The authors evaluated the significance of different metal alloys used in orthopaedic surgery in producing artefacts during magnetic resonance imaging. Several MRI sequences were tested and magnetic effects evaluated. Twelve discs made of different metal alloys from three manufacturers were examined. These discs were placed in a plastic box with a defined position in ultrasound gel. Then a sensitive, standard T1 weighted gradient echo sequence (TE: 4.1 ms; TR 9.4) was carried out in a coronal plane (Matrix 128/256). A Phillips Easy Vision workstation was used for image analysis. The largest area of artefact formation, including the surface size of the disc, was calculated using a special software program. In order to minimise the measurement error all discs were measured 10 times and the average value was determined. Then eight different sequences were run and measured in the same way. In a second series, all discs were placed separately on metric paper and subjected to the magnetic field of the MRI in order to detect possible motion secondary to the magnetic field applied. The different titanium alloys showed average distortion areas of from 245 mm2 (Ti6Al4V) to 349 mm2 (Ti5Al2.5Fe). Cobalt chrome alloys yielded differences of between 600 mm2 and 651 mm2 and iron alloys of between 902 mm2 (316L or Fe18Cr10NiMo) and 950 mm2 (Fe22Cr10Ni4Mn2MoNb) on average for the standard T1 weighted gradient echo. The artefact areas were dependent on the different sequences performed. For steel, (Fe18Cr10NiMo) areas of from 411 mm2 (T1TSE) to 2027 mm2 (EPI/3D/SPIR) were measured. All sequences studied produced different artefact pictures. None of the materials tested showed changes in position secondary to ferromagnetism. The size of signal distortion by MRI depends on the alloy making up the implanted material and the sequences used. The smallest artefacts occurred with the turbo-spin-echo sequences (TSE). The alloys tested in our study seem to carry no risk for patients of ferromagnetically induced secondary loosening caused by MRI scanning.

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The higher 10mg dose of THC was dose-limiting in patients with ALS. High interindividual PK variability requires individuell titration of THC for potential therapeutic use in patients with ALS.

In the livers of pregnant rats an anabolic effect was found for zinc which, however, developed analogously to the enlargement of the organ. Femur and muscle did not reveal any super-retention of zinc during pregnancy. In the whole organism, a 10% increased zinc storage was found being attributable to stronger accumulation in the reproductive organs (3%) and in the liver (1%) and in other organs (6%) that were not under study. Higher Zn supply did not allow to increase this additional zinc storage during pregnancy. After lactation, the anabolic effect in the livers had declined, the Zn values of the lactating rats remaining, on the whole, at the same level as those of the pregnant animals. The Zn-serum concentrations as well as the alkaline phosphatase and carboxy peptidase A activities of the pancreatic gland were reduced during pregnancy, whilst the alkaline phosphatase activity in the femur increased. This finding is discussed in relation to Zn-supply and Zn-mobilisation.

Enhanced retention of nutrients in the gravid organism, which exceeds the normal deposition in the reproductive organs and in fetuses, is called ‘pregnancy anabolism’. For zinc this superretention could be established only in the liver which was enlarged in gravid rats, too. In all other tissues of gravid animals, zinc contents were lower compared with nongravid rats. After lactation, these changes in zinc status were equalized, and gravid and nongravid animals showed the same values.