50 ml of Iomeprol 400 (Imeron 400, Bracco Imaging S.p.A., Milan, Italy) were injected using a power injector with an injection rate of 5 ml/s and followed by a saline chaser of 20 ml using the same flow rate.
Five seconds into the first phase of scanning, contrast agent (150 μL of diluted Hypaque 300, 200 mg of iodine per ml) was injected via a tail vein catheter at an injection rate of 2.0 ml/min with an infusion pump (New Era Pump Systems Inc) that was triggered by the CT scanner.
After nasojejunal tube placement under fluoroscopic guidance, 1500 ml of 0.5% methylcellulose solution (MCS) are administered via a roller pump at an injection rate of 100 120 ml/min to provide adequate and uniform small bowel distension.
At time point T0, CA1 (Magnograf®, Bayer Pharma AG, Berlin, Germany, administered at a dose of 0.2 mL/kg body weight, with an injection rate of 4 mL/s) is injected generating a maximal arterial enhancement of the liver at time point T1, followed by injection of CA2 at T2 (Iomeron 370, administered at a dose of 1 mL/kg body weight, with an injection rate of 4 mL/s).
After this dynamic acquisition and following an additional 80-ml bolus of the same low-osmolar non-ionic contrast agent at an injection rate of 3 ml/s and a 30-s delay, a routine, post-contrast, spiral CT of the thorax (120 kV; 130 mAs with care dose automated exposure control) was obtained by using 5-mm-thick sections with a contiguous reconstruction algorithm.
Adequacy of the intravenous access route was tested with a 20-ml saline bolus at an injection rate of 8 ml/s.
Parametric analysis of the results suggest that the design criteria for optimal stimulation of tight gas sands is: an injection rate of 100 bpm a gel loading of 50 pptg of linear HPG a proppant size of 20/40 mesh sand 14.
Finally, a bolus intravenous injection of 0.1 mmol/kg gadopentetate dimeglumine followed by a 20 ml saline flush at an injection rate of 2 ml/s was administered, and the sequence was repeated.
As contrast agent, we used 0.1 mmol /kg body weight of gadolinium-diethylene-triamine-pentaacetic acid (Gd-DTPA) (Magnevist, Schering, Berlin, Germany), which was injected by a pneumatically driven injection pump at an injection rate of 5 mL /s.
