@article {256, title = {Relaxivity of Gadolinium Complexes Detected by Atomic Magnetometry}, journal = {Magnetic Resonance in Medicine}, volume = {66}, year = {2011}, note = {Magn Reson Med799AVTimes Cited:1Cited References Count:23}, month = {Aug}, pages = {605-608}, abstract = {

Laser atomic magnetomeby is a portable and low-cost yet highly sensitive method for low magnetic field detection. In this work, the atomic magnetometer was used in a remote-detection geometry to measure the relaxivity of aqueous gadolinium-diethylenetriamine pentaacetic acid Gd(DTPA) at the Earth\&$\#$39;s magnetic field (40 mu T). The measured relaxivity of 9.7 +/- 2.0 s(-1) mM(-1) is consistent with field-cycling experiments measured at slightly higher magnetic fields, but no cryogens or strong and homogeneous magnetic field were required for this experiment. The field-independent sensitivity of 80 fT Hz(-1/2) allowed an in vitro detection limit of similar to 10 mu M Gd(DTPA) to be measured in aqueous buffer solution. The low detection limit and enhanced relaxivity of Gd-containing complexes at Earth\&$\#$39;s field motivate continued development of atomic magnetometry toward medical applications. Magn Reson Med 66:605-608, 2011. (C) 2011 Wiley-Liss, Inc.

}, keywords = {nmr}, isbn = {0740-3194}, doi = {Doi 10.1002/Mrm.22811}, url = {://WOS:000293256800033}, author = {Michalak, D. J. and Xu, S. J. and Lowery, T. J. and Crawford, C. W. and Ledbetter, M. and Bouchard, L. S. and Wemmer, D. E. and Budker, D. and Pines, A.} } @article {272, title = {Picomolar sensitivity MRI and photoacoustic imaging of cobalt nanoparticles}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {106}, year = {2009}, note = {P Natl Acad Sci USA420HDTimes Cited:43Cited References Count:41}, month = {Mar 17}, pages = {4085-4089}, abstract = {

Multimodality imaging based on complementary detection principles has broad clinical applications and promises to improve the accuracy of medical diagnosis. This means that a tracer particle advantageously incorporates multiple functionalities into a single delivery vehicle. In the present work, we explore a unique combination of MRI and photoacoustic tomography (PAT) to detect picomolar concentrations of nanoparticles. The nanoconstruct consists of ferromagnetic (Co) particles coated with gold (Au) for biocompatibility and a unique shape that enables optical absorption over a broad range of frequencies. The end result is a dual-modality probe useful for the detection of trace amounts of nanoparticles in biological tissues, in which MRI provides volume detection, whereas PAT performs edge detection.

}, keywords = {cancer}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0813019106}, url = {://WOS:000264278800008}, author = {Bouchard, L. S. and Anwar, M. S. and Liu, G. L. and Hann, B. and Xie, Z. H. and Gray, J. W. and Wang, X. D. and Pines, A. and Chen, F. F.} } @article {273, title = {Flow in Porous Metallic Materials: A Magnetic Resonance Imaging Study}, journal = {Journal of Magnetic Resonance Imaging}, volume = {28}, year = {2008}, note = {J Magn Reson Imaging367QCTimes Cited:5Cited References Count:22}, month = {Nov}, pages = {1299-1302}, abstract = {

Purpose: To visualize flow dynamics of analytes inside porous metallic materials with laser-detected magnetic resonance imaging (MRI).Materials and Methods: We examine the flow of nuclear-polarized water in a porous stainless steel cylinder. Laser-detected MRI utilizes a sensitive optical atomic magnetometer as the detector. Imaging was performed in a remote-detection mode: the encoding was conducted in the Earth\&$\#$39;s magnetic field, and detection is conducted downstream of the encoding location. Conventional MRI (7T) was also performed for comparison.Results: Laser-detected MRI clearly showed MR images of water flowing through the sample, whereas conventional MRI provided no image.Conclusion: We demonstrated the viability of laser-detected MRI at low-field for studying porous metallic materials, extending MRI techniques to a new group of systems that is normally not accessible to conventional MRI.

