• Investigative Magnetic Resonance Imaging
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• 제17권2호
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• pp.110-122
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• 2013

목적: 발목관절 VISTA 자기공명영상을 이용하여 지방억제를 한 것과 하지 않은 VISTA 사이에서 정량평가를 하며, 발목 인대의 traceability 차이를 알아보고자 하였다. 대상과 방법: SNR의 비교를 위해 팬텀과 한명의 자원자에서 자기공명영상을 촬영하였다. CR (contrast ratio)과 인대 traceability 비교를 위해 발목 관절의 외상 과거력이 없는 10명의 자원자에서 자기공명영상을 촬영하였다. 모든 자기공명영상은 VISTA를 이용하였고 3T에서 촬영하였다. 지방억제는 SPAIR (Spectral Attenuated Inversion Recovery) 기법을 이용하였다. SNR은 피검자가 있을 때와 피검자 없이 촬영한 것으로 구하였다. CR은 열개의 오른쪽 발목관절의 관절액-힘줄, 관절액-연골, 관절액-인대, 지방-힘줄, 지방-연골, 지방-인대의 신호강도를 얻어 구하였다. 두 명의 근골격계 영상의학과 의사가 지방억제를 한 것과 하지 않은 영상을 calcaneofibular ligament (CFL)을 포함한 7개의 발목관절 인대에 대해서 점수를 매겼다 (1, not traceable; 2, barely traceable; 3, adequately traceable; 4, excellently traceable). VISTA 와 VISTA SPAIR 사이에 CR을 비교하는 데는 Wilcoxon signed-rank test를 이용하였다. VISTA 와 VISTA SPAIR사이에 인대 traceability를 비교하는 데에는 Fisher's exact test와 Pearson's chi-squared test를 이용하였다. 결과: 정량평가의 SNR을 보면 지방억제를 하지 않은 영상에 비해 지방억제를 한 자원자의 골수에서 더 낮은 수치를 나타내었다. (7.65 versus [vs.] 36.64). 관절액, 연골, 근육에서는 두 연쇄간에 SNR의 차이가 없었다. 지방억제 VISTA는 관절액-인대 사이 CR만 더 나은 결과를 보여주었지만 (p=0.04) VISTA는 지방-힘줄, 지방-연골, 지방-인대 간에서 모두 더 나은 CR값을 나타내었다(P=0.005). CFL 인대만 통계학적으로 의미 있는 값을 보였는데 지방억제를 하지 않은 VISTA 영상에서 traceability의 값이 더 우세 하였다(p <0.05). 결론: 지방 억제를 한 VISTA와 하지 않은 VISTA에서 유의한 SNR 차이는 골수를 제외하고 없었다. 지방억제를 하지 않은 VISTA에서 CFL을 trace하는데 있어서 더 유리하였다.

• 한국차세대컴퓨팅학회논문지
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• 제15권5호
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• pp.64-74
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• 2019

비강체 정합은 임상적 필요성은 높으나 계산 복잡도가 높고, 정합의 정확성 및 강건성을 확보하기 어려운 분야이다. 본 논문은 비지도 학습 환경에서 3차원 뇌 자기공명 영상 데이터에 딥러닝 네트워크를 이용한 비강체 정합 기법을 제안한다. 서로 다른 환자의 두 영상을 입력받아 네트워크를 통하여 두 영상 간의 특징 벡터를 생성하고, 변위 벡터장을 만들어 기준 영상에 맞추어 다른 쪽 영상을 변형시킨다. 네트워크는 U-Net 형태를 기반으로 설계하여 정합 시 두 영상의 전역적, 지역적인 차이를 모두 고려한 특징 벡터를 만들 수 있고, 손실함수에 균일화 항을 추가하여 3차원 선형보간법 적용 후에 실제 뇌의 움직임과 유사한 변형 결과를 얻을 수 있다. 본 방법은 비지도 학습을 통해 임의의 두 영상만을 입력으로 받아 단일 패스 변형으로 비강체 정합을 수행한다. 이는 반복적인 최적화 과정을 거치는 비학습 기반의 정합 방법들보다 빠르게 수행할 수 있다. 실험은 50명의 뇌를 촬영한 3차원 자기공명 영상을 가지고 수행하였고, 정합 전·후의 Dice Similarity Coefficient 측정 결과 평균 0.690으로 정합 전과 비교하여 약 16% 정도의 유사도 향상을 확인하였다. 또한, 비학습 기반 방법과 비교하여 유사한 성능을 보여주면서 약 10,000배 정도의 속도 향상을 보여주었다. 제안 기법은 다양한 종류의 의료 영상 데이터의 비강체 정합에 활용이 가능하다.

