• Proceedings of the KOSOMBE Conference
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• v.1994 no.05
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• pp.9-15
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• 1994

In last few decades, medical imaging techniques have been developed startling progress. Especially in MRI (Magnetic Resonance Imaging), many imaging techniques such as chemical shift imaging, flow imaging, diffusion and perfusion imaging, fast imaging, susceptibility imaging and functional imaging have been studied and many of them were well known as useful diagnostic instruments. In this paper, recently developing techniques, i.e., NMR microscopy, fringe field imaging and functional imaging will be presented.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.64-72
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• 2001

• Proceedings of the KOSOMBE Conference
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• v.1995 no.11
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• pp.247-249
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• 1995

A new localized imaging technique of reduced imaging time using a locally-linear gradient is proposed. Since most fast MR imaging methods need the whole k-space data corresponding to the whole imaging area, there are limitations in reducing the minimum imaging time. The imaging method proposed in this paper uses a specially-made gradient coil generating a local ramp-shape field and uniform field outside of the imaging area. Conventional imaging sequences can be used without any RF/gradient pulse sequence modifications. The proposed localized imaging technique has been implemented on a 2.0 Tesla whole-body system at KAIST and the imaging results show the utility of the proposed technique.

• Biomedical Science Letters
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• v.10 no.3
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• pp.285-291
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• 2004

To determine the magnetic resonance (MR) imaging findings and natural history of cerebral fat embolism in a cat model, and to correlate the MR imaging and histologic fmdings. Intemel carotid artery of 11 cats was injected with 0.1 ml of triolein. T2-weighted, T1-weighted and Gd-enhanced T1-weighted images were obtained serially for 2 hours, 1 days, 4 days, 1 week, 2 weeks and 3 weeks after embolization. Any abnormal signal intensity was evaluated. After MR imaging at 3 weeks, brain tissue was obtained for light microscopic (LM) examination using hematoxylin-eosin (HE) and Luxol fast blue staining, and for electron microscopic examination. The LM examination with HE staining revealed normal histological findings in the greater part of an embolized lesion. Cystic change was observed in the gray matter of 8 cats, while in the gray and white matter of 3 cats. At LM examination, Luxol fast blue, staining demonstrated demyelination around the cystic change occurring in the white matter, and EM examination of the embolized cortex revealed sporadic intracapillary fat vacuoles (n=11) and disruption of the blood-brain barrier (n=4). Most lesions were normal, however, and perivascular interstitial edema and cellular swelling were mild compared with the control side. The greater part of an embolized lesion showed reversible findings at MR and histological examination. Irreversible focal necrosis was, however, observed in gray and white matter at weeks 3.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.98-99
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• 1998

In this paper, an interleaved spiral scan imaging is investigated for an ultra fast MR imaging. The interleaved spiral technique has relative advantage over single shot spiral imaging with improved resolution and less inhomogeneity-related artifact. An improved reconstruction algorithm is devised with DC-offset correction. Some preliminary experimental results are shown at 1.0 Tesla and 3.0 Tesla whole body MRI system.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.46.1-46.1
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• 2018

The Fast Imaging Solar Spectrograph (FISS) on the Goode Solar Telescope (GST) at Big Bear Solar Observatory is the imaging Echelle spectrograph developed by the Solar Astronomy Group of Seoul National University and the Solar and Space Weather Group of Korea Astronomy and Space Science Institute. The instrument takes spectral data from a region on the Sun in two spectral bands simultaneously. The imaging is done by the organization of intensity data obtained from the fast raster scan of the slit over the field of view. Since the scan repeats many times, the whole set of data can be used to construct the movies of monochromatic intensity at arbitrary wavelengths within the spectral bands, and those of line-of-sight velocity inferred from different spectral lines. So far there are two standard observing configurations: one recording the $H{\alpha}$ line and the Ca II 8542 line simultaneously, and the other recording the Na I D2 line and Fe I 5435 line simultaneously. We have developed the procedures to produce the standard data for each observing configuration. The procedures include the spatial alignment, the correction of spectral shift of instrumental origin, and the lambdameter measurement of the line wavelength. The standard data include the movie of continuum intensity, the movies of intensity and velocity inferred from a chromospheric spectral line, the movies of intensity and velocity inferred from a photospheric line. The processed standard data will be freely available online (fiss.snu.ac.kr) to be used for research and public outreach. Moreover, the IDL procedures will be provided on request as well so that each researcher can adapt the programs for their own research.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.46-50
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• 2004

Images were acquired by the modulation of terahertz electromagnetic signals and compared by modulation frequencies. For the real-time acquisition of images a fast scanning method has been adopted utilizing a galvanometer. The acquired time domain waveforms were transformed into frequency domain data by fast Fourier transformations (FFT). We chose some frequency components to compare the resolution of images. The beam profiles at the focal position were measured by a knife-edge technique. Beam diameter was shown to decrease as the frequency increased. By scanning one- and two-dimensional samples a significant image enhancement was observed with the frequency increment. A nondesouctive imaging system using ㎔ electromagnetic pulses was also demonstrated.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3216-3218
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• 2000

Projection-type Fast Spin Echo (PFSE) imaging has robustness against motion artifacts due to patient motion during magnetic resonance imaging data acquisition, or reduce flow artifacts. However, it has difficulty in controlling T2 contrast. In this paper, T2 contrast in the PFSE method is analyzed. The contrasts in FSE and PFSE method are compared by computer simulation and experiments with volunteers.

• Journal of Korea Multimedia Society
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• v.12 no.12
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• pp.1701-1709
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• 2009

The mobile terminal system plays a key role in medical industries which require in fast and accurate diagnosis from heterogeneous acquisition equipment. The demand for PACS (picture archiving and communication systems) has continued to increase in major hospitals and private clinics. Patient care depends on how fast the medical imaging system provides images and how accurately the images are interpreted by physicians. In this paper, we propose an efficient method to decipher the hundreds of images required by physicians to accurately diagnose patients. By exploring Motion- JPEG (M-JPEG), this paper has demonstrates the possibilities for efficient management of medical images with a newly designed image file format and improvement in imaging diagnoses through the replaying of moving pictures of a patient in a mobile environment.

• Investigative Magnetic Resonance Imaging
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• v.25 no.2
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• pp.81-92
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• 2021

The role of neuroimaging in patients with acute ischemic stroke has been gradually increasing. The ultimate goal of stroke imaging is to make a streamlined imaging workflow for safe and efficient treatment based on optimized patient selection. In the era of multimodal comprehensive imaging in strokes, imaging based on computed tomography (CT) has been preferred for use in acute ischemic stroke, because, despite the unique strengths of magnetic resonance imaging (MRI), MRI has a longer scan duration than does CT-based imaging. However, recent improvements, such as multicoil technology and novel MRI acceleration techniques, including parallel imaging, simultaneous multi-section imaging, and compressed sensing, highlight the potential of comprehensive MR-based imaging for strokes. In this review, we discuss the role of stroke imaging in acute ischemic stroke management, as well as the strengths and limitations of MR-based imaging. Given these concepts, we review the current MR acceleration techniques that could be applied to stroke imaging and provide an overview of the previous research on each essential sequence: diffusion-weighted imaging, gradient-echo, fluid-attenuated inversion recovery, contrast-enhanced MR angiography, and MR perfusion imaging.