}, keywords = {mri}, isbn = {1053-1807}, doi = {Doi 10.1002/Jmri.21532}, url = {://WOS:000260566100033}, author = {Xu, S. J. and Harel, E. and Michalak, D. J. and Crawford, C. W. and Budker, D. and Pines, A.} } @article {281, title = {Fluid-flow characterization with nuclear spins without magnetic resonance}, journal = {Applied Physics Letters}, volume = {93}, year = {2008}, note = {Appl Phys Lett345DHTimes Cited:2Cited References Count:20}, month = {Sep 1}, abstract = {

A technique for noninvasive monitoring of flow inside metallic enclosures using laser-based atomic magnetometry is introduced. The analyte is labeled via nuclear magnetization by magnets, thereby combining the polarization and encoding steps. No radiofrequency or audiofrequency pulses are involved. We demonstrate detection of flow inside an aluminum pipe with an inner diameter of 4.9 mm that has a constriction with a diameter of 1.6 mm and a length of 6.4 mm. The results agree with a model of spin density and relaxation indicating that our technique allows for fast, quantitative, and noninvasive diagnostics of flow with potential applications discussed below. (c) 2008 American Institute of Physics.

}, keywords = {mri}, isbn = {0003-6951}, doi = {Doi 10.1063/1.2977773}, url = {://WOS:000258975800042}, author = {Crawford, C. W. and Xu, S. J. and Siegel, E. J. and Budker, D. and Pines, A.} } @article {275, title = {Remote detection of nuclear magnetic resonance with an anisotropic magnetoresistive sensor}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {105}, year = {2008}, note = {P Natl Acad Sci USA266XBTimes Cited:8Cited References Count:17}, month = {Feb 19}, pages = {2271-2273}, abstract = {

We report the detection of nuclear magnetic resonance (NMR) using an anisotropic magnetoresistive (AMR) sensor. A \"remote-detection\" arrangement was used in which protons in flowing water were prepolarized in the field of a superconducting NMR magnet, adiabatically inverted, and subsequently detected with an AMR sensor situated downstream from the magnet and the adiabatic inverter. AMR sensing is well suited for NMR detection in microfluidic \"lab-on-a-chip\" applications because the sensors are small, typically on the order of 10 mu m. An estimate of the sensitivity for an optimized system indicates that approximate to 6 x 10(13) protons in a volume of 1,000 mu m(3), prepolarized in a 10-kG magnetic field, can be detected with a signal-to-noise ratio of 3 in a 1-Hz bandwidth. This level of sensitivity is competitive with that demonstrated by microcoils in superconducting magnets and with the projected sensitivity of microfabricated atomic magnetometers.

}, keywords = {mri}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0712129105}, url = {://WOS:000253469900006}, author = {Verpillat, F. and Ledbetter, M. P. and Xu, S. and Michalak, D. J. and Hilty, C. and Bouchard, L. S. and Antonijevic, S. and Budker, D. and Pines, A.} } @article {274, title = {Submillimeter-resolution magnetic resonance imaging at the Earth{\textquoteright}s magnetic field with an atomic magnetometer}, journal = {Physical Review A}, volume = {78}, year = {2008}, note = {Phys Rev A333VGTimes Cited:18Cited References Count:24}, month = {Jul}, abstract = {

Magnetic resonance imaging in the Earth\&$\#$39;s magnetic field is achieved using a sensitive atomic magnetometer for detection. We demonstrate images with a submillimeter resolution by recording the flow of two water paths meeting at a T-shaped mixer. The high homogeneity of the Earth\&$\#$39;s field allows the use of weak gradient fields which circumvent the concomitant-field effect. To distinguish the two input channels, we employed selective polarization, which is a unique and noninvasive labeling method for low-field magnetic resonance imaging. Our technique imposes minimal physical constraints on the object under study, in contrast to conventional high-field magnetic resonance imaging. This technique is applicable for microfluidic imaging in laboratory-on-a-chip devices.

