Arterial first pass gadolinium-CM dynamics as a function of several intravenous saline flush and Gd volumes

This study was performed to evaluate the dynamics of an arterial first pass gadolinium (Gd) contrast medium (CM bolus at the descending aorta (DAo), d epending on various saline flush and Gd volumes. Using an ultra-fast two-di mensional GE-sequence (Siemens Vision (R), 1.5-T), 200 sequential cross-sec tional images of the addressed vessel (1 slice/s) were obtained. Several sa line flush volumes (15 mL, 30 mL, and 60 mL) were applied following the adm inistration of 10 mL Gd (single dose) to a group of 4 normal volunteers (bo dy weight 50-55 kg) using a mechanical MR injector (injection rate = 3.0 mL /s). Additionally, when performing a second test series, the saline volume remained constant, while the Gd volumes were varied from half doses to trip le doses (5, 10, 20, and 30 mL Gd were given to every volunteer of the grou p). The signal intensity versus time (SI/T) curve at a measured region of i nterest (ROI) within the DAo was calculated. The bolus arrival time (BAT), the maximal signal-to-noise ratio (SNRmax) the bolus time length (BL; 75% a nd 80% maximum intensity duration), the slope of the SI/T curve, and the ar eas below the SI/T curve for both the 80% and 75% maximum intensity duratio n level (INT80%, and INT75%) were calculated. The increase of saline flush volume from 30 to 60 mL caused significant bolus lengthening of approximate ly 50% (mean BL = 9.5 s, 10.3 s, and 15.4 s for 15 mL, 30 mL, and 60 mL sal ine flush volumes, respectively, measured as SI/T duration at the 75% SNRma x level). Using saline flush volumes equal to or higher than 30 mL increase d the slope of the SI/T curve. A continuous increase of INT75%/80% by using higher saline flush volumes was found. Different saline and Gd volumes did not affect the SNRmax and the BAT. Only the low dose (0.05 mmol/kg Gd) sho wed a 17%-21.6% significantly lower SNRmax. The BL and the INT increased ma inly by enlarging of applied Gd volume from single to double dose (BL75% an d INT75% were 9.6 s and 1305, 12.3 s and 2121, 38.5 s and 6181, 37.8 s and 6613 for 5, 10, 20, and 30 ml, applied Gd volume, respectively). The arteri al bolus length benefits from increasing Gd and saline flush volumes due to increased venous bolus length and wash out effects of Gd within the Inject ion site of the vein. Doses larger than a single dose are not needed to inc rease the SNR in contrast-enhanced magnetic resonance angiography images of the thoracic aorta. (C) 2001 Wiley-Liss, Inc.