Constant time imaging approaches to NMR microscopy

Choi, Sung‐Min; Tang, Xiaowu Shirley; Cory, David G.

doi:10.1002/(sici)1098-1098(1997)8:3<263::aid-ima4>3.0.co;2-8

Cited by 66 publications

(60 citation statements)

References 5 publications

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“…It is worth noting that the constant time imaging (CTI) technique [13] (which replaces the readout gradient with another spin-warp phase-encoding gradient) is an excellent alternative method for microscopic MRI applications, as it produces images with fewer artifacts and somewhat improved sensitivity (due to reduced diffusion attenuation). However, CTI requires a largo amount of acquisitions to collect a complete data set, as the method involves sampling each k-space point one at a time, whereas the readout method samples a line of points at a time.…”

Section: Resultsmentioning

confidence: 99%

Combined confocal and magnetic resonance microscopy

et al. 2002

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Confocal fluorescence optical microscopy and magnetic resonance microscopy are each used to study live cells in a minimally invasive way. Both techniques provide complementar3, information. Therefore, by examining cells simultaneously with both methodologies, more detailed information is obtained than is possible with each microscope individually. In this paper two configurations of a combined confocal and magnetic resonance microscope are described. The first configuration is capable of studying large single cells or three-dimensional cell agglomerates, whereas the second configuration is designed for the investigation of monolayers of mammalian cells. In both cases the sample compartment is part of a temperature regulated perfusion system. Images obtained with the combined system ate shown for Xenopus laevis oocytes, model JB6 tumor spheroids, anda single layer of Chinese hamster ovary cells. Finally, potential applications of the combined microscope are discussed. lntroductionConfocal fluorescence optical microscopy (OM) and magnetic resonance microscopy (MRM) are extensively used to study living cells in a minimally or noninvasive way [I-4]. Both methods have their advantages and disadvantages and provide complementary information. With OM, images can be obtained with a high spatial resolution (1 ~tm or less) in a short time (seconds). These images can be used to detect small concentrations of biochemicals within a cell or to determine its morphology. This technique, however, requires the use of fluorescent labels and is limited to transparent samples. In contrast, the images obtained with MRM are considerably less well-resolved (10-30 ~tm for ah image of the water distribution), and take a long time to acquire (often several minutes to hours). Despite these shortcomings, MRM is still very useful since it can be used irrespective of the opacity of the sample. Furthermore, MRM provides a wealth of additional biophysical and biochemical information such as the N M R T~ and NMR T 2 relaxation rates, the diffusion coefficient of intra-and extracellular water, and the concentrations of mobile, low-molecular-weight cellular metabolites [3][4][5].

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Section: Resultsmentioning

confidence: 99%

Combined confocal and magnetic resonance microscopy

et al. 2002

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“…More stable labeling of lymphocytes was achieved with [ 125 I]IUdR which stably incorporates into DNA of labeled cells [12]. Although, successful non-invasive imaging with [ [14,15], and could be applied to gamma camera and PET imaging of radiolabeled lymphocytes, such an approach has never been tested. Another shortcoming of the ex vivo radiolabeling approach is the limited period of monitoring which is due to radiolabel decay and/or biological clearance.…”

Section: H] and [mentioning

confidence: 99%

“…Recent developments in MR imaging have enabled in vivo imaging at near microscopic resolution [15][16][17]. In order to visualize and track stem and progenitor cells by MR imaging, it is necessary to tag cells magnetically.…”

Section: H] and [mentioning

confidence: 99%

PET imaging of adoptive progenitor cell therapies.

