• Investigative Magnetic Resonance Imaging
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• 제14권1호
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• pp.10-20
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• 2010

목적: 최근, 미국 애리조나 세도나에서 열린 국제자기공명학회 (ISMRM) 주관의 2009년 데이터 샘플링과 영상 복원에 관한 워크샵에서 자기공명영상 복원 대회가 열렸다. 이 대회는 time resolved contrast enhanced MR angiography 에 대한 고속 촬영의 실제 활용 가능성을 평가하기 위한 것이었다. 본 논문은 이 대회의 우승 결과를 얻은 k-t FOCUSS 알고리듬을 단계별로 자세히 묘사하도록 한다. 대상 및 방법: 본 그룹은 앞선 연구에서 비교적 덜 스파스한 심장 영상에 대해 k-t FOCUSS 알고리듬이 성공적으로 압축센싱 문제를 풀수 있음을 증명했다. 따라서 k-t FOCUSS 알고리듬을 time resolved contrast enhanced MR angiography 에 적용함으로써, 매우 정확한 영상 복원이 가능할 것이다. 영상 복원을 위해 X-ray 대뇌 혈관조영 영상으로부터 구성된 다운 샘플링된 데이터가 대회 주최측으로부터 공통으로 제시되었고, 방사선과 의사들이 각 복원된 영상에 대한 사전 정보 없이, 원래 영상과 복원된 결과를 비교함으로써, 영상의 질을 평가하였다. 결과: 다양한 다운샘플링에 대해 얻어진 결과들은 영상의 스파스 변환이나 샘플링 형태와 같은 압축센싱의 중요한 요소들에 의해 크게 영향을 받는다는 것을 보여주었다. 결론: 복원된 결과로부터, 압축센싱 동적자기공명영상 기법인 k-t FOCUSS 가 고해상도의 time resolved contrast enhanced MR angiography 를 가능하게 할 수 있음을 확인하였다.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2002년도 제7차 학술대회 초록집
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• pp.117-122
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• 2002

Contrast-enhanced MR angiography has become a widely used method useful for clinical diagnosis. Early studies identified a number of technical issues, and many of these have been addressed with various MRI physics innovations over the last several years. The quality of the results is high enough that CE MRA is replacing conventional x-ray angiography methods at many institutions. Ongoing research is expected to provide further improvements in performance, most notably in additional reductions in examination time, in time-resolved 3D imaging, and in improved imaging of the peripheral vasculature with extended fields of view.

• Korean Journal of Radiology
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• 제1권2호
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• pp.91-97
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• 2000

Objective: To determine whether the time-intensity curves acquired by test and main dose contrast injections for MR angiography are similar. Materials and Methods: In 11 patients, repeated contrast-enhanced 2D-turbo-FLASH scans with 1-sec interval were obtained. Both test and main dose timeintensity curves were acquired from the abdominal aorta, and the parameters of time-intensity curves for the test and main boluses were compared. The parameters used were arterial and venous enhancement times, arterial peak enhancement time, arteriovenous circulation time, enhancement duration and enhancement expansion ratio. Results: Between the main and test boluses, arterial and venous enhancement times and arteriovenous circulation time showed statistically significant correlation (p < 0.01), with correlation coefficients of 0.95, 0.92 and 0.98 respectively. Although the enhancement duration was definitely greater than infusion time, reasonable measurement of the end enhancement point in the main bolus was impossible. Conclusion: Only arterial and venous enhancement times and arteriovenous circulation time of the main bolus could be predicted from the test-bolus results. The use of these reliable parameters would lead to improvements in the scan timing method for MR angiography.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2001년도 제6차 학술대회 초록집
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• pp.136-136
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• 2001