• 한국환경보건학회지
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• 제38권5호
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• pp.380-385
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• 2012

Background: Manganese (Mn) has been found to increase the signal intensity of the globus pallidus (GP) on T1-weighted magnetic resonance images (MRI). We performed this study in order to determine the features of liver disease that correlate with pallidal signal intensities. Methods: We assessed blood Mn levels and pallidal signals in T1-weighted MRI in 49 patients with liver cirrhosis and 23 healthy controls. Results: Increased signal intensity in the GP was observed in 30 of 49 (61.2%) patients with liver cirrhosis, with the pallidal index (PI) in patients with Child-Pugh classes B and C differing significantly from the PI in controls. Multiple linear regression analysis showed that blood Mn concentrations and Child-Pugh scores in cirrhotics were significantly associated with increased PI after controlling for other confounders (p<0.05 each). Conclusions: Pallidal signals on T1-weighted MRI are mainly observed in advanced liver cirrhosis. The present study suggests that advanced liver cirrhosis may be a human model for manganism.

• 대한의생명과학회지
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• 제10권3호
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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.

• 대한물리의학회지
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• 제5권4호
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• pp.615-621
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• 2010

Purpose : The purpose of this study was to compare chronic LBP patients and asymptomatic subjects on measures of multifidus size (cross-sectional area;CSA, thickness) and symmetry (proportional difference of relatively larger side to smaller side). Methods : Data were obtained from 12 asymptomatic subjects without a prior history of LBP (8 females, 4 males), and a retrospective audit was undertaken of records from 12 chronic low back pain patients (8 females, 4 males). CSA and Thickness of the lumbar multifidus muscles was measured from axial T1-weighted magnetic resonance images(MRI). Results : The results of the analysis showed that chronic LBP patients had significantly smaller multifidus CSA and thickness than asymptomatic subjects at L4-5 vertebral levels(p<.05). The asymmetry between sides was seen at L4- L5 vertebral level in patients with chronic low back pain presentations(p<.05). Conclusions : MRI provided a quantitative measure of change between asymptomatic subjects and chronic low back pain patients of multifidus muscle. MRI identified significant differences in cross-sectional area and thickness and helps to evaluate clinically and plan the treatment modalities of LBP.

• Journal of Pharmaceutical Investigation
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• 제31권2호
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• pp.73-80
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• 2001

Lung perfusion scanning, invariably combined with ventilation studies provides a reliable and non-invasive mean to diagnose lung related pathologies despite the availability of modern techniques such as angiography, magnetic resonance imaging, magnetic resonance angiography, and helical (spiral) computed tomography. The technique involves the generation of images by radiations emitted from radioisotopes introduced in to the lungs. Various radiopharmaceuticals have been proposed and designed to incorporate $Tc^{99m}$ in to macroparticulate form for lung perfusion imaging. However, most of these have associated difficulties such as reproducibility of the product with regards to particle size distribution and poor elimination from the lung capillary bed. $Tc^{99m}$ macroaggregated albumin $(Tc^{99m}-MAA)$ is used extensively for clinical lung perfusion imaging and is considered as the radiopharmaceutical of choice. It is non-toxic, safe, and being biodegradable, is easily eliminated from the lung capillary bed by proteolytic enzyme metabolism and by mechanical forces due to lung movement.

