• 한국산학기술학회논문지
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• 제17권3호
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• pp.103-108
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• 2016

본 연구의 목적은 MRI 검사 시 multitransmit 기법의 적용으로 인한 검사시간 단축의 유용성을 알아보고자 하였다. 연구방법은 2015년 7월부터 동년 9월까지 고관절 MRI 검사를 시행한 환자를 대상으로 multitransmit 기법 적용 전-후 고관절의 T1, T2 강조영상을 획득하여 대퇴골두와 장요근의 SNR과 CNR, 그에 따른 검사시간을 비교 평가하였다. 연구결과, multitransmit 기법 적용 전-후 T1, T2 강조영상 모두 SNR과 CNR은 유의한 차이가 없었으며, 검사시간은 적용 전에 비해 T1 강조영상은 42.8%, T2 강조영상은 49.7%로 감소하였다. 결론적으로 MRI 검사 시 본 연구와 같이 multitransmit 기법을 적용하면, 기존의 검사시간 단축관련 연구들에서 문제가 되었던 영상의 질 저하 없이 검사시간을 획기적으로 줄일 수 있으며, 향후 다양한 검사에 multitransmit 기법을 적용한다면 MRI 검사의 고질적 문제인 검사시간을 단축할 수 있어 매우 유용하리라 사료된다.

• 디지털융복합연구
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• 제12권10호
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• pp.385-390
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• 2014

이 연구의 목적은 복부 MRI검사에 유용한 m-DIXON기법이 기존 e-THRIVE기법에 비해 임상적으로 유용한 검사인지 알아보기 위해 2013년 9월부터 2014년 2월까지 간 질환을 주소로 복부 MRI검사를 시행한 84명을 대상으로 분석하였다. 연구결과에서 SNR은 m-DIXON기법 $90.42{\pm}16.90$, e-THRIVE $60.42{\pm}11.54$로 나타났으며, CNR은 m-DIXON기법 $52.38{\pm}22.58$, e-THRIVE기법 $46.31{\pm}20.25$로 나타났다. 정성적 평가는 m-DIXON기법에서 영상의 질 $4.06{\pm}0.34$, 인공물 $3.64{\pm}0.22$, 지방소거 $4.16{\pm}0.15$로 나타났으며, e-THRIVE기법에서 영상의 질 $3.14{\pm}0.35$, 인공물 $3.06{\pm}0.38$, 지방소거 $3.14{\pm}0.30$으로 나타났다. 결론적으로 복부 MRI검사에서 m-DIXON기법은 e-THRIVE 기법에 비해 정량적 평가 및 정성적 평가에서 우수한 것으로 나타나, 향후 복부질환의 진단에 유용하게 활용할 것을 제안한다.

• Investigative Magnetic Resonance Imaging
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• 제11권1호
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• pp.1-9
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• 2007

심장의 영상화에 장애가 되는 요인은 심장 운동, 호흡, 심장 내 혈류 등에 의한 인공물(artifact) 과 심장 조직의 용적이 작음으로 인한 낮은 신호 대 잡음비 등이 있다. 심장 운동에 의한 화질 저하를 막기 위해 신속영상기법(fast imaging technique) 을 이용하여 심장 운동의 특정 위상(phase) 에서만 영상을 얻는 심장동기(cardiac gating) 방법을 이용하고 있다. MRI를 이용한 심장의 검사는 심장의 형태, 심실 기능, 심근 관류, 심근 대사, 관상동맥 영상 등을 대상으로 한다. 심장의 형태적 진단에 있어서 심근내 수분의 정도와 지방조직을 보기 위해 이중(double) 혹은 삼중역전회복기법(triple inversion recovery technique) 을 사용한다. 심근관류검사를 위해서는 조영증강신속경사에코법(contrast-enhanced fast gradient echo technique)을 사용하여 일차통과조영증강(first-pass enhancement) 을 검사한다. 또한 10-15분 지연영상을 얻어 심근내 조영제의 재분포를 검사하여 만성심근경색 등의 심근파괴부위를 확인한다. 심실기능 평가를 위해서는 신속경사에 코법을 이용한 영화영상(cine image) 이 사용되며 심실의 국소적 운동이상 및 심실기능의 정량적 검사가 가능하다. MRI는 관상동맥영상을 제외한 포괄적 심장검사에 실용성이 있다. 특히 지연영상은 다른 검사장비에선 얻을수 없는 유용한 정보이다.

• 대한의용생체공학회:의공학회지
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• 제31권6호
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• pp.464-471
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• 2010

Compressed sensing can be used to reduce scan time or to enhance spatial resolution in MRI. It is now recognized that compressed sensing works well in reconstructing magnitude images if the sampling mask and the sparsifying transform are well chosen. Phase images also play important roles in MRI particularly in chemical shift imaging and magnetic resonance electrical impedance tomography (MREIT). We reconstruct MRI phase images using the compressed sensing technique. Through computer simulation and real MRI experiments, we reconstructed phase images using the compressed sensing technique and we compared them with the ones reconstructed by conventional Fourier reconstruction technique. As compared to conventional Fourier reconstruction with the same number of phase encoding steps, compressed sensing shows better performance in terms of mean squared phase error and edge preservation. We expect compressed sensing can be used to reduce the scan time or to enhance spatial resolution of MREIT.

