[Administration of MR contrast agents outside of approved indications (off-label use]. / Einsatz von MR-Kontrastmitteln ausserhalb der zugelassenen Anwendung (Off-label use).

PURPOSE: The use of MRI contrast agents outside their labeled indications is routine in radiology. However, physicians feel frequently at unease. It is the aim of this paper to introduce the medical, juridicial and billing relevant issues in order to improve the knowledge on this topic. METHODS: The basis for off-label use is the physician's prerogative, which finds its basis in the "declaration of Helsinki". RESULTS: Off-label use is allowed under special conditions and might be even the medical state of the art. CONCLUSION: The necessity for off-label use will continue to increase for MR-contrast agents, as clinical trials for registration purpose are quite costly and manufactures continuously will concentrate on the essential indications.

[A comparison between GE and SE sequences in MRT after the i.v. application of superparamagnetic iron particles in the assessment of experimentally induced soft-tissue osteosarcomas]. / Vergleich zwischen GE- und SE-Sequenzen in der MRT nach i.v. Applikation von superparamagnetischen Eisenpartikeln bei der Beurteilung von experimentell induzierten Osteosarkomen der Weichteile.

PURPOSE: An MRI study on experimentally induced osteosarcomas of the peripheral soft-tissues in nude rats was conducted, comparing SE and GE sequences after i.v. application of superparamagnetic iron oxides with regard to contrast and image quality. MATERIAL AND METHODS: 40 nude rats with an osteosarcoma in the right hind leg and 7 tumour-free animals were measured without, one and 48 hours after i.v.-injection of the contrast medium. 4 SE and 3 GE sequences with different parameters and slice orientation were applied. The contrast medium consisted of Fe3O4 particles with a core diameter of 6-8 nm and a coating material of polyethylene glycol (PEG). The laboratory animals were divided into 5 groups of 7-12 animals each. The rats of the first 4 groups were given a contrast-medium dosage of 100, 150, 200 and 250 mumol Fe/kg body weight, respectively. The animals of the fifth group were tumour-free and served as controls. RESULTS: The minimum dosage for detection of Fe3O4-containing PEG magnetites, one hour after application, was established at 100-150 mumol Fe/kg body weight. The higher the dosage of the contrast medium, the more signal alterations could be measured. The GE sequences were more sensitive than SE sequences. One GE sequence with the parameters TR 90 ms, TE 13 ms, FL 8 degrees turned out to be highly sensitive. CONCLUSION: Superparamagnetic iron oxides induce signal alterations in tumours of the peripheral soft tissue. GE sequences proved to be more sensitive than SE sequences.