• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.111-111
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• 2001

목적： To evaluate the feasibility of the event-related functional MR study using power grip studying the hand motor system 대상 및 방법： Event-related functional MRI was performed on a 1.5T MR unit in seven norm volunteers (man=7, right-handedness=2, left-handedness=5, mean age： 25 years). A single-shot GRE-EPI sequence (TR/TE/flip angle： 1000ms/40ms/90, FOV = 240 mm matrix= 64$\times$64, slice thickness/gap = 5mm/0mm, 7 true axial slices) was used for functiona MR images. A flow-sensitive conventional gradient echo sequence (TR/TE/flip angl 50ms/4ms/60) was used for high-resolution anatomical images. To minimize the gross hea motion, neck-holders (MJ-200, USA) were used. A series of MR images were obtained in axial planes covering motor areas. To exclude motion-corrupted images, all MR images wer surveyed in a movie procedure and evaluated using the estimation of center of mass of ima signal intensities. Power grip task consisted of the powerful grip of all right fingers and hand movement ta used very fast right finger tapping at a speed of 3 per 1 second. All tasks were visual-guid by LCD projector (SHARP, Japan). Two tasks consisted of 134 phases including 7 activatio and 8 rest periods. Active stimulations were performed during 2 seconds and rest period were 15 seconds and total scan time per one task was 2 min 14 sec. Statistical maps we obtained using cross-correlation method. Reference vector was time-shifted by 4 seconds an Gaussian convolution with a FWHM of 4 seconds was applied to it. The threshold in p val for the activation sites was set to be 0.001. All mapping procedures were peformed usin homemade program an IDL (Research Systems Inc., USA) platform. We evaluated the activation patterns of the motor system of power grip compared to hand movement in t event-related functional MRI.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.155-156
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• 1996

The intercommissural(AC-PC) line is automatically detected for HR and PET images. With the detected AC-PC lines from MR and PET images, fully non-iterative automatic co- registration is accomplished. It provides a new automated method for image co-registration.

• Investigative Magnetic Resonance Imaging
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• v.25 no.4
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• pp.300-312
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• 2021

Compressed sensing (CS) has been investigated in magnetic resonance (MR) parametric mapping to reduce scan time. However, the relatively long reconstruction time restricts its widespread applications in the clinic. Recently, deep learning-based methods have shown great potential in accelerating reconstruction time and improving imaging quality in fast MR imaging, although their adaptation to parametric mapping is still in an early stage. In this paper, we proposed a novel deep learning-based framework DEMO for fast and robust MR parametric mapping. Different from current deep learning-based methods, DEMO trains the network in an unsupervised way, which is more practical given that it is difficult to acquire large fully sampled training data of parametric-weighted images. Specifically, a CS-based loss function is used in DEMO to avoid the necessity of using fully sampled k-space data as the label, thus making it an unsupervised learning approach. DEMO reconstructs parametric weighted images and generates a parametric map simultaneously by unrolling an interaction approach in conventional fast MR parametric mapping, which enables multi-tasking learning. Experimental results showed promising performance of the proposed DEMO framework in quantitative MR T1ρ mapping.

• The KIPS Transactions:PartB
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• v.10B no.3
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• pp.339-346
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• 2003

In this paper, we propose a new method in which interpolation images are created by using a small number of axiai T2-weighted images instead of using many sectional images for 3D visualization of brain MR images. For image Interpolation, an important part of this process, we first segment a region of interest (ROI) that we wish to apply 3D reconstruction and extract the boundaries of segmented ROIs and MBR information. After the image size of interpolation layer is determined according to the changing rate of MBR size between top slice and bottom slice of segmented ROI, we find the corresponding pixels in segmented ROI images. Then we calculate a pixel's intensity of interpolation image by assigning to each pixel intensity weights detected by cube interpolation method. Finally, 3D reconstruction is accomplished by exploiting feature points and 3D voxels in the created interpolation images.

• Investigative Magnetic Resonance Imaging
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• v.3 no.1
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• pp.73-77
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• 1999

Purpose : The purpose of the study was to evaluate the sensitivity and specificity of proton-weighted fast spin-echo MR imaging in diagnosing the meniscal tear of knee as an reasonable substitute for conventional spin-echo imaging. Materials and Methods : 102 consecutive patients, proved by surgery, proved by surgery, were participated in this study. All of them were suspected internal derangement of knee, examined by fast spin-echo MR imaging including sagittal and coronal images on a 1.5T MR imager and underwent arthroscopic or open surgery of knee joint within 2 months. These images were reviewed retrospectively by three radiologists. The sensitivity and specificity of meniscal tear were calculated. Results : The sensitivity and specificity of meniscal tear using proton-weighted fast spin-echo MR imaging were 94%, 93% inmedialmeniscus and 92%, 88% in lateral meniscus. Conclusion : The sensitivity and specificity of meniscal tear using proton weighted fast-spin echo MR images were as high as those using conventional spin-echo images. The proton-weighted fast-spin echo MR imaging can be an alternative to conventional spin-echo MR imaging in diagnosing meniscal tear of the knee.