• Investigative Magnetic Resonance Imaging
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• 제21권2호
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• pp.91-96
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• 2017

Purpose: To describe technical methods for functional magnetic resonance imaging (fMRI) study with arterial spin labeling (ASL) compared to blood oxygenation level-dependent (BOLD) technique and discuss the potential of ASL for research and clinical practice. Materials and Methods: Task-based (n = 1) and resting-state fMRI (rs-fMRI) (n = 20) were performed using ASL and BOLD techniques. Results of both techniques were compared. Results: For task-based fMRI with finger-tapping, the primary motor cortex of the contralateral frontal lobe and the ipsilateral cerebellum were activated by both BOLD and ASL fMRI. For rs-fMRI of sensorimotor network, functional connectivity showed similar results between BOLD and ASL. Conclusion: ASL technique has potential application in clinical and research fields because all brain perfusion imaging, CBF measurement, and rs-fMRI study can be performed in a single acquisition.

• 한국초전도ㆍ저온공학회논문지
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• 제23권4호
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• pp.30-34
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• 2021

Superconducting magnets have paved the way for opening new horizons in designing an electromagnet of a high field magnetic resonance imaging (MRI) device. In the first phase of the superconducting MRI magnet era, low-temperature superconductor (LTS) has played a key role in constructing the main magnet of an MRI device. The highest magnetic resonance (MR) field of 11.7 T was indeed reached using LTS, which is generated by the well-known Iseult project. However, as the limit of current carrying capacity and mechanical robustness under a high field environment is revealed, it is widely believed that commercial LTS wires would be challenging to manufacture a high field (>10 T) MRI magnet. As a result, high-temperature superconductor together with the conducting cooling approach has been spotlighted as a promising alternative to the conventional LTS. In 2020, the Korean government launched a national project to develop an HTS magnet for a high field MRI magnet as an extent of this interest. We have performed a design study of a 7 T 320 mm winding bore HTS MRI magnet, which may be the ultimate goal of this project. Thus, in this paper, design study results are provided. Electromagnetic design and analysis were performed considering the requirements of central magnetic field and spatial field uniformity.

• Journal of Korean Neurosurgical Society
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• 제29권6호
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• pp.810-814
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• 2000

We report two cases of spinal subdural hematoma in the lumbar region after trauma. They developed in a 27-years old man and a 32-year-old woman. They had no other causes such as bleeding tendency, preexisting spinal lesions, lumbar puncture, vascular malformation and anticoagulant therapy. There lesions were diagnosed with MRI(fat suppression) and treated by lumbar puncture.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.129-130
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• 2008

• Neonatal Medicine
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• 제28권3호
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• pp.108-115
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• 2021

Purpose: Magnetic resonance imaging (MRI) is a useful tool for evaluating brain injury and maturation in preterm infants and often requires sedation to acquire images of sufficient quality. Infant sedation is often associated with adverse events, despite extreme precautions. In this study, the swaddling technique was investigated as an alternative non-pharmacological strategy to obtain brain MRIs of sufficient quality. Methods: We applied the feed and swaddle technique during routine brain MRI as a quality improvement project and compared its morbidity with that of sedation in a historic age-matched group. Seventy-nine very low birth weight infants in the neonatal intensive care unit of Ajou University Hospital (Suwon, Korea) were enrolled. Thirty-two (40.5%) infants were in the feed and swaddling group, and 47 (59.5%) were in the sedation group. Results: The morbidity associated with the cardiopulmonary system (swaddling group vs. sedation group: 53.13% [n=17] vs. 63.83% [n=30], P=0.723) and central nervous system (40.63% [n=13] vs. 29.79% [n=14], P=0.217) were not significantly different between groups. The MRI failure rate was not significantly different (swaddling group vs. sedation group: 12.5% [n=4] vs. 4.3% [n=2], P=0.174). The MRI scanning time was longer in the swaddling group than in the sedation group (76.5±20.3 minutes vs. 61.5±13.6 minutes, P=0.001). Cardiopulmonary adverse events were significantly less common in the swaddling group than in the sedation group (3.13% [n=1] vs. 34.04% [n=16], P=0.002). Conclusion: The success rate of MRI was comparable between the swaddling technique and sedation. Furthermore, despite the drawback of prolonged scan time, cardiopulmonary adverse events are fewer with swaddling than with sedative agents. Therefore, swaddling can be an alternative to sedation or anesthesia when performing neonatal MRI scans.

• Archives of Plastic Surgery
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• 제43권5호
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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.