Effect of contrast dilution on contrast-enhanced MR angiography of the aorta and renal arteries

The aim of this study was to investigate the effect of gadolinium chelate d ilution on vascular enhancement in contrast-enhanced two-dimensional (2D) M R subtraction angiography of aorta and renal arteries. Twenty patients were prospectively included. 2D subtraction MR angiography consisted of success ive multisection breathhold GRE acquisitions of 16 s (2D FLASH, TRITE 72/4, flip angle 60 degrees) obtained in the coronal plane before and after intr avenous bolus administration of 0.1 mmol/kg BW gadolinium chelate. Patients underwent both diluted and undiluted gadolinium chelate administration in a random order. The data were studied both qualitatively and quantitatively on source and maximum intensity projection images. The length of renal art eries opacified was found not to differ significantly according to contrast dilution. The contrast enhancement percentage was not significantly modifi ed according to the dilution used, but the time to peak enhancement was obs erved to be longer with the diluted contrast. Qualitatively, the best MR im ages were those obtained when undiluted contrast was injected first (chi (2 ), P = 0.01). At a dosage of gadolinium chelate 0.1 mmol/kg BW, undiluted c ontrast 2D MR subtraction angiography seems to be more appropriate for stud ying diseases of the aorta and renal arteries than a similar diluted dose.