• Archives of Plastic Surgery
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• v.43 no.5
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• pp.430-437
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• 2016

Background Accurate breast volume assessment is a prerequisite to preoperative planning, as well as intraoperative decision making in breast reconstruction surgery. The use of three-dimensional surface imaging (3D scanning) to assess breast volume has many advantages. However, before employing 3D scanning in the field, the tool's validity should be demonstrated. The purpose of this study was to confirm the validity of 3D-scanning technology for evaluating breast volume. Methods We reviewed the charts of 25 patients who underwent breast reconstruction surgery immediately after total mastectomy. Breast volumes using the Axis Three 3D scanner, water-displacement technique, and magnetic resonance imaging (MRI) were obtained bilaterally in the preoperative period. During the operation, the tissue removed during total mastectomy was weighed and the specimen volume was calculated from the weight. Then, we compared the volume obtained from 3D scanning with those obtained using the water-displacement technique, MRI, and the calculated volume of the tissue removed. Results The intraclass correlation coefficient (ICC) of breast volumes obtained from 3D scanning, as compared to the volumes obtained using the water-displacement technique and specimen weight, demonstrated excellent reliability. The ICC of breast volumes obtained using 3D scanning, as compared to those obtained by MRI, demonstrated substantial reliability. Passing-Bablok regression showed agreement between 3D scanning and the water-displacement technique, and showed a linear association of 3D scanning with MRI and specimen volume, respectively. Conclusions When compared with the classical water-displacement technique and MRI-based volumetry, 3D scanning showed significant reliability and a linear association with the other two methods.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.9
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• pp.1144-1149
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• 2020

The magnetic valve of the breast tissue expander generates imaging artifacts during MRI examination, so MRI examination is limited. To evaluate the effect of imaging artifacts on the diagnosis area for patients with breast tissue expander who need MRI examination. Imaging artifacts were measured using self-made phantoms and actual clinical conditions. Imaging artifacts were measured differently depending on the environment of 1.5 Tesla and 3.0 Tesla, and the effects of imaging artifacts were less in the C-spine and L-spine tests. If MRI due to breast cancer metastasis is absolutely necessary, head & neck examination and L-spine can be examined mainly at 1.5 Tesla, but some sequences may cause distortion due to image artifacts. In terms of safety, MRI scans of patients with breast tissue expanders can be performed conditionally at 1.5T, avoiding 3.0T.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1863-1866
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• 2003

In this study, respiratory motion is modeled by a 2-Dimensional linear expanding-shrinking movement. According to the introduced model, respiratory motion imposes phase error, non-uniform sampling and amplitude modulation distortions on the acquired MRI data. When the motion parameters are known or can be estimated, a reconstruction algorithm based on superposition method was used to removed the MRI artifact. For the purpose of estimating unknown motion parameters, we applied the spectrum shift method to find the respiratory fluctuation function, the x directional expansion coefficient and its center, and also we used the minimum energy method to find the y directional expansion coefficient and its center. The effectiveness of this presented method is shown by Computer simulations.

• Journal of Korean Foot and Ankle Society
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• v.14 no.1
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• pp.53-57
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• 2010

Purpose: This study was designed to evaluate the clinical and radiographical results of anatomical reconstruction by Chen method for chronic lateral ankle instability. Materials and Methods: Fifteen patients with chronic lateral ankle instability who had undergone anatomical reconstruction of anterior talofibular and calcaneofibular ligaments by Chen method were evaluated retrospectively. Average age of the patients was 31.3 years, and average follow-up period was 15.5 months. Preoperative and postoperative radiographs including varus stress view and magnetic resonance imaging (MRI) were analyzed. The clinical evaluation was performed according to the American Orthopaedic Foot and Ankle Society (AOFAS) scale. Results: Radiographically average talar tilt angle was $15.3^{\circ}$ preoperatively, and the difference with contralateral normal side was $10.1^{\circ}$. At last follow up, talar tile angle and the difference with contralateral side improved to $5.9^{\circ}$ and $1.3^{\circ}$ respectively. AOFAS scale was 66.6 preoperatively and 87.3 postoperatively. In MRI findings, four patients had associated intra-articular lesion such as articular cartilage defect, synovitis and osteoarthritis. The talar tilt angle improvement and AOFAS scale of patients without intra-articular lesion was better than those of four patients with intra-articular lesions. Surgical wound pain occurred in six patients and sural neuropathy in three patients. Conclusion: The anatomical reconstruction by Chen method was an easy and effective procedure for symptomatic chronic lateral ankle instability. Careful operative technique may prevent the surgical wound pain and sural neuropathy.

