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Anders J, Handwerker J, Ortmanns M, Boero G. A low-power high-sensitivity single-chip receiver for NMR microscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 266:41-50. [PMID: 27011023 DOI: 10.1016/j.jmr.2016.03.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 03/08/2016] [Accepted: 03/09/2016] [Indexed: 06/05/2023]
Abstract
In this paper, we present a fully-integrated receiver for NMR microscopy applications manufactured in a 0.13μm CMOS technology. The design co-integrates a 10-turn planar detection coil together with a complete quadrature, low-IF downconversion receiver on a single chip, which operates from a single 1.5V supply with a total power dissipation of 18mW. The detector's measured time-domain spin sensitivity is 3×10(13)(1)Hspins/Hz at 7T. Additionally, the paper discusses two important aspects of NMR microscopy using planar detection coils: the link between the detection coil's spin sensitivity and the achievable image SNR and the correction of image artifacts induced by the inhomogeneous sensitivity profile of planar detection coils. More specifically, we derive analytical expressions for both the theoretical image SNR as a function of the coil's spin sensitivity and the sensitivity correction for a known coil sensitivity profile in CTI MR imaging experiments. Both expressions are validated using measured data in the imaging section of the paper. Thanks to the improved spin sensitivity of the utilized integrated receiver chip compared to a previously presented design, we were able to obtain sensitivity corrected images in a 7T spectroscopy magnet with isotropic resolutions of 9.6μm and 5μm with single-shot SNRs of 37 and 15 in relatively short imaging times of 4.4h and 24h, respectively.
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Affiliation(s)
- Jens Anders
- University of Ulm, Institute of Microelectronics, Albert-Einstein-Allee 43, D-89081 Ulm, Germany; Ecole Polytechnique Federale de Lausanne (EPFL), Institute of Microengineering, Station 17, CH-1015 Lausanne, Switzerland.
| | - Jonas Handwerker
- University of Ulm, Institute of Microelectronics, Albert-Einstein-Allee 43, D-89081 Ulm, Germany
| | - Maurits Ortmanns
- University of Ulm, Institute of Microelectronics, Albert-Einstein-Allee 43, D-89081 Ulm, Germany
| | - Giovanni Boero
- Ecole Polytechnique Federale de Lausanne (EPFL), Institute of Microengineering, Station 17, CH-1015 Lausanne, Switzerland
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Goebel L, Müller A, Bücker A, Madry H. High resolution MRI imaging at 9.4 Tesla of the osteochondral unit in a translational model of articular cartilage repair. BMC Musculoskelet Disord 2015; 16:91. [PMID: 25888208 PMCID: PMC4404065 DOI: 10.1186/s12891-015-0543-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 03/27/2015] [Indexed: 12/13/2022] Open
Abstract
Background Non-destructive structural evaluation of the osteochondral unit is challenging. Here, the capability of high-field magnetic resonance imaging (μMRI) at 9.4 Tesla (T) was explored to examine osteochondral repair ex vivo in a preclinical large animal model. A specific aim of this study was to detect recently described alterations of the subchondral bone associated with cartilage repair. Methods Osteochondral samples of medial femoral condyles from adult ewes containing full-thickness articular cartilage defects treated with marrow stimulation were obtained after 6 month in vivo and scanned in a 9.4 T μMRI. Ex vivo imaging of small osteochondral samples (typical volume: 1–2 cm3) at μMRI was optimised by variation of repetition time (TR), time echo (TE), flip angle (FA), spatial resolution and number of excitations (NEX) from standard MultiSliceMultiEcho (MSME) and three-dimensional (3D) spoiled GradientEcho (SGE) sequences. Results A 3D SGE sequence with the parameters: TR = 10 ms, TE = 3 ms, FA = 10 °, voxel size = 120 × 120 × 120 μm3 and NEX = 10 resulted in the best fitting for sample size, image quality, scanning time and artifacts. An isovolumetric voxel shape allowed for multiplanar reconstructions. Within the osteochondral unit articular cartilage, cartilaginous repair tissue and bone marrow could clearly be distinguished from the subchondral bone plate and subarticular spongiosa. Specific alterations of the osteochondral unit associated with cartilage repair such as persistent drill holes, subchondral bone cysts, sclerosis of the subchondral bone plate and of the subarticular spongiosa and intralesional osteophytes were precisely detected. Conclusions High resolution, non-destructive ex vivo analysis of the entire osteochondral unit in a preclinical large animal model that is sufficient for further analyses is possible using μMRI at 9.4 T. In particular, 9.4 T is capable of accurately depicting alterations of the subchondral bone that are associated with osteochondral repair.
