NMR and MRI obtained with high transition temperature dc SQUIDs

Abstract

Usando um espectrômetro baseado em um SQUID (dispositivo supercondutor de interferência quântica), de alta temperatura de transição, polarizado continuamente, medimos sinais de ressonân-cia magnética nuclear (RMN) de várias amostras a temperatura ambiente em campos magnéticos na faixa entre 0,05 mT e 2 mT. É possível observar sinais de prótons em uma amostra com 1 mL de óleo mineral em 2 mT com apenas uma aquisição. A sensibilidade do sistema também permite a detecção de RMN de prótons em um campo magnético tão baixo quanto 0,059 mT, o qual é comparável ao campo da Terra. Estes resultados tornam possíveis vários outros experimentos em imagens por ressonância magnética nuclear. Apresentamos uma imagem em duas dimensões obtida a temperatura ambiente em um campo magnético de 2 mT a partir de um padrão com uma estrutura interna preenchida com óleo mineral.We have measured nuclear magnetic resonance (NMR) signals from several samples at room temperature in magnetic fields ranging from about 0.05 mT to 2 mT using a spectrometer based on a high-Tc dc SQUID (high transition temperature dc Superconducting QUantum Interference Device). We are able to observe proton signals from 1 mL of mineral oil in 2 mT in a single transient. The sensitivity of this system has also allowed the detection of proton NMR at magnetic fields as low as 0.059 mT, which is comparable to the Earth's field. Such results make possible a number of new experiments in magnetic resonance imaging (MRI). We present a two-dimensional image of a phantom filled with mineral oil obtained in a field of 2 mT.

Characterization of magnetic nanoparticles as contrast agents in magnetic resonance imaging using high-Tcsuperconducting quantum interference devices in microtesla magnetic fields

“…The feasibility of using SQUIDs in conjunction with NMR and MRI technologies has been actively studied [11][12][13][14][15][16][17][18]. A review of NMR was given in [19].…”

Advances in biomagnetic research using high-Tcsuperconducting quantum interference devices

“…This has been demonstrated in agarose gel and water [58]. For these reasons, a number of lowfield NMR systems employ SQUID sensors below 10 mT using high-T c or low-T c SQUIDs [59][60][61][62][63][64][65][66][67][68][69][70][71][72]. For a review of SQUIDbased NMRs, one may refer to [58,69,70].…”

Computational and Phantom-Based Feasibility Study of 3D dcNCI With Ultra-Low-Field MRI

“…The realization of ultra-low-field (ULF) magnetic resonance imaging (MRI), i.e., MRI in the µT-regime, was possible when new, very sensitive superconducting quantum interference devices (SQUID) sensors could be used to detect nuclear spin precession [1,2], and, within a few years, several ULF scanners have been developed [3][4][5][6][7]. As the magnetization of the examined volume scales with the surrounding magnetic field, ULF MRI has to cope with a lower signalto-noise ratio (SNR) compared to high-field MRI-typically employing fields on the order of 1 T and above.…”