Animal study assessing safety of an acoustic coupling fluid that holds the potential to avoid surgically induced artifacts in 3D ultrasound guided operations

BACKGROUND: Use of ultrasound in brain tumor surgery is common. The difference in attenuation between brain and isotonic saline may cause artifacts that degrade the ultrasound images, potentially affecting resection grades and safety. Our research group has developed an acoustic coupling fluid that attenuates ultrasound energy like the normal brain. We aimed to test in animals if the newly developed acoustic coupling fluid may have harmful effects. METHODS: Eight rats were included for intraparenchymal injection into the brain, and if no adverse reactions were detected, 6 pigs were to be included with injection of the coupling fluid into the subarachnoid space. Animal behavior, EEG registrations, histopathology and immunohistochemistry were used in assessment. RESULTS: In total, 14 animals were included, 8 rats and 6 pigs. We did not detect any clinical adverse effects, seizure activity on EEG or histopathological signs of tissue damage. CONCLUSION: The novel acoustic coupling fluid intended for brain tumor surgery appears safe in rats and pigs under the tested circumstances

Trace element composition and cathodoluminescence of kyanite and its petrogenetic implications

Kyanite crystals from fourteen localities worldwide were analysed for their abundances of the trace elements Na, Mg, K, Ca, Ti, V, Cr, Mn, and Fe and cathodoluminescence (CL) properties. Based on protolith type, metamorphic setting, and distinctive trace element fingerprints, a genetic classification of kyanite-bearing rocks is suggested: (A) Al-rich metasediments which commonly contain coarse-grained quartz-kyanite segregations; (B) metamorphosed granitic rocks, specifically granulites; (C) metamorphosed argillic alteration zones hosted originally in felsic igneous rocks; (D) metamorphosed argillic alteration zones hosted originally in mafic igneous rocks; and (E) metamorphosed mafic to ultramafic rocks, specifically eclogites. Vanadium and Cr concentrations reflect both protolith and host rock compositions and therefore may provide a geochemical fingerprint for the nature of the protolith. The incorporation of Fe into kyanite is largely controlled by oxygen fugacity during kyanite formation, and therefore, in most cases, its concentration cannot be related to that of the protolith. From our results, Ti concentration appears to be related to metamorphic grade, particularly formation temperature. If proven by further studies, Ti-in-kyanite may provide a useful geothermometer. Correlation of trace element abundances with CL spectra confirms that common red CL, which is composed of the spectral bands centred at 1.69 eV (734 nm), 1.75 eV (708 nm), and 1.80 eV (689 nm), is related to Cr3+ defects. CL spectra of most kyanites show in addition a low-intensity blue emission centred at 2.56 eV (485 nm). Correlation of the intensity of the blue emission with Ti suggests that it is related to or sensitized by Ti4+ or Ti3+ defects. Kyanites with >3200 mu gg(-1) Fe show generally no detectable CL due to the CL-quenching effect of Fe2+. Our findings provide new criteria in the exploration for and quality assessment of new kyanite deposits. The Ti content, one of the critical contaminants of kyanite products, besides Fe, Ca, and Mg, appears predictable from the observed correlation of Ti with formation temperature. Iron will be hard to predict because its incorporation is mainly controlled by the oxidizing conditions during kyanite formation and the estimation of these conditions requires advanced analytical methods. Magnesium and Ca are consistently low in all investigated samples. From a regional exploration viewpoint, group C and D kyanites have the lowest Ti and relative low Fe and, therefore, will be most refractory. Due to their attractive blue colour, kyanite-bearing rocks of group C have potential as ornamental or dimension stone.Geological Survey of Norway in Trondhei