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Affiliation(s)
- Lars Goebel
- Center of Experimental Orthopaedics, Saarland University Medical Center, Kirrberger Straße, Building 37, Homburg/Saar, D-66421, Germany. .,Department of Orthopaedic Surgery, Saarland University Medical Center, Kirrberger Straße, Building 37, Homburg/Saar, D-66421, Germany. .,Cartilage Net of the Greater Region, University of the Greater Region, Homburg/Saar, D-66421, Germany.
| | - Andreas Müller
- Department of Diagnostic and Interventional Radiology, Saarland University Medical Center, Kirrberger Straße, Building 57, Homburg/Saar, D-66421, Germany.
| | - Arno Bücker
- Department of Diagnostic and Interventional Radiology, Saarland University Medical Center, Kirrberger Straße, Building 57, Homburg/Saar, D-66421, Germany.
| | - Henning Madry
- Center of Experimental Orthopaedics, Saarland University Medical Center, Kirrberger Straße, Building 37, Homburg/Saar, D-66421, Germany. .,Department of Orthopaedic Surgery, Saarland University Medical Center, Kirrberger Straße, Building 37, Homburg/Saar, D-66421, Germany. .,Cartilage Net of the Greater Region, University of the Greater Region, Homburg/Saar, D-66421, Germany.
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Chiwan Koo, Godley RF, McDougall MP, Wright SM, Han A. A microfluidically cryocooled spiral microcoil with inductive coupling for MR microscopy. IEEE Trans Biomed Eng 2014; 61:76-84. [PMID: 23955689 DOI: 10.1109/tbme.2013.2276770] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/06/2024]
Abstract
Magnetic resonance (MR) microscopy typically employs microcoils for enhanced local signal-to-noise ratio (SNR). Planar (surface) microcoils, in particular, offer the potential to be configured into array elements as well as to enable the imaging of extremely small samples because of the uniformity and precision provided by microfabrication techniques. Microcoils, in general, however, are copper-loss dominant, and cryocooling methods have been successfully used to improve the SNR. Cryocooling of the matching network elements, in addition to the coil itself, has shown to provide the most improvement, but can be challenging with respect to cryostat requirements, cabling, and tuning. Here we present the development of a microfluidically cryocooled spiral microcoil with integrated microfabricated parallel plate capacitors, allowing for localized cryocooling of both the microcoil and the on-chip resonating capacitor to increase the SNR while keeping the sample-to-coil distance within the most sensitive imaging range of the microcoil. Inductive coupling was used instead of a direct transmission line connection to eliminate the physical connection between the microcoil and the tuning network so that a single cryocooling microfluidic channel could enclose both the microcoil and the on-chip capacitor with minimum loss in cooling capacity. Comparisons between the cooled and uncooled cases were made via Q-factor measurements and agreed well with the theoretically achievable improvement: the cooled integrated capacitor coil with inductive coupling achieved a factor of 2.6 improvement in Q-factor over a reference coil conventionally matched and tuned with high- Q varactors and capacitively connected to the transmission line.
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Même S, Joudiou N, Szeremeta F, Mispelter J, Louat F, Decoville M, Locker D, Beloeil JC. In vivo magnetic resonance microscopy of Drosophilae at 9.4 T. Magn Reson Imaging 2012; 31:109-19. [PMID: 22898691 DOI: 10.1016/j.mri.2012.06.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 05/16/2012] [Accepted: 06/25/2012] [Indexed: 10/28/2022]
Abstract
In preclinical research, genetic studies have made considerable progress as a result of the development of transgenic animal models of human diseases. Consequently, there is now a need for higher resolution MRI to provide finer details for studies of small animals (rats, mice) or very small animals (insects). One way to address this issue is to work with high-magnetic-field spectrometers (dedicated to small animal imaging) with strong magnetic field gradients. It is also necessary to develop a complete methodology (transmit/receive coil, pulse sequence, fixing system, air supply, anesthesia capabilities, etc.). In this study, we developed noninvasive protocols, both in vitro and in vivo (from coil construction to image generation), for drosophila MRI at 9.4 T. The 10 10 80-μm resolution makes it possible to visualize whole drosophila (head, thorax, abdomen) and internal organs (ovaries, longitudinal and transverse muscles, bowel, proboscis, antennae and optical lobes). We also provide some results obtained with a Drosophila model of muscle degeneration. This opens the way for new applications of structural genetic modification studies using MRI of drosophila.
