by multiplane reconstruction and maximum intensity projection techniques. Two radiologists experienced in CEM RA diagnosis subjectively evaluated the contrast effect, vascular detail, and pseudo-shadow of all images, and graded them via a 5-point scale. With the two drug injection rates, the image quality, peak signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were compared for imaging of the infra-aortic arch, brachiocephalic trunk, subclavian artery (left/right), common carotid artery (left/right), internal carotid artery (left/right), and external carotid artery (left/right). Characteristics of the time-signal-intensity (T-S-I) curves were also analyzed at the two injection rates. All studies were performed successfully , without any complications. There was good image quality with both gadobutrol injection rates of 1.5 mL/s and 2.0 mL/s, and subjective scores for image quality, SNR and CNR were not significantly different between the two rates (P > 0.05). The time-to-peak (TTP) from the hand dorsal vein injection site to the carotid artery ranged from 16.0 s to 27.1 s (mean 21.7 s ±3.4 s) in the 6 subjects, and was also not significantly different between the two drug injection rates (P > 0.05). We conclude that dynamic CEM RA examination of the supra-aortic arch with gadobutrol injection at a rate of 1.5 mL/s was feasible, and satisfactorily reflected vascular shape and dynamic blood flow information.