• Journal of Korean Neurosurgical Society
• /
• 제37권6호
• /
• pp.453-455
• /
• 2005

Two young women were brought to the Emergency room with generalized tonic and clonic seizures. Seizure developed seven and ten days after delivery respectively without the clinical signs of pre-eclampsia throughout the pregnancies. Magnetic resonance(MR) image of the brain showed characteristically symmetrical abnormal signals in the parietal and occipital regions. After several days of medical treatment, they were discharged without neurologic sequelae and follow-up MR images taken three months after discharge showed complete disappearance of the previous abnormal signals.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
• /
• pp.70-72
• /
• 2007

In this study, electromagnetic fields emitted from the various environment in the hospital were measured. Measurement spot was patients' head. To monitor how much magnetic fields are emitting from operation room, monitoring device was attached to 19 anesthesiologist and monitoring lasted 8 hours. We also took a measurement from various medical devices. Devices include ESWL, PET, MRI, CT, Gamma knife, X-ray, Angiogram, Echocardiogram, Upper GI and Linear Accelerator. Electromagnetic fields were measured from 10 spots from each of 5 patient waiting room. As a results, there were no places showing risk of high exposure. All the measurement values were below the reference levels for general public exposure to time varying electric and magnetic fields which is issued by ICNIRP.

• Journal of Korean Neurosurgical Society
• /
• 제63권2호
• /
• pp.188-201
• /
• 2020

Objective : The purpose of this study was to suggest that computed tomography angiography (CTA) is valuable as the only preliminary examination for mechanical thrombectomy (MT). MT after single examination of CTA including noncontrast computed tomography (NCCT) and maximum intensity projection (MIP) improves door-to-puncture time as well as results in favorable outcomes. Methods : A total of 157 patients who underwent MT at Dong Kang Medical Center from April 2015 to March 2019 were divided into two groups based on the examination performed prior to MT : CTA group who underwent CTA with NCCT and MIP, and NCCT+magnetic resonance image (MRi) group who underwent MRI including perfusion images after NCCT. In the two groups, time to CTA imaging or NCCT+MRi imaging after symptom onset, and time to arterial puncture and reperfusion were characterized as time-related outcomes. The evaluation of vascular recanalization after MT was defined as a modified thrombolysis in cerebral infarction (mTICI) scale. National Institutes of Health Stroke Scale (NIHSS) was assessed at the time of the visit to the emergency room and modified Rankin Scale (mRS) was assessed after 90 days. Results : Typically, there were 34 patients in the CTA group and 33 patients in the NCCT+MRi group. A significantly shorter delay for door-to-puncture time was observed (mean, 86±22.1 vs. 176±47.5 minutes; <0.01). Also, a significantly shorter door-to-imege time in the CTA group was observed (mean, 13±6.8 vs. 93±30.8 minutes; p<0.01). Moreover, a significantly shorter onset-to-puncture time was observed (mean, 195±128.0 vs. 314±157.6 minutes; p<0.01). Reperfusion result of mTICI ≥2b was 100% (34/34) in the CTA group and 94% (31/33) in the NCCT+MRi group, and mTICI 3 in 74% (25/34) in the CTA group and 73% (24/33) in the NCCT+MRi group. Favorable functional outcomes (mRS score ≤2 at 90 days) were 68% (23/34) in the CTA group and 60% (20/33) in the NCCT+MRi group. Conclusion : A single-phase CTA including NCCT and MIP images was performed as a single preliminary examination, which led to a reduction in the time of the procedure and resulted in good results of prognosis. Consequently, it is concluded that this method is of sufficient value as the only preliminary examination for decision making.

• 대한임상검사과학회지
• /
• 제37권2호
• /
• pp.123-128
• /
• 2005

Magnetoencephalography (MEG) is the measurement of the magnetic fields produced by electrical activity in the brain, usually conducted externally, using extremely sensitive devices such as Superconducting Quantum Interference Device (SQUID). MEG needs complex and expensive measurement settings. Because the magnetic signals emitted by the brain are on the order of a few femtoteslas (1 fT = 10-15T), shielding from external magnetic signals, including the Earth's magnetic field, is necessary. An appropriate magnetically shielded room is very expensive, and constitutes the bulk of the expense of an MEG system. MEG is a relatively new technique that promises good spatial resolution and extremely high temporal resolution, thus complementing other brain activity measurement techniques such as electroencephalography (EEG), positron emission tomography (PET), single-photon emission computed tomography (SPECT) and functional magnetic resonance imaging (fMRI). MEG combines functional information from magnetic field recordings with structural information from MRI. The clinical uses of MEG are in detecting and localizing epileptic form spiking activity in patients with epilepsy, and in localizing eloquent cortex for surgical planning in patients with brain tumors. Magnetoencephalography may be used alone or together with electroencephalography, for the measurement of spontaneous or evoked activity, and for research or clinical purposes.