• Journal of Korea Multimedia Society
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• v.13 no.11
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• pp.1698-1705
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• 2010

In this paper, we propose a fast liver segmentation method from magnetic resonance(MR) images. Our method efficiently divides a MR image into a set of discrete objects, and boundaries based on the normalized gradient magnitude information. Then, the objects belonging to the liver are detected by using 2D seeded region growing with seed points, which are extracted from the segmented liver region of the slice immediately above or below the current slice. Finally, rolling ball algorithm, and connected component analysis minimizes false positive error near the liver boundaries. Our method was validated by twenty data sets and the results were compared with the manually segmented result. The average volumetric overlap error was 5.2%, and average absolute volumetric measurement error was 1.9%. The average processing time for segmenting one data set was about three seconds. Our method could be used for computer-aided liver diagnosis, which requires a fast and accurate segmentation of liver.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.5
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• pp.1-7
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• 2009

In recent years, compressed sensing (CS) algorithm has been studied in various research areas including medical imaging. To use the CS algorithm, the signal that is to be reconstructed needs to have the property of sparsity But, most medical images generally don't have this property. One method to overcome this problem is by using sparsifying transform. However, MR imaging, compared to other medical imaging modality, has the unique property that by using appropriate image acquisition pulse sequences, the image contrast can be modified. In this paper, we propose the possibility of applying the CS algorithm with non-sparsifying transform to the pulse sequence modified MR images and improve the reconstruction performance of the CS algorithm by using an appropriate sparsifying transform. We verified the proposed contents by computer simulation using Shepp-Logan phantom and in vivo data.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.130-130
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• 2002

Purpose： To evaluate the liver enhancement pattern of MR images obtained after administration of manganese phthalocyanine (MnPC), which is a newly developed macromolecular MR contrast agent, In experimentally implanted VX2 tumor of rabbits and compare with G4-DTPA and Mn-DPDP.

• Journal of Korean Neurosurgical Society
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• v.38 no.5
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• pp.355-358
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• 2005

Objective : The purpose of this study is to analyze the patterns of intervertebral disc enhancement seen in infectious spondylitis, differentiate between two groups[tuberculous vs pyogenic spondylitis]. Methods : Between January 1994 and December 2002, 83patients underwent operative procedure with confirmed to histopathologic evaluation. Magnetic resonance[MR] images were obtained in all patients and were analyzed retrospectively. 57patients had tuberculosis and 26patients were infected by pyogens. The patterns of gadolinium enhancement of disc were classified into 4 types[post's classification] : Type I, non-enhancing; Type II, enhancement of the peripheral rim; Type III, Type II with central area and partial endplate; Type IV, general enhancement. Results : The enhancement patterns observed were as follows : Common pattern of tuberculous spondylitis was Type II, and pyogenic spondylitis was Type III. [p < 0.01] This difference may result from pathophysiologic varieties of organisms. Conclusion : Careful preoperative MR analysis of the patterns of disc enhancement occuring in infectious spondylitis can be useful for differentiating between the tuberculous and pyogenic spondylitis.

• Journal of Veterinary Clinics
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• v.25 no.3
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• pp.176-181
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• 2008

Fluid accumulation within the tympanic bulla is an important diagnostic indicator of canine otitis media although its identification can be a challenge using currently available imaging techniques. The purpose of this study was to compare radiography, computed tomography (CT) and magnetic resonance imaging (MRI) in the identification of fluid accumulation within canine tympanic bulla. Unilateral tympanic bulla in 10 beagles were experimentally filled with blood or saline. Quantitative analysis of CT images were obtained by using Hounsfield unit (HU). MR signal intensity was obtained by using region of interesting (ROI) and compared with those of gray matter. On the CT image, the presence of blood or saline produced a fluid opacity occupying the tympanic bulla. On the MR image, the appearance of blood in the tympanic bulla was isointense in T1-weighted images and hyperintense in T2-weighted images. However, the appearance of saline in the tympanic bulla was hypointense in T1-weighted images and hyperintense in T2-weighted images. This study suggest that CT and MR imaging are useful methods for detection and differentiation of fluid in canine tympanic bulla.