Time‐resolved contrast‐enhanced three‐dimensional pulmonary MR‐angiography: 1.0 M gadobutrol vs. 0.5 M gadopentetate dimeglumine

Abstract

Purpose:To compare contrast characteristics and image quality of 1.0 M gadobutrol with 0.5 M Gd-DTPA for timeresolved three-dimensional pulmonary magnetic resonance angiography (MRA). Materials and Methods:Thirty-one patients and five healthy volunteers were examined with a contrast-enhanced time-resolved pulmonary MRA protocol (fast lowangle shot [FLASH] three-dimensional, TR/TE ϭ 2.2/1.0 msec, flip angle: 25°, scan time per three-dimensional data set ϭ 5.6 seconds). Patients were randomized to receive either 0.1 mmol/kg body weight (bw) or 0.2 mmol/kg bw gadobutrol, or 0.2 mmol/kg bw Gd-DTPA. Volunteers were examined three times, twice with 0.2 mmol/kg bw gadobutrol using two different flip angles and once with 0.2 mmol/kg bw Gd-DTPA. All contrast injections were performed at a rate of 5 mL/second. Image analysis included signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) measurements in lung arteries and veins, as well as a subjective analysis of image quality. Results:In patients, significantly higher SNR and CNR were observed with Gd-DTPA compared to both doses of gadobutrol ; P Յ 0.05). No relevant differences were observed between 0.1 mmol/kg bw and 0.2 mmol/kg bw gadobutrol. In volunteers, gadobutrol and Gd-DTPA achieved similar SNR and CNR. A significantly higher SNR and CNR was observed for gadobutrol-enhanced MRA with an increased flip angle of 40°. Image quality was rated equal for both contrast agents. Conclusion:No relevant advantages of 1.0 M gadobutrol over 0.5 M Gd-DTPA were observed for time-resolved pulmonary MRA in this study. Potential explanations are T2/ T2*-effects caused by the high intravascular concentration when using high injection rates. CONTRAST-ENHANCED three-dimensional pulmonary magnetic resonance angiography (MRA) has been proposed as a non-invasive and non-ionizing imaging modality for the evaluation of pulmonary vascular diseases (1-7). In addition to conventional monophasic protocols, time-resolved multiphasic pulmonary MRA has been proposed (6 -12). Depending on the temporal resolution and bolus timing, time-resolved pulmonary MRA typically provides different phases of contrastenhancement: a predominantly arterial phase, followed by a mixed arteriovenous phase, a predominantly venous phase, and a systemic arterial phase. One major advantage of time-resolved MRA over monophasic protocols is the improved arterial-venous discrimination of lung vessels (9 -12). Previous studies have shown that the quality of arterial-venous discrimination is influenced by the injection volume of contrast media, with a smaller injection volume producing a faster onset of peak enhancement and faster complete washout at no cost of maximum signal (10).Recently, new contrast agents offering an increased gadolinium concentration or a higher T1 relaxivity have been proposed for contrast-enhanced MRA (13-17). Due to the increased gadolinium concentration of 1.0 M gadobutrol, the injection volume can be halved compared to equimolar dosages of standard 0.5 M Gd-DTPA. The increased Gd concentr...

Contrast-enhanced magnetic resonance angiography (MRA): evaluation of three different contrast agents at two different doses (0.05 and 0.1 mmol/kg) in pigs at 1.5 Tesla

“…Contrary to these studies and to our results, previous studies on time- Fig. 4 Box-plots of SNR (bold line expresses the median, the box the 25% and 75% quartiles, circles the outliers) of the different contrast agents at the full dose and the half-dose Table 4 Overview of the measured signal-to-noise ratio CI confidence interval resolved MRA found no significant differences in the peak SNR when comparing gadobutrol and Gd-DTPA [16]. The authors of this study list several reasons for this result.…”

“…The authors of this study list several reasons for this result. Among them were the inherently lower signal of lung imaging and the higher viscosity of gadobutrol and the relatively smaller injection volumes of gadobutrol that might have influenced the bolus geometry of the contrast agent [16].…”

Dose optimization of contrast-enhanced carotid MR angiography

“…Previously, it was described that higher doses or contrast agent concentrations did not always improve CE-MRA diagnostics [26]. For the pulmonary vessels with doubleconcentration first-pass gadolinium-enhanced MRA, or for the supraaortic arch, where pseudo-stenoses were described, even penalties must be expected when exceeding certain limits.…”

Gadobutrol, a highly concentrated MR imaging contrast agent: its physicochemical characteristics and the basis for its use in contrast-enhanced MR angiography and in perfusion imaging

“…For central MR angiographies (e.g. pulmonary CE-MRA), the injection speed can be further increased up to 5 ml/s [17]. As discussed below in more detail, injection rates for Gadovist should be chosen carefully according to smaller volumes compared to 0.5 molar concentration.…”