Thoracic and abdominal MRA with gadofosveset: influence of injection rate on vessel signal and image quality.

The purpose of this study was to investigate the influence of different injection rates on the maximum signal intensity and the arterio-venous transit time of dynamic gadofosveset-enhanced first pass MR angiography (MRA). Twenty-one healthy male volunteers were examined with a time-resolved echo-shared MRA at 1.5 T. The volunteers were assigned into three groups using injection rates of either 1, 2 or 4 ml/s. The maximal signal enhancement and peak signal-to-noise ratio in the pulmonary trunk, the aortic arch, the abdominal aorta as well as both kidneys and lung parenchyma were analyzed. The arterio-venous transit time was determined. The time between maximal enhancement of the pulmonary trunk and the aortic arch was higher with the slow injection rate of 1 ml/s, while there were no differences in the time between maximal enhancement of the aortic arch and the abdominal aorta above or below the origin of the renal veins with all three injection rates. With the slow injection protocol of 1 ml/s a longer purely arterial phase of 10.5 s was achieved compared to 7.7 s with higher injection rates (p = 0.045). The time between maximal aortic signal intensity and maximal renal enhancement was equal for all injection protocols.