• Journal of Trauma and Injury
• /
• 제32권2호
• /
• pp.80-85
• /
• 2019

Purpose: To compare the time intervals to magnetic resonance imaging (MRI) and surgical treatment in patients having traumatic cervical spinal cord injury (SCI) with and without bony lesions. Methods: Retrospectively analyzed adult patients visited Kyungpook National University Hospital and underwent surgical treatment for cervical SCI within 24 hours. The patients who were suspected of having cervical SCI underwent plain radiography and computed tomography (CT) upon arrival. After the initial evaluation, we evaluated the MRI findings to determine surgical treatment. Waiting times for MRI and surgery were evaluated. Results: Thirty-four patients were included. Patients' mean age was 57 (range, 23-80) years. Patients with definite bony lesions were classified into group A, and 10 cases were identified (fracture-dislocation, seven; fracture alone, three). Patients without bony lesions were classified into group B, and 24 cases were identified (ossification of the posterior longitudinal ligament, 16; cervical spondylotic myelopathy, eight). Mean intervals between emergency room arrival and start of MRI were 93.60 (${\pm}60.08$) minutes in group A and 313.75 (${\pm}264.89$) minutes in group B, and the interval was significantly shorter in group A than in group B (p=0.01). The mean times to surgery were 248.4 (${\pm}76.03$) minutes in group A and 560.5 (${\pm}372.56$) minutes in group B, and the difference was statistically significant (p=0.001). The American Spinal Injury Association scale at the time of arrival showed that group A had a relatively severe neurologic deficit compared with group B (p=0.046). There was no statistical significance, but it seems to be good neurological recovery, if we start treatment sooner among patients treated within 24 hours (p=0.198). Conclusions: If fracture or dislocation is detected by CT, cervical SCI can be easily predicted resulting in MRI and surgical treatment being performed more rapidly. Additionally, fracture or dislocation tends to cause more severe neurological damage, so it is assumed that rapid diagnosis and treatment are possible.

• Investigative Magnetic Resonance Imaging
• /
• 제4권2호
• /
• pp.113-119
• /
• 2000

목적 : 산소호흡을 이용한 뇌의 관류 자기공명영상의 임상적용 가능성을 알고자 하였다. 대상 및 방법 정상 성인 지원자 2명과 3명의 환자, 각각 모야모야병 환자 1명, 뇌경색환자 1명, 뇌수막종 환자 1명을 대상으로 하였으며, 1.5 Tesla의 자기공명영상 장치를 이용하여 뇌의 자화율 대조 (susceptibility contrast) echo planar image (EPI) 방법으로 뇌영역을 10 slice씩 25회(검사시간은 검사당 1.6초) 영상을 얻었다. 검사자는 안면마스크를 착용한 상태로 스캔 시작 8초 후부터 35초가지 산소 15 liter/min를 실내 공기와 혼합되어 흡입되도록 하였다. 획득된 영상을 Magnetom Vision (Siemens Medical Systems, Erlangen, Germany)의 VB31C 프로그램을 이용하여 산소투여전(3골 번째 검사)과, 산소투여 후의 초기 (12-18 번째 검사)와 후기(19-25 번째 검사) 군으로 나누었다. 초기 및 후기 군과 산소투여전 군의 신호차이는 Z-score 0.7 내지 1.0으로 하여 여러번 영상후 처리를 반복하여 difference map을 얻어서, T1 강조영상에 중첩시켜 관류 영상을 얻었다. 모야모야병 환자는 추가로 Gd-DTPA를 0.1 mmol/kg급속주사 후 동일한 방법으로 관류 영상을 얻어 산소호흡에 의한 관류 영상과 비교하였다. 결과 : 산소 공급 후에 시행한 자화율 대조 EPI 방법으로 2명의 지원자와 각각 1예의 모야모야병, 뇌경색, 뇌수막종 증례에서 혈류 분포를 반영하는 관류 영상을 얻을 수 있었다. 모야모야병 1예의 산소 호흡에 의한 관류 영상은 Gd-DTPA투여후의 관류 영상과 유사한 양상을 보였다. 결론 : 산소호흡을 이용한 자화율 대조 EPI 방법은 향후 뇌의 관류 자기공명영상 방법으로 적용이 가능하리라고 생각된다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집C
• /
• pp.482-484
• /
• 2001

In orthopedics, hip arthroplasty is the operation that replaces damaged hip joint to artificial joint. In hip arthroplasty, quite better result can be achieved if robot is applied to machine cavity in bone, especially when cementless stem is used. So several kinds of robots were introduced for hip arthroplasty, but they used MRI, CT Scan, vision analysis and real time tracking of bone position for registration of robot. To overcome shortage of conventional robot surgery, gauge based registration method was proposed and small robot was designed. In this method, small robot is mounted on femur, and its position is determined by gauge registration method. Operation procedure was performed on model femur and result was analyzed. This robotic hip surgery system is expected to more adaptable in operation room.