• Proceedings of the KSMRM Conference
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• 2003.10a
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• pp.19-19
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• 2003

목적： MRI 시스템에서 얻어지는 기초 Data는 K-space 즉 촬영대상의 Fourier Transform 된 Data 이다. 이 K-space Data는 영상 촬영 기법에 따라 다른 형식으로 얻어지게 되는데, 이 연구에서는 Radial Imaging에서 Repetition Time 과 Echo Time을 줄이기 위해 구현된 영상기법을 이용하여 얻어진 Data를 이용하여 영상을 재구성하는 방법을 제시하고자 한다.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.67-72
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• 2002

Real-time techniques are motivated by a number of factors including the potential for direct acquisition of diagnostic quality images, facilitation of patient-specific imaging parameters, and reduced examination time. Real-time MRI includes not only a rapid pulse sequence but also high speed image reconstruction and easy interactivity. The frame rate of the real-time technique used should be matched to the physiological timeframes under study. Principal applications thusfar have been in localization, fluoroscopic triggering, guidance of other processes, and potentially in the generation of diagnostic images of moving structures.

• Journal of Korea Multimedia Society
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• v.22 no.12
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• pp.1385-1395
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• 2019

In this paper, we propose a method to fabricate a patient-specific breast implant using MRI images and 3D scan data. Existing breast implants for breast reconstruction surgery are primarily fabricated products for shaping, and among the limited types of implants, products similar to the patient's breast have been used. In fact, the larger the difference between the shape of the breast and the implant, the more frequent the postoperative side effects and the lower the satisfaction. Previous researches on the fabrication of patient-specific breast implants have used limited information based on only MRI images or on only 3D scan data. In this paper, we propose an algorithm for the fabrication of patient-specific breast implants that combines MRI images with 3D scan data, considering anatomical suitability for external shape, volume, and pectoral muscle. Experimental results show that we can produce precise breast implants using the proposed algorithm.

• Journal of Biomedical Engineering Research
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• v.19 no.3
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• pp.243-250
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• 1998

Reconstruction aspects of spiral scan imaging for ultra fast magnetic resonance imagine(MRI) have been investigated with polar and rectangular coordinates-based reconstruction. For the reconstruction of the spiral scan imaging, acquired data in spiral trjectory should be converted to polar or rectangular grids, where interpolation techniques are used. Various reconstruction algorithms for spiral scan imaging are tested, and reconstructed image qualities are compared with computed phantom. An improved reconstruction algorithm with dc-offset correction in projection domain is proposed, which provides the best reconstructed image quality from the simulation. Image artifact with existing algorithms is completely removed with the proposed method.

• Investigative Magnetic Resonance Imaging
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• v.25 no.4
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• pp.293-299
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• 2021

Purpose: To accelerate magnetic resonance fingerprinting (MRF) by developing a flexible deep learning reconstruction method. Materials and Methods: Synthetic data were used to train a deep learning model. The trained model was then applied to MRF for different organs and diseases. Iterative reconstruction was performed outside the deep learning model, allowing a changeable encoding matrix, i.e., with flexibility of choice for image resolution, radiofrequency coil, k-space trajectory, and undersampling mask. In vivo experiments were performed on normal brain and prostate cancer volunteers to demonstrate the model performance and generalizability. Results: In 400-dynamics brain MRF, direct nonuniform Fourier transform caused a slight increase of random fluctuations on the T2 map. These fluctuations were reduced with the proposed method. In prostate MRF, the proposed method suppressed fluctuations on both T1 and T2 maps. Conclusion: The deep learning and iterative MRF reconstruction method described in this study was flexible with different acquisition settings such as radiofrequency coils. It is generalizable for different in vivo applications.

• Journal of the Korean Society of Radiology
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• v.85 no.2
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• pp.345-362
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• 2024

MRI plays an important role in abdominal imaging because of its ability to detect and characterize focal lesions. However, MRI examinations have several challenges, such as comparatively long scan times and motion management through breath-holding maneuvers. Techniques for reducing scan time with acceptable image quality, such as parallel imaging, compressed sensing, and cutting-edge deep learning techniques, have been developed to enable problem-solving strategies. Additionally, free-breathing techniques for dynamic contrast-enhanced imaging, such as extra-dimensional-volumetric interpolated breath-hold examination, golden-angle radial sparse parallel, and liver acceleration volume acquisition Star, can help patients with severe dyspnea or those under sedation to undergo abdominal MRI. We aimed to present various advanced abdominal MRI techniques for reducing the scan time while maintaining image quality and free-breathing techniques for dynamic imaging and illustrate cases using the techniques mentioned above. A review of these advanced techniques can assist in the appropriate interpretation of sequences.