In vitro evaluation of teratogenic effects by time-varying MR gradient fields on fetal human fibroblasts.

The purpose of this study was to evaluate the influence on fetal cell growth in vitro of rapidly changing magnetic gradient fields such as those produced by the gradient coils of a typical magnetic resonance (MR) imager. The static magnetic field and the radiofrequency pulses were disabled during all measurements. Human fetal fibroblasts were placed within a specially designed MR-compatible incubation system inside the magnet. Trapezoid-shaped waveforms of 500 and 75 Hz base frequency and an amplitude of 2 mT were applied for 2-24 hours. Proliferation of the cells was monitored for 3 weeks after exposure. Cell cycle analysis was performed until 24 hours after exposure to detect alterations in cell division. Tests were performed under two different conditions of growth to detect increased as well as decreased proliferation effects. None of these tests showed differences in proliferation and cell cycle distribution between exposed and nonexposed cells.

Human fetal lung fibroblasts: in vitro study of repetitive magnetic field exposure at 0.2, 1.0, and 1.5 T.

PURPOSE: To evaluate whether repetitive exposure to magnetic fields of 0.2, 1.0, and 1.5 T affect the growth of human fetal lung fibroblasts (HFLFs). MATERIALS AND METHODS: Cultured HFLFs were exposed to static magnetic fields of 0.2, 1.0, and 1.5 T for 1 h/d for 5 consecutive days. Control groups were kept under identical environmental conditions, apart from the magnetic field, during the experiments. Cell cycle analysis for synchronously and nonsynchronously growing cells was performed. Population doublings (PDs) were calculated. To rule out midterm effects, proliferation kinetics of the cells were analyzed for 21 days. RESULTS: Cell cycle analysis of synchronized and nonsynchronized cells did not reveal statistically significant differences between the exposed and control cells. The PDs did not indicate any growth modulation during exposure. Proliferation kinetics did not provide any hint of midterm growth modulation effects of repetitive magnetic field exposure. CONCLUSION: Repetitive magnetic field exposure does not exert any growth-modulating effect on overall cell growth and cell cycle distribution of cultured HFLFs. Midterm effects due to magnetic field exposure were not found.

[Stability of iodinated contrast media in UV-laser irradiation and toxicity of the photoproducts]. / Stabilität jodhaltiger Röntgenkontrastmittel unter UV-Laser-Bestrahlung und Toxizität der Photoprodukte.

PURPOSE: In XeCl-Excimer laser angioplasty, unintended and possibly harmful interaction of the UV-laser light and the contrast media may occur due to the high concentration of contrast medium proximal to the occlusion or subtotal stenosis. METHODS: One ml of three nonionic monomeric contrast agents (iopromide, iomeprol, iopamidol), one nonionic dimeric (jotrolane), and one ionic monomeric (amidotrizoate) X-ray contrast agent were irradiated with a XeCl excimer laser (lambda = 308 nm, pulse duration 120 ns, 50 Hz) using a 9 French multifiber catheter (12 sectors). Up to 20,000 pulses (106 J) were applied. Using high performance liquid chromatography the amount of liberated iodide as well as the fraction of unchanged contrast media were measured. Cytotoxicity of the photoproducts was tested in a colony formation assay of human skin fibroblasts. The contrast agents were irradiated with 2000 pulses/ml (5.3 mJ/pulse; 10.6 J) and then added to the cell cultures for a period of three hours in a concentration of 10%. RESULTS: Excimer laser irradiation induced iodide liberation of up to 3.3 mg iodide/ml. Up to 19% of the contrast agents changed their original molecular structure. Incubation of irradiated contrast agents resulted in a significantly decreased potential for colony formation (p values ranging from 0.0044 to 0.0102) with significantly higher toxicity of amidotrizoate and iomeprol in comparison to iopromide, iotrolan, and iopamidol. DISCUSSION: Due to the cytotoxic photoproducts and the high level of liberated iodide, it is recommended to flush the artery with physiological saline solution before applying a pulsed excimer laser in human arterial obstructions in order to reduce the contrast agent concentration at the site of irradiation.

[Manganese DPDP as a contrast medium for MR tomography of focal liver lesions. Tolerance and image quality in 20 patients]. / Mangan-DPDP als Kontrastmittel für die MR-Tomographie fokaler Leberläsionen. Verträglichkeit und Bildgebung bei 20 Patienten.

Twenty patients with focal liver lesions (18 metastases, 1 hepatocellular carcinoma, 1 cholangiocarcinoma) were given manganese DPDP as part of a multicentric phase II study of paramagnetic hepatobiliary MR contrast media. 5 mumol/kg manganese DPDP were injected into 10 patients in a concentration of 50 mumol/ml or 10 mumol/ml (3 ml/min). Blood pressure, pulse rate, ECG, respiratory rate, body temperature, blood and serum parameters and the patients' subjective feelings were recorded. MRI was performed with 1.5 T using T1- and T2-weighted sequences. 6 patients reported 8 side effects (flushing, feeling of warmth, metallic taste); 7 of these were produced by the 50 mumol concentration. Two hours after injection there was a significant reduction in alkaline phosphatase which was no longer present after 24 hours. On T1-weighted images manganese DPDP resulted in marked improvement in the contrast difference between the lesions and the liver parenchyma which resulted in a marked increase in the signal to noise ratio. Comparing the two concentrations, better results were obtained by the lower concentration. Extrahepatic uptake was found in the gallbladder, duodenum, pancreas, kidneys, gastric mucosa and myocardium. Manganese DPDP in a concentration of 10 mumol/ml and a dose of 5 mumol/kg is a well tolerated contrast medium which improves the demonstration of focal liver lesions in view of its distribution and uptake. The mechanisms for the transitory side effects require further studies.