Resolution Nuclear Magnetic Resonance Imaging Research Articles

NMR micro-imaging for visualizing freezing behaviour in plant tissues

High resolution nuclear magnetic resonance imaging (i.e., NMR microscopy) was used to study the freezing behaviors in wintering flower buds of azalea (Rhododendron japonicum), leaf and flower buds of full-moon maple (Acer japonicum) and leaf buds of Momi fir (Abies firma) and lilac (Syringa vulgaris). The images acquired predominantly reflected the density of mobile (i.e., non-ice) protons mainly from unfrozen water. By comparing these images taken at various subfreezing temperatures, we could successfully visualize typical extra-organ freezing in the florets of R. japonicum and shoot primordia of maple and fir and deep supercooling in the maple xylem and azalea pith. Extracellular freezing was also clearly seen in the bud scales and bark tissues of these species and primordial leaves of lilac. To correctly interpret the images, all the factors that affect image intensity at differing temperatures are considered but the water to ice transition is the most dominant. Other problems that may be encountered in the interpretation of the images are also considered. The results of our studies show that NMR microscopy allows dynamic and species specific freezing processes of various plant tissues in a single specimen to be noninvasively visualized. Further, the information obtained provides deeper insight into the diversity and mechanisms involved in freezing behaviors.

GW26-e1338 Carotid Plaque Characteristics Detected with High Resolution Nuclear Magnetic Resonance Imaging in Patients with Coronary Artery Disease

GW26-e1338 Carotid Plaque Characteristics Detected with High Resolution Nuclear Magnetic Resonance Imaging in Patients with Coronary Artery Disease

High Resolution NMR Imaging using a High Field Yokeless Permanent Magnet

We measured the homogeneity and stability of the magnetic field of a high field (about 1.04 tesla) yokeless permanent magnet with 40-mm gap for high resolution nuclear magnetic resonance (NMR) imaging. Homogeneity was evaluated using a 3-dimensional (3D) lattice phantom and 3D spin-echo imaging sequences. In the central sphere (20-mm diameter), peak-to-peak magnetic field inhomogeneity was about 60 ppm, and the root-mean-square was 8 ppm. We measured room temperature, magnet temperature, and NMR frequency of the magnet simultaneously every minute for about 68 hours with and without the thermal insulator of the magnet. A simple mathematical model described the magnet's thermal property. Based on magnet performance, we performed high resolution (up to [20 µm](2)) imaging with internal NMR lock sequences of several biological samples. Our results demonstrated the usefulness of the high field small yokeless permanent magnet for high resolution NMR imaging.

Visualisation of collagen fibrils in joint cartilage using STIM

The scanning transmission ion microscopy (STIM) method was used to investigate the collagen network structure of the articular cartilage from a pig's knee in comparison with high resolution nuclear magnetic resonance imaging (microscopic NMR-tomography) and polarised light microscopy (PLM). Single collagen fibrils down to 200 nm in diameter were visualised. It was proved that the cartilage collagen network consists partly of zones of oriented fibrils as suggested by NMR measurements. Radially oriented fibrils were found in the zone near the calcified zone (hypertrophic zone) of both tibia and femur, and in the tibial radial zone. Tangentially oriented fibrils were found in the femoral and tibial superficial zone and in a second zone of the femoral cartilage. Polarisation light microscopy reveals broader zones of orientation than it was found with STIM.

Visualizing the postembryonic development ofSarcophaga peregrina(flesh fly) by NMR microscopy

AbstractThe postembryonic development of the flesh fly was studied using high resolution nuclear magnetic resonance imaging. Because this development occurs in a puparium, this process cannot be observed directly using standard histological techniques. The remodelling of histolysing larval tissues to developing imaginal tissues including the yellow body, a transient alimentary structure, and the integration of the developed adult structure were revealed in the images. Most surprisingly it was found that a large gas space that forms in the central region of the prepupa moves to the dorso‐anterial region in less than 5 min due to the larval–pupal apolysis together with separation of the developing pupal epidermis from the puparium.