• Composites Research
• /
• 제12권6호
• /
• pp.22-30
• /
• 1999

$Nb_3Sn$ 복합초전도 테이프는 금속간 화합물로서 다른 초전도 재료에 비하여 임계밀도가 높아 MRI등에 널리 이용되고 있다. 한편 $Nb_3Sn$층은 화합물이므로 bending이나 winding등의 코아 제작시 테이프 도체에 응력이 작용하면 화합물층에 취성으로 인한 크랙이 발생하여 부분적으로 파단이 일어나 임계전류 특성이 열화하며 무응력 상태에 비하여 크게 저하된다. 따라서 이와 같은 $Nb_3Sn$복합초전도 테이프의 실질적인 적용을 위해서는 선재의 제조과정 뿐만 아니라 가동 중에 기계적 응력에 대한$Nb_3Sn$복합 초전도 테이프의 미시적 거동 특성을 필히 이해하여야 할 필요가 있다. 본 연구에서는 음향방출기법(Acoustic Emission)을 이용하여 $Nb_3Sn$ 복합초전도 테이프에 대해서 일정변형속도(constant extension rate)제어로 인장하중이 작용할 경우 발생하는 AE 신호특성과 이에 대응하는 각 화합물층의 미시적 변형거동 특성과의 상관관계를 분석하였다.

• 한국콘텐츠학회논문지
• /
• 제16권8호
• /
• pp.419-426
• /
• 2016

본 연구는 PET-MRI를 다루는 방사선 작업 종사자들의 효과적인 피폭관리와 경과시간(24시간, 1주, 2주, 3주, 4주) 및 자기장에 따른 개인피폭선량계의 변화를 분석하고자 하였다. 그룹화된 TLD에 열처리 수행 및 방사선을 조사하여 각기 다른 노출 환경에 보관한 후 실험이 종료되면 판독을 수행하여 글로우 곡선 및 피폭 방사선량의 변화 추이를 관찰하였다. 그 결과, 24시간 경과한 TLD 그룹에서 글로우 곡선 및 방사선량의 차이가 있는 것으로 확인되었다. 이는 자기장 노출로 인한 변화인 것으로 해석할 수 있다. 또한 자기장에 노출되지 않은 TLD 그룹의 평균 피폭 방사선량은 15.41 mSv로 나타났으며, 자기장에 노출된 TLD 그룹의 평균 피폭 방사선량은 14.83 mSv로 나머지 그룹보다 가장 크게 감소(3.80%)하는 경향을 나타냈다. PET-MRI실에서 근무하는 방사선 작업 종사자가 개인피폭선량계로 TLD를 사용하는 경우, 정기 판독주기에 맞게 TLD 판독 시 자기장 노출로 인한 실제 피폭 방사선량과의 차이는 크게 없을 것으로 판단되어지나 정기 판독이 아닌 중간 판독을 수행하였을 경우, 실제 피폭 방사선량보다 낮은 피폭선량 값을 나타낼 것이다.

• 소성∙가공
• /
• 제31권3호
• /
• pp.124-128
• /
• 2022

NdFeB magnets have been positioned as the core materials in advanced technologies such as MRI (magnetic resonance imaging), FA (factory automation system), robot, motors, and so on based on the highest magnetic properties. To effectively improve the refined microstructure, the plastic deformation has been known as the good alternatives by the recrystallization. However, it has been regarded as being impossible because of the few slip systems in the RE-Fe-B magnets at room temperature. The purpose of this study was to investigate the possibility of control of grain refinement and magnetic anisotropy of NdFeB alloy powder by the severe plastic deformation. The NdFeB magnet powder was fabricated by gas atomization process, and the powder was pre-compacted at high temperature. The pre-compacted billets were deformed by HPT (high pressure torsion), and then the deformed billets were observed microstructure and magnetic properties. After the HPT process at room temperature, the grain size decreased with increasing because of the melted Nd-rich phase, and the anisotropy of Nd₂Fe₁₄B phase was formed after the HPT process.