}, keywords = {nmr}, isbn = {1050-2947}, doi = {Doi 10.1103/Physreva.78.013404}, url = {://WOS:000258180300141}, author = {Xu, S. and Crawford, C. W. and Rochester, S. and Yashchuk, V. and Budker, D. and Pines, A.} } @article {279, title = {Zero-field remote detection of NMR with a microfabricated atomic magnetometer}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {105}, year = {2008}, note = {P Natl Acad Sci USA266XBTimes Cited:37Cited References Count:26}, month = {Feb 19}, pages = {2286-2290}, abstract = {

We demonstrate remote detection of nuclear magnetic resonance (NMR) with a microchip sensor consisting of a microfluidic channel and a microfabricated vapor cell (the heart of an atomic magnetometer). Detection occurs at zero magnetic field, which allows operation of the magnetometer in the spin-exchange relaxation-free (SERF) regime and increases the proximity of sensor and sample by eliminating the need for a solenoid to create a leading field. We achieve pulsed NMR linewidths of 26 Hz, limited, we believe, by the residence time and flow dispersion in the encoding region. In a fully optimized system, we estimate that for 1 s of integration, 7 x 10(13) protons in a volume of 1 mm(3), prepolarized in a 10-kG field, can be detected with a signal-to-noise ratio of approximate to 3. This level of sensitivity is competitive with that demonstrated by microcoils in 100-kG magnetic fields, without requiring superconducting magnets.

}, keywords = {mri}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0711505105}, url = {://WOS:000253469900009}, author = {Ledbetter, M. P. and Savukov, I. M. and Budker, D. and Shah, V. and Knappe, S. and Kitching, J. and Michalak, D. J. and Xu, S. and Pines, A.} } @article {293, title = {Application of atomic magnetometry in magnetic particle detection}, journal = {Applied Physics Letters}, volume = {89}, year = {2006}, note = {Appl Phys Lett112PJTimes Cited:9Cited References Count:18}, month = {Nov 27}, abstract = {

The authors demonstrate the detection of magnetic particles carried by water in a continuous flow using an atomic magnetic gradiometer. Studies on three types of magnetic particles are presented: a single cobalt particle (diameter similar to 150 mu m, multidomain), a suspension of superparamagnetic magnetite particles (diameter similar to 1 mu m), and ferromagnetic cobalt nanoparticles (diameter similar to 10 nm). Estimated detection limits are 20 mu m diameter for a single cobalt particle at a water flow rate of 30 ml/min, 5x10(3) magnetite particles at 160 ml/min, and 50 pl for the ferromagnetic fluid of cobalt nanoparticles at 130 ml/min. Possible applications of their method are discussed.

}, keywords = {system}, isbn = {0003-6951}, doi = {Doi 10.1063/1.2400077}, url = {://WOS:000242538500151}, author = {Xu, S. and Donaldson, M. H. and Pines, A. and Rochester, S. M. and Budker, D. and Yashchuk, V. V.} } @article {292, title = {Magnetic resonance imaging with an optical atomic magnetometer}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {103}, year = {2006}, note = {P Natl Acad Sci USA077NITimes Cited:58Cited References Count:18}, month = {Aug 22}, pages = {12668-12671}, abstract = {

We report an approach for the detection of magnetic resonance imaging without superconducting magnets and cryogenics: optical atomic magnetometry. This technique possesses a high sensitivity independent of the strength of the static magnetic field, extending the applicability of magnetic resonance imaging to low magnetic fields and eliminating imaging artifacts associated with high fields. By coupling with a remote-detection scheme, thereby improving the filling factor of the sample, we obtained time-resolved flow images of water with a temporal resolution of 0.1 s and spatial resolutions of 1.6 mm perpendicular to the flow and 4.5 mm along the flow. Potentially inexpensive, compact, and mobile, our technique provides a viable alternative for MRI detection with substantially enhanced sensitivity and time resolution for various situations where traditional MRI is not optimal.