Diffusion and perfusion in high resolution NMR imaging and microscopy

Diffusion and perfusion phenomena under strong gradient fields (approximately 100 G/cm) are examined in high resolution nuclear magnetic resonance (NMR) imaging and microscopy, where diffusion-associated signal attenuation predominates over T1 and T2 relaxation decays. Image contrast based on the diffusion and microcirculation is discussed with experimental results obtained with a 7.0-T microscopy system. Ultimate resolution limit due to diffusion is investigated in high resolution NMR imaging and microscopy.

4724387 Method and apparatus for high resolution nuclear magnetic resonance imaging : Koich Sano, Shimbu Yamagata, Hideaki Koizumi, Yokohama, Japan assigned to Hitachi Ltd

4724387 Method and apparatus for high resolution nuclear magnetic resonance imaging : Koich Sano, Shimbu Yamagata, Hideaki Koizumi, Yokohama, Japan assigned to Hitachi Ltd

4724387 Method and apparatus for high resolution nuclear magnetic resonance imaging

In a nuclear magnetic resonance imaging method and apparatus, the center position of each of a plurality of gradient magnetic fields are controlled to shift the positions of sampling points in a plurality of reconstructed images of the same part so that they do not overlap with each other in a sampling interval. As the result, the number of sampling points is effectively increased, thereby increasing the spacial resolving power of reconstructed images by NMR signals.

A generalized formulation of diffusion effects in micron resolution nuclear magnetic resonance imaging.

A generalized formulation of the diffusion related nuclear magnetic resonance (NMR) signal is derived from a random walk model. Previous analyses performed in the NMR spectroscopy were the formulations of the diffusion related signal amplitude at a specific time, such as the spin echo formation time. They are, in general, not applicable to continuous time domain analyses. In this paper, we have extended the theory to the two-dimensional imaging case and derived an analytical formula useful for the computation of the diffusion affected signal as a function of continuous time for a time variant gradient. This formulation will be useful in NMR imaging, especially in NMR microscopy where the diffusion associated signal attenuation is serious due to the strong gradient fields (100-1000 G/cm), and at the same time data are acquired continuously for the acquisition period. In addition to the loss of the resolution and signal-to-noise ratio due to the random phase fluctuation by diffusion, the variation of the intensity during the data acquisition period introduces a line broadening whose full width at half-maximum is found to be much larger than the bandwidth-limited resolution or diffusion related intrinsic resolution. This line spreading effect is integrated in a computer simulation and is evaluated as an integral part of the overall diffusion effects in micron resolution NMR imaging or NMR microscopy.

High resolution nuclear magnetic resonance imaging of the spinal cord in experimental demyelinating disease.

Chronic recurrent experimental allergic encephalomyelitis was induced in a strain 13 guinea pig by inoculation of isologous spinal cord homogenate. The spinal cord was obtained after perfusion with 4% paraformaldehyde and examined with nuclear magnetic resonance (NMR) imaging. Proton NMR spin echo images (repetition time: 3 s; echo times: 20 and 60 ms) were obtained from intact, isolated spinal cord in a 4.7 Tesla, 50 mm bore magnet. The slice thickness of the images was 380 microns and the inplane resolution was 40 X 40 microns. The images showed superficial areas of low signal intensity in the lateroventral regions of the white matter, in some instances with a seam of higher signal intensity. Neuropathologically, these abnormalities corresponded exactly to areas of demyelination. Control images did not show these abnormalities. The present high resolution imaging allowed a correlation between demyelination and abnormal NMR signals in a small laboratory animal with an inflammatory demyelinating disease.

High resolution nuclear magnetic resonance imaging of pig knees at 4.7 T

We present images of the pig knee joint which illustrate the resolution that is easily obtainable in high field (4.7 T) NMR imaging. We also describe a variant of the birdcage resonator which utilizes a novel tuning mechanism of simple construction.