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Affiliation(s)
- Sandra Même
- Centre de Biophysique Moléculaire, CNRS UPR4301, Orléans, France.
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Flint JJ, Hansen B, Portnoy S, Lee CH, King MA, Fey M, Vincent F, Stanisz GJ, Vestergaard-Poulsen P, Blackband SJ. Magnetic resonance microscopy of human and porcine neurons and cellular processes. Neuroimage 2012; 60:1404-11. [PMID: 22281672 DOI: 10.1016/j.neuroimage.2012.01.050] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 12/14/2011] [Accepted: 01/05/2012] [Indexed: 11/26/2022] Open
Abstract
With its unparalleled ability to safely generate high-contrast images of soft tissues, magnetic resonance imaging (MRI) has remained at the forefront of diagnostic clinical medicine. Unfortunately due to resolution limitations, clinical scans are most useful for detecting macroscopic structural changes associated with a small number of pathologies. Moreover, due to a longstanding inability to directly observe magnetic resonance (MR) signal behavior at the cellular level, such information is poorly characterized and generally must be inferred. With the advent of the MR microscope in 1986 came the ability to measure MR signal properties of theretofore unobservable tissue structures. Recently, further improvements in hardware technology have made possible the ability to visualize mammalian cellular structure. In the current study, we expand upon previous work by imaging the neuronal cell bodies and processes of human and porcine α-motor neurons. Complimentary imaging studies are conducted in pig tissue in order to demonstrate qualitative similarities to human samples. Also, apparent diffusion coefficient (ADC) maps were generated inside porcine α-motor neuron cell bodies and portions of their largest processes (mean=1.7 ± 0.5 μm²/ms based on 53 pixels) as well as in areas containing a mixture of extracellular space, microvasculature, and neuropil (0.59 ± 0.37 μm²/ms based on 33 pixels). Three-dimensional reconstruction of MR images containing α-motor neurons shows the spatial arrangement of neuronal projections between adjacent cells. Such advancements in imaging portend the ability to construct accurate models of MR signal behavior based on direct observation and measurement of the components which comprise functional tissues. These tools would not only be useful for improving our interpretation of macroscopic MRI performed in the clinic, but they could potentially be used to develop new methods of differential diagnosis to aid in the early detection of a multitude of neuropathologies.
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Affiliation(s)
- Jeremy J Flint
- McKnight Brain Institute, Dep. of Neuroscience, University of Florida, FL, USA.
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Baxan N, Kahlert U, Maciaczyk J, Nikkhah G, Hennig J, von Elverfeldt D. Microcoil-based MR phase imaging and manganese enhanced microscopy of glial tumor neurospheres with direct optical correlation. Magn Reson Med 2011; 68:86-97. [PMID: 22127877 DOI: 10.1002/mrm.23208] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2010] [Revised: 07/06/2011] [Accepted: 08/16/2011] [Indexed: 12/22/2022]
Abstract
Susceptibility differences among tissues were recently used for highlighting complementary contrast in MRI different from the conventional T(1), T(2), or spin density contrasts. This method, based on the signal phase, previously showed improved image contrast of human or rodent neuroarchitecture in vivo, although direct MR phase imaging of cellular architecture was not available until recently. In this study, we present for the first time the ability of microcoil-based phase MRI to resolve the structure of human glioma neurospheres at significantly improved resolutions (10 × 10 μm(2)) with direct optical image correlation. The manganese chloride property to function as a T(1) contrast agent enabled a closer examination of cell physiology with MRI. Specifically the temporal changes of manganese chloride uptake, retention and release time within and from individual clusters were assessed. The optimal manganese chloride concentration for improved MR signal enhancement was determined while keeping the cellular viability unaffected. The presented results demonstrate the possibilities to reveal structural and functional observation of living glioblastoma human-derived cells. This was achieved through the combination of highly sensitive microcoils, high magnetic field, and methods designed to maximize contrast to noise ratio. The presented approach may provide a powerful multimodal tool that merges structural and functional information of submilimeter biological samples.
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Affiliation(s)
- Nicoleta Baxan
- Department of Radiology, Medical Physics, University Medical Center, Freiburg, Germany.
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