Gelovani¹

2008

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Objectives. The overall objective of this application is to develop novel technologies for non-invasive imaging of adoptive stem cell-based therapies with positron emission tomography (PET) that would be applicable to human patients. To achieve this objective, stem cells will be genetically labeled with a PETreporter gene and repetitively imaged to assess their distribution, migration, differentiation, and persistence using a radiolabeled reporter probe. This new imaging technology will be tested in adoptive progenitor cellbased therapy models in animals, including: delivery pro-apoptotic genes to tumors, and T-cell reconstitution for immunostimulatory therapy during allogeneic bone marrow progenitor cell transplantation.Technical and Scientific Merits. Non-invasive whole body imaging would significantly aid in the development and clinical implementation of various adoptive progenitor cell-based therapies by providing the means for non-invasive monitoring of the fate of injected progenitor cells over a long period of observation. The proposed imaging approaches could help to address several questions related to stem cell migration and homing, their long-term viability, and their subsequent differentiation. The ability to image these processes non-invasively in 3D and repetitively over a long period of time is very important and will help the development and clinical application of various strategies to control and direct stem cell migration and differentiation.Approach to accomplish the work. Stem cells will be genetically with a reporter gene which will allow for repetitive non-invasive "tracking" of the migration and localization of genetically labeled stem cells and their progeny. This is a radically new approach that is being developed for future human applications and should allow for a long term (many years) repetitive imaging of the fate of tissues that develop from the transplanted stem cells.Why the approach is appropriate. The novel approach to stem cell imaging is proposed to circumvent the major limitation of in vitro radiolabeling -the eventual radiolabel decay. Stable transduction of stem cells in vitro would allow for the selection of high quality stem cells with optimal functional parameters of the transduced reporter systems. The use of a long-lived radioisotope 124 I to label a highly specific reporter gene probe will allow for ex vivo labeling of stem cells and their imaging immediately after injection and during the following next week. The use of short-lived radioisotopes (i.e., 18 F) to label highly specific reporter gene probes will allow repetitive PET imaging for the assessment of to stem cell migration, targeting, differentiation, and long-term viability of stem cell-derived tissues.Qualifications of the research team and resources. An established research team of experts in various disciplines has been assembled at MD Anderson Cancer Center (MDACC) over the past two years including the PI, senior co-investigators and collaborators. The participants of this team are recognized i...

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“…76 This technique, known as single point imaging (SPI) (also referenced as constant time imaging, CTI), has been widely applied, in different modified forms, to solid-state NMR imaging. [77][78][79][80] The sensitivity and resolution of SPI have been well explored in a pioneering paper by Gravina and Cory. 81 The method essentially consists of generating k-space information in the presence of pure phase-encoding static gradients and is shown to provide artifact free images, because it does not measure the time evolution of the magnetization.…”

Section: Single Point Imagingmentioning

confidence: 99%

Radio frequency continuous‐wave and time‐domain EPR imaging and Overhauser‐enhanced magnetic resonance imaging of small animals: instrumental developments and comparison of relative merits for functional imaging

et al. 2004

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Electron paramagnetic resonance (EPR) imaging in the continuous wave (CW) and time-domain modes, as well as Overhauser-enhanced magnetic resonance imaging in vivo is described. The review is based mainly on the CW and time-domain EPR instrumentation at 300 MHz developed in our laboratory, and the relative merits of these methods for functional in vivo imaging of small animals to assess hypoxia and tissue redox status are described. Overhauser imaging of small animals at magnetic fields in the range 10-15 mT that is being carried out in our laboratory for tumor imaging and the evaluation of tumor hypoxia based on quantitative evaluation of Overhauser enhancement is also described. Alternate approaches to spectral-spatial imaging using the transverse decay constants to infer in situ line widths and hence in vivo pO 2 using CW and time-domain EPR imaging are also discussed. The nature of the spin probes used, the quality of the images obtained in all the three methods, the achievable resolution, limitations and possible future directions in small animal functional imaging with these modalities are summarized.

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Constant time imaging approaches to NMR microscopy

Cited by 66 publications

References 5 publications

Combined confocal and magnetic resonance microscopy

Combined confocal and magnetic resonance microscopy

PET imaging of adoptive progenitor cell therapies.

Radio frequency continuous‐wave and time‐domain EPR imaging and Overhauser‐enhanced magnetic resonance imaging of small animals: instrumental developments and comparison of relative merits for functional imaging

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