Hybrid ultra‐low‐field MRI and magnetoencephalography system based on a commercial whole‐head neuromagnetometer

Vesanen, Panu T.; Nieminen, Jaakko O.; Zevenhoven, Koos C. J.; Dabek, Juhani; Parkkonen, Lauri; Zhdanov, Andrey; Luomahaara, Juho; Hassel, Juha; Penttilä, Jari; Simola, J.; Ahonen, Antti; Mäkelä, Jyrki P.; Ilmoniemi, Risto J.

doi:10.1002/mrm.24833

Cited by 20 publications

(36 citation statements)

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“…U ltrasensitive magnetic detection is utilized in a variety of applications, such as magnetoencephalography 1 , magnetocardiography 2 , ultra-low-field NMR 3 and magnetic resonance imaging (ULF NMR and MRI) [4][5][6] , exploration of magnetic minerals 7 and a wide range of other scientific purposes. The most established method is to use superconducting quantum interference devices (SQUIDs) based on low critical temperature superconducting materials 8,9 as the sensor, featuring field sensitivity in the fT Hz À 1/2 regime or below.…”

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confidence: 99%

Kinetic inductance magnetometer

et al. 2014

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Sensing ultra-low magnetic fields has various applications in the fields of science, medicine and industry. There is a growing need for a sensor that can be operated in ambient environments where magnetic shielding is limited or magnetic field manipulation is involved. To this end, here we demonstrate a new magnetometer with high sensitivity and wide dynamic range. The device is based on the current nonlinearity of superconducting material stemming from kinetic inductance. A further benefit of our approach is of extreme simplicity: the device is fabricated from a single layer of niobium nitride. Moreover, radio frequency multiplexing techniques can be applied, enabling the simultaneous readout of multiple sensors, for example, in biomagnetic measurements requiring data from large sensor arrays.

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Kinetic inductance magnetometer

et al. 2014

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“…In order to verify this method in a wider frequency range, we chose the 1D imaging frequencies at 1.3 kHz and 4.8 kHz, because the 1~2 kHz range is a typical frequency range of the hybrid MRI-MEG application [11,12], and 4.8 kHz is a common imaging frequency of ULF MRI. To evaluate the robustness of the adaptive suppression in the case of low SNR, we applied frequency encoding gradients in this experiment to make the signal amplitude comparable to those of the noise peaks.…”

Section: Effect Of Adaptive Suppression On 1d Mrimentioning

confidence: 99%

“…Hyperpolarization techniques, which significantly enhance spin population difference, were introduced in LF/ULF nuclear magnetic resonance (NMR) and MRI systems to obtain stronger SNR [5][6][7]. Some potential applications of ULF MRI have been demonstrated compared with high field MRI, e.g., enhanced contrast between cancerous and surrounding tissues [8,9], the possibility of imaging in the presence of metallic objects [10], the hybrid biomagnetic imaging of MRI and magnetoencephalography (MEG) [11,12] and the feasibility of neuronal current imaging [13][14][15]. Most of these advantages were achieved in a magnetically shielded room (MSR), which is costly, or in a shielded room made from aluminum a few millimeters thick.…”

Section: Introductionmentioning

confidence: 99%

Adaptive suppression of power line interference in ultra-low field magnetic resonance imaging in an unshielded environment

Huang

Dong

Qiu

et al. 2018

Journal of Magnetic Resonance

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Power-line harmonic interference and fixed-frequency noise peaks may cause stripeartifacts in ultra-low field (ULF) magnetic resonance imaging (MRI) in an unshielded environment and in a conductively shielded room. In this paper we describe an adaptive suppression method to eliminate these artifacts in MRI images. This technique utilizes spatial correlation of the interference from different positions, and is realized by subtracting the outputs of the reference channel(s) from those of the signal channel(s) using wavelet analysis and the least squares method. The adaptive suppression method is first implemented to remove the image artifacts in simulation. We then experimentally demonstrate the feasibility of this technique by adding three orthogonal superconducting quantum interference device (SQUID) magnetometers as reference channels to compensate the output of one 2 nd -order gradiometer. The experimental results show great improvement in the imaging quality in both 1D and 2D MRI images at two common imaging frequencies, 1.3 kHz and 4.8 kHz. At both frequencies, the effective compensation bandwidth is as high as 2 kHz. Furthermore, we examine the longitudinal relaxation times of the same sample before and after compensation, andshow that the MRI properties of the sample did not change after applying adaptive suppression. This technique can effectively increase the imaging bandwidth and be applied to ULF MRI in both an unshielded environment and a shielded room made from aluminum sheets.

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“…Such low-field NMR apparatuses, as compared to conventional high-field scanners, provide a higher frequency resolution of NMR lines [3,4], are less prone to susceptibility artefacts, require only moderate relative homogeneity of the static field [5] and, notably, the possibility of exploiting enhanced T1 contrast at low-field strengths, e.g., for the detection of tumours, has been recently suggested [6]. Finally, low-field NMR apparatuses can be integrated with other medical modalities such as magnetoencephalography (MEG) [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

NMR Detection at 8.9 Mt With a GMR Based Sensor Coupled to a Superconducting Nb Flux Transformer

Sinibaldi¹,

Luca²,

Nieminen³

et al. 2013

PIER

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Abstract-This study presents NMR signal detection by means of a superconducting channel consisting of a Nb surface detection coil inductively coupled to a YBCO mixed sensor. The NMR system operates at a low-field (8.9 mT) in a magnetically shielded room suitable for magnetoencephalographic (MEG) recordings. The main field is generated by a compact solenoid and the geometry of the pick-up coil has been optimized to provide high spatial sensitivity in the NMR field of view. The Nb detection coil is coupled to the mixed sensor through a Nb input coil. The mixed sensor consists of a superconducting YBCO loop with 2-µm constriction above which two Giant MagnetoResistance sensors are placed in a half-bridge configuration to detect changes of the bridge voltage as a function of the flux through the YBCO loop. The sensitivity of the receiving channel is calibrated experimentally. The measured spatial sensitivity is in agreement with the simulations and is ∼10 times better than that of the stand-alone mixed sensor. A NMR echo at 375 kHz shows a SNR only a factor 4 smaller than a tuned room temperature coil tightly wound around the sample, with a noise level which is a factor 3 better than for the volume coil. Our results suggest that mixed sensors are suitable for the integration of low-field MRI and MEG in a hybrid apparatus, where MEG and MRI would be recorded by SQUIDs and mixed sensors, respectively.

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Hybrid ultra‐low‐field MRI and magnetoencephalography system based on a commercial whole‐head neuromagnetometer

Cited by 20 publications

References 0 publications

Kinetic inductance magnetometer

Kinetic inductance magnetometer

Adaptive suppression of power line interference in ultra-low field magnetic resonance imaging in an unshielded environment

NMR Detection at 8.9 Mt With a GMR Based Sensor Coupled to a Superconducting Nb Flux Transformer

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