• Journal of Korean Neurosurgical Society
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• 제53권2호
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• pp.89-95
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• 2013

Objective : Similar to back pain, neck pain has recently shown to have increasing prevalence. Magnetic resonance imaging (MRI) is useful in identifying the causes of neck pain. However, MRI shows not only pathological lesions but also physiological changes at the same time, and there are few Korean data. The authors have attempted to analyze the prevalence of disc degeneration in highly selective asymptomatic Korean subjects using MRI. Methods : We performed 3 T MRI sagittal scans from C2 to T1 on 102 asymptomatic subjects (50 men and 52 women) who visited our hospital between the ages of 14 and 82 years (mean age 46.3 years). All images were read independently by three observers (two neurosurgeons and one neuroradiologist) who were not given any information about the subjects. We classified grading for cervical disc herniation (HN), annular fissure (AF), and nucleus degeneration (ND), using disc degeneration classification. Results : The prevalence of HN, AF, and ND were 81.0%, 85.9%, and 95.4%, respectively. High prevalence of HN, AF, and ND was shown compared to previous literature. Conclusion : In asymptomatic Korean subjects, the abnormal findings of 3 T MRI showed a high prevalence in HN, AF, and ND. Several factors might play important roles in these results, such as population-specific characters, MRI field strength, and disc degeneration grading system.

• Investigative Magnetic Resonance Imaging
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• 제1권1호
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• pp.75-78
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• 1997

인체의 하지 MR Angiography(MRA)를 위한 하지전용 dual birdcage RF 코일을 설계, 제작하였으며 Volunteer실험을 하여 그 유용성을 보였다. 제안된 코일은 인체의 하지 전체의 영상을 위한 코일로 허벅지로부터 종아리까지 전체를 두 번의 영상을 통해 cover하게 된다. 기존의 방식대로 한 개의 코일을 옮기며 두 번 촬영할 경우 코일을 도중에 옮기게 외어 다리를 움직일 수밖에 없어 두 set의 영상이 완전히 연결이 되지 않지만 제안된 코일의 경우 침대만 움직이게 되므로 이런 문제가 없게 된다. 제안된 코일의 성능은 Volunteer의 하지 MRI 및 MRA를 얻어 확인했으며 임상적으로 매우 유용한 것으로 확인되었다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 추계학술대회
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• pp.78-81
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• 1995

In imaging the samples or human internal organs in a tube shape, general RF-probe types (that encircles a sample or places on top of the sample) are usually unsuitable for the internal imaging due to the degradation of signal-to-noise ratios(SNR's). In the present study the inside-out probes for Magnetic Resonance Imaging (MRI) have been constructed in the three different shapes such as an anti-solenoidal, a saddle and a dual surface types which are positioned as close to the area as possible by putting the probe inside the tubelike sample to improve filling factor. RF-field distributions have also been calculated depending upon the geometrical changes of anti-solenoid probes. Moreover, the performance of the inside-out probes has been checked by measuring SNR's of the images acquired. The inside-out probes constructed in this study produced better SNR's and rf-field uniformity in the area close to the probes in comparing with any other commercial probes. There is a high possibility that the constructed probes in the present study are applicable to the diagnosis of human bodies.

• Journal of Korean Neurosurgical Society
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• 제37권6호
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• pp.427-431
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• 2005

Objective: The purpose of this study is to evaluate the radiological charactersitics related to the formation of peritumoral edema in meningiomas. Methods: Fifty patients with meningioma were examined by magnetic resonance images and cerebral angiography. The predictive factors associated peritumoral edema, such as, tumor size, peritumoral rim (cerebrospinal fluid cleft), shape of tumor margin, signal intensity of tumor in T2WI, and pial blood supply were evaluated. Results: Tumor size, peritumoral rim and pial blood supply correlated with peritumoral edema on univariate analyses. But in multivariate analyses, pial blood supply was statistically significant as a factor for peritumoral edema in meningioma. Conclusion: In our results, pial blood supply is significant contributing factor for peritumoral edema in meningioma.