In the last few years there has been a substantial increase in preooperative and imaging diagnostics with the modern advancement in oncological liver surgery and therapy of focal liver tumours. For this purpose in addition to standard methods like sonography, computer tomography and MRI there is also the new organ specific contrast enhanced MRI. The organ specific contrast allows improved diagnosis in terms of detection and localisation of liver lesions and also in terms of characterisation and diagnosis of the parenchyma.

Methods

The iron oxide group belongs to the liver specific MRI contrast media which specially has an effect on the T2 relaxation time. The super paramagnetic iron oxide (SPIO) AMI-25 (Endorem®) is presently available for clinical use. A further smaller SPIO - SHU-555 A (Resovist®) is awaiting approval for clinical use. It is composed of iron-oxide crystals (Resovist®)enveloped by dextran (Endorem®) likewise Carboxydextran with an mean diameter of 150 nm likewise 58 nm. With a half life time of 8-10 min about 80% of the injected iron oxide particles are absorbed by the reticuloendothelial system (RES) of the liver through the Kupfer cells and about 12% are absorbed the RES of Spleen. The negative contrast enhancement is specially prominent in the proton density and T2 weighted sequences. A discrete T1 effect can be seen due to increase in T1 relaxation time.
Endoderm is given in dose of 15 µmol Fe/kg body weight through a filter canula in an infusion over a duration of 30 minutes. The application in 100 ml of 5% Glucose is done in two phases (2ml/min. and 4ml/min). Resovist in given in two different doses depending on body weight. It can be given as a bolus undiluted through a filter canula which allows dynamic studies of tumour vascularity and liver parenchyma.

 

Document Date: 2005/09/05   Author: unknown

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