SQUID detected NMR in microtesla magnetic fields

Matlachov, A.N.; Volegov, P. L.; Espy, Michelle A.; George, John; Kraus, R.H.

doi:10.1016/j.jmr.2004.05.015

Cited by 90 publications

(63 citation statements)

References 30 publications

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“…To overcome the sensitivity loss of Faraday detection at low frequencies, ultrasensitive magnetometers based on the Superconducting QUantum Interference Device (SQUID) (16) are used to detect NMR and MRI signals (17)(18)(19)(20)(21)(22)(23)(24). Recently, SQUID-based MRI systems capable of acquiring in vivo images have appeared.…”

Section: Introductionmentioning

confidence: 99%

SQUID-Detected Magnetic Resonance Imaging in Microtesla Fields

Clarke

Hatridge

Mößle

2007

Annu. Rev. Biomed. Eng.

195

121

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The use of very low noise magnetometers based on Superconducting QUantum Interference Devices (SQUIDs) enables nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) in microtesla magnetic fields. An untuned superconducting flux transformer coupled to a SQUID achieves a magnetic field noise of 10−15 T Hz−1/2. The frequency-independent response of this magnetometer combined with prepolarization of the nuclear spins yields an NMR signal that is independent of the Larmor frequency ω0. An MRI system operating in a field of 132 μT, corresponding to a proton frequency of 5.6 kHz, achieves an in-plane resolution of 0.7 × 0.7 mm2 in phantoms. Measurements of the longitudinal relaxation time T1 in different concentrations of agarose gel over five decades of frequency reveal much greater T1-differentiation at fields below a few millitesla. Microtesla MRI has the potential to image tumors with substantially greater T1-weighted contrast than is achievable in high fields in the absence of a contrast agent.

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Section: Introductionmentioning

confidence: 99%

SQUID-Detected Magnetic Resonance Imaging in Microtesla Fields

Clarke

Hatridge

Mößle

2007

Annu. Rev. Biomed. Eng.

195

121

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“…This fact greatly simplifies coil design and makes it possible to construct ULF MRI systems [18,24] that are simple, inexpensive, portable, and patient-friendly. Imaging at ULF offers additional benefits, including minimized susceptibility artifacts [16], enhanced T 1 contrast [28], and possibility of imaging in the presence of metal [20,29]. Moreover, ULF MRI is compatible with MEG as discussed below.…”

Section: Introductionmentioning

confidence: 99%

Parallel MRI at microtesla fields

Zotev

Volegov

Matlashov

et al. 2008

Journal of Magnetic Resonance

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Parallel imaging techniques have been widely used in high-field magnetic resonance imaging (MRI). Multiple receiver coils have been shown to improve image quality and allow accelerated image acquisition. Magnetic resonance imaging at ultra-low fields (ULF MRI) is a new imaging approach that uses SQUID (superconducting quantum interference device) sensors to measure the spatially encoded precession of pre-polarized nuclear spin populations at microtesla-range measurement fields. In this work, parallel imaging at microtesla fields is systematically studied for the first time. A seven-channel SQUID system, designed for both ULF MRI and magnetoencephalography (MEG), is used to acquire 3D images of a human hand, as well as 2D images of a large water phantom. The imaging is performed at 46 microtesla measurement field with pre-polarization at 40 mT. It is shown how the use of seven channels increases imaging field of view and improves signal-to-noise ratio for the hand images. A simple procedure for approximate correction of concomitant gradient artifacts is described. Noise propagation is analyzed experimentally, and the main source of correlated noise is identified. Accelerated imaging based on one-dimensional undersampling and 1D SENSE (sensitivity encoding) image reconstruction is studied in the case of the 2D phantom. Actual 3-fold imaging acceleration in comparison to single-average fully encoded Fourier imaging is demonstrated. These results show that parallel imaging methods are efficient in ULF MRI, and that imaging performance of SQUID-based instruments improves substantially as the number of channels is increased.

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“…However, after injecting gold particles in animals and irradiation them by 250 kV, X-rays caused tumor shrinkage and enhanced survival rate by four fold [128]. Gold nanoparticles are easily functionalized by thiol derivatives and open multimodal imaging perspectives.…”

Section: Gold Nanoparticlesmentioning

confidence: 99%

State of Art on Bioimaging by Nanoparticles in Hyperthermia and Thermometry: Visualization of Tissue Protein Targeting

Sharma¹,

Sharma²,

Chen³

2011

TONMJ

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Abstract:Heating tumors by nanoparticles and resistance in tumor cells to a high temperature is emerging as an effective tool as nanomedicine tool in cancer therapy. The art of thermal mapping in a tumor at various locations is emerging as the selective approach of hyperthermia to monitor temperature and treat the tumor. However, thermometry and tumor cell interaction with nanoparticles may monitor and evaluate the tumor cell survival after exposure to high physiological temperatures but show cytotoxicity. The design and application of 10-100 nano meter sized nanoparticles in tumor hyperthermia has emerged as an effective technology in hyperthermia imaging and treatment. The temperature and nanoparticle magnetic moment relationship is specific. Furthermore, there are two main issues that are unsolved as of yet. First issue is the relationship of tumor energy changes due to tumor magnetization by different nanoparticles. The second issue is the heat transfer behavior of the nanoparticle inside the tumor combined with hyperthermia and efficacy of combined modality on the tumor tissue temperature rise. In present study, we highlight that in vivo imaging such as MR thermometry, photoacuastic mapping of different tumor locations solve these issues to some extent. The art of combined use of hyperthermia by nanoparticles with hypoxia sensitive nitroimidazole radiosensitizers with chemotherapeutic drugs is highlighted to have a great impact on public health as alternative therapeutic oncology and monitoring therapy.

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SQUID detected NMR in microtesla magnetic fields

Cited by 90 publications

References 30 publications

SQUID-Detected Magnetic Resonance Imaging in Microtesla Fields

SQUID-Detected Magnetic Resonance Imaging in Microtesla Fields

Parallel MRI at microtesla fields

State of Art on Bioimaging by Nanoparticles in Hyperthermia and Thermometry: Visualization of Tissue Protein Targeting

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