Einfluß von Viskosität, Kanülengröße und Temperatur bei der maschinellen Kontrastmittelapplikation in der Computer- und Magnetresonanztomographie

Purpose: Mechanical contrast media application is used to improve image quality and allow better quantitative assessment of the contrast media kinetics for CT as well as MRI. The pressure within the i.v. line system must be known to enable safe and quantitatively exact application. Material and methods: Experimental setup to analyse the inline pressure, the storage volume as well as the exactness of delivery within the i.v. line system was prepared. Representative contrast media Ultravist(R) 300, Ultravist (R) 370, Magnevist (R) and Comay(R) 60 as well as 0.9% NaCl were measured with ten different now rates from 0.1 ml/sec to 5.0 ml/sec using the six most common i.v. cannula sizes (22G-14G). Results: System pressures between 38-60 psi (maximum allowed system pressure=60 psi) are commonly obtained with standard sizes of i.v. cannulas, such as an 18 G-cannula and flow rates greater than or equal to 2.5 ml/sec using Ultravist (R) 300 (viscosity 13 mPa . s at 20 degrees C). Higher system pressures (>25 psi) produce an exponential increase of the storage volume within the i.v. line system. The additional storage volume within the i.v. line tubing (d = 2.9 mm, 76 shore) is at 60 psi and 20 degrees C 5 ml/m, and at 37 degrees C 11 ml/m in addition to the volume of the tubing of 7 ml/m. Conclusion: Based on the measured data, both the minimum and the recommended sizes of the i.v. cannulas in respect of flow rate and viscosity of the used contrast media were compiled for system pressures at less than or equal to 60 psi as well as less than or equal to 38 psi.