}, keywords = {gas}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0605396103}, url = {://WOS:000240035900006}, author = {Xu, S. J. and Yashchuk, V. V. and Donaldson, M. H. and Rochester, S. M. and Budker, D. and Pines, A.} } @article {406, title = {Multiple-quantum magic-angle spinning and dynamic-angle spinning NMR spectroscopy of quadrupolar nuclei}, journal = {Solid State Nuclear Magnetic Resonance}, volume = {8}, year = {1997}, note = {Solid State Nucl MagWy629Times Cited:60Cited References Count:40}, month = {Mar}, pages = {1-16}, abstract = {

Several aspects of the Multiple-Quantum Magic-Angle Spinning (MQMAS) technique (L, Frydman and J,S, Harwood, J, Am, Chem, Sec., 117 (1995) 5367) are compared with Dynamic-Angle Spinning (DAS), Examples of MQMAS spectra are shown for I = 3/2 nuclei with C-Q up to 3.6 MHz, and for: Al-27 (I = 5/2) with C-Q up to 10 MHz. The MQMAS linewidth is largely independent of the magnitude of the homonuclear dipolar interaction, while the spinning sideband manifold is similar to that observed in DAS experiments, MQMAS is technically simple and routinely useful for studying nuclei with short spin-lattice relaxation times, but care must be taken in its use for quantitative studies as the excitation of the triple-quantum coherence is not uniform, In this regard, MQMAS is most useful for samples with small quadrupolar coupling constants, In the specific case of O-17, DAS would give spectra with excellent resolution in comparison to MQMAS, The different advantages of DAS and MQMAS make them useful complementary techniques in many cases,Two additional methods are also presented for extracting the chemical shift anisotropy (CSA) directly for quadrupolar nuclei using the multiple-quantum scheme, (C) 1997 Elsevier Science B,V.

}, keywords = {rb-87}, isbn = {0926-2040}, doi = {Doi 10.1016/S0926-2040(96)01277-5}, url = {://WOS:A1997WY62900001}, author = {Wang, S. H. and Xu, Z. and Baltisberger, J. H. and Bull, L. M. and Stebbins, J. F. and Pines, A.} } @article {435, title = {Triple-quantum two-dimensional Al-27 magic-angle spinning nuclear magnetic resonance spectroscopic study of aluminosilicate and aluminate crystals and glasses}, journal = {Journal of the American Chemical Society}, volume = {118}, year = {1996}, note = {J Am Chem SocVa026Times Cited:139Cited References Count:31}, month = {Jul 31}, pages = {7209-7214}, abstract = {

A new two-dimensional magic-angle spinning NMR experiment(1,2) using multiple-quantum coherences of half-integer quadrupolar nuclei was used to study Al-27 sites in crystalline samples of leucite (KAlSi2O6), anorthite (CaAl2Si2O8), and kyanite (Al2SiO5), as well as CaAl2Si2O8 glass and a magnesium aluminoborate glass. In the crystals, multiple sites are partially resolved and new results for isotropic chemical shifts and quadrupolar parameters are derived, using data collected at a single magnetic field. Data for both leucite and anorthite are consistent with previous results that correlate chemical shifts with mean intertetrahedral bond angle. Signal can be obtained from sites with quadrupolar coupling constants as large as 9 MHz, but intensities are reduced. In the aluminoborate glass, peaks for sites with different Al coordination numbers are well separated. The lack of such features in CaAl2Si2O8 glass rules out the presence of significant quantities of AlO5 and AlO6 groups.

}, keywords = {anorthite}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja9606586}, url = {://WOS:A1996VA02600027}, author = {Baltisberger, J. H. and Xu, Z. and Stebbins, J. F. and Wang, S. H. and Pines, A.} }