This work provides a systematic comparison of the signal-to-noise ratio (SNR), spatial resolution, acquisition time and metabolite limits-of-detection for magnetic resonance microscopy and... Show moreThis work provides a systematic comparison of the signal-to-noise ratio (SNR), spatial resolution, acquisition time and metabolite limits-of-detection for magnetic resonance microscopy and spectroscopy at three different magnetic field strengths of 14.1 T, 17.6 T and 22.3 T (the highest currently available for imaging), utilizing commercially available hardware. We find an SNR increase of a factor 5.9 going from 14.1 T to 22.3 T using 5 mm radiofrequency (saddle and birdcage) coils, which results in a 24-fold acceleration in acquisition time and deviates from the theoretically expected increase of factor 2.2 due to differences in hardware. This underlines the importance of not only the magnetic field strengths but also hardware optimization. In addition, using a home-built 1.5 mm solenoid coil, we can achieve an isotropic resolution of (5.5 mu m)(3) over a field-of-view of 1.58 mm x 1.05 mm x 1.05 mm with an SNR of 12:1 using 44 signal averages in 58 h 34 min acquisition time at 22.3 T. In light of these results, we discuss future perspectives for ultra-high field Magnetic Resonance Microscopy and Spectroscopy. (C) 2020 The Authors. Published by Elsevier Inc. Show less
Hubert, J.; Neo, Y.Y.; Winter, H.V.; Slabbekoorn, H. 2019
Anthropogenic sources increasingly contribute to the underwater soundscape and this may negatively impact aquatic life, including fish. Anthropogenic sound may mask relevant sound, alter behaviour,... Show moreAnthropogenic sources increasingly contribute to the underwater soundscape and this may negatively impact aquatic life, including fish. Anthropogenic sound may mask relevant sound, alter behaviour, physiology, and may lead to physical injury. Behavioural effect studies are often seen as critical to evaluate individual and population-level impact. However, behavioural responsiveness likely depends on context and characteristics of sound stimuli. We pose that ambient sound levels, signal-to-noise ratio (SNR), and pulse rate interval (PRI), could affect the behavioural response of fish. To study this, we experimentally exposed groups of tagged European seabass (Dicentrarchus labrax) to different impulsive sound treatments that varied in pulse level, elevated background level, SNR, and PRI. Upon sound exposure, the seabass increased their swimming depth. The variation in the increase in swimming depth could not be attributed to pulse level, background level, SNR or PRI. It may be that the current range of sound levels or PRIs was too narrow to find such effects. Show less
Hoogstins, C.; Burggraaf, J.J.; Koller, M.; Handgraaf, H.; Boogerd, L.; Dam, G. van; ... ; Burggraaf, J. 2019