Purpose： Subclavian steal refers to the retrograde flow of blood in a vertebral artery that supplies t ipsilateral shoulder and arm caused by proximal subclavian artery stenosis or occlusion. T purpose of this exhibit is to demonstrate MR findings of subclavian steal on contrast-enhanc 3D (CE 3DMRA) and 2D TOF MR angiography. Method： Four patients(men 3 and women 1, age： 28-78years) with subclavian steal obtained both CE 3DMRA and digital subtraction angiography(DSA) including subclavian arterie Sequential imaging was undertaken during first pass after double dose of Gd-DTPA (0 mM/kg) Injected by a power injector. Coronal source images were obtained with coronal D-fast low angle shot sequence(TR/TE/flip angle=3.8/l.3/35, acquisition time= 10sec/one measurement). Precontrast imaging was subtracted from enhanced images and maximu intensity projection was done. 2D time-of-flight MR angiography(2D TOF) of the carot bifurcation was added in all cases with post-saturation. All studies were review retrospectively.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 1999년도 제4차 추계학술대회 초록집
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• pp.44-44
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• 1999

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2004년도 제9차 학술대회 초록집
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• pp.44-44
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• 2004

• Korean Journal of Radiology
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• 제1권3호
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• pp.142-151
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• 2000

Objective: To determine the optimal scan timing for contrast-enhanced magnetic resonance angiography and to evaluate a new timing method based on the arteriovenous circulation time. Materials and Methods: Eighty-nine contrast-enhanced magnetic resonance angiographic examinations were performed mainly in the extremities. A 1.5T scanner with a 3-D turbo-FLASH sequence was used, and during each study, two consecutive arterial phases and one venous phase were acquired. Scan delay time was calculated from the time-intensity curve by the traditional (n = 48) and/or the new (n = 41) method. This latter was based on arteriovenous circulation time rather than peak arterial enhancement time, as used in the traditional method. The numbers of first-phase images showing a properly enhanced arterial phase were compared between the two methods. Results: Mean scan delay time was 5.4 sec longer with the new method than with the traditional. Properly enhanced first-phase images were found in 65% of cases (31/48) using the traditional timing method, and 95% (39/41) using the new method. When cases in which there was mismatch between the target vessel and the time-intensity curve acquisition site are excluded, erroneous acquisition occurred in seven cases with the traditional method, but in none with the new method. Conclusion: The calculation of scan delay time on the basis of arteriovenous circulation time provides better timing for arterial phase acquisition than the traditional method.

• Korean Journal of Radiology
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• 제1권4호
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• pp.185-190
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• 2000

Objective: To document the imaging findings of hepatic cavernous hemangioma detected in cirrhotic liver. Materials and Methods: The imaging findings of 14 hepatic cavernous hemangiomas in ten patients with liver cirrhosis were retrospectively analyzed. A diagnosis of hepatic cavernous hemangioma was based on the findings of two or more of the following imaging studies: MR, including contrast-enhanced dynamic imaging (n = 10), dynamic CT (n = 4), hepatic arteriography (n = 9), and US (n = 10). Results: The mean size of the 14 hepatic hemangiomas was 0.9 (range, 0.5-1.5) cm in the longest dimension. In 11 of these (79%), contrast-enhanced dynamic CT and MR imaging showed rapid contrast enhancement of the entire lesion during the early phase, and hepatic arteriography revealed globular enhancement and rapid filling-in. On contrast-enhanced MR images, three lesions (21%) showed partial enhancement until the 5-min delayed phases. US indicated that while three slowly enhancing lesions were homogeneously hyperechoic, 9 (82%) of 11 showing rapid enhancement were not delineated. Conclusion: The majority of hepatic cavernous hemangiomas detected in cirrhotic liver are small in size, and in many, hepatic arteriography and/or contrast-enhanced dynamic CT and MR imaging demonstrates rapid enhancement. US, however, fails to distinguish a lesion of this kind from its cirrhotic background.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회.한국자기공명학회 2005년도 공동학술대회
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• pp.31-31
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• 2005

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 1997년도 제2차 추계학술대회 초록집
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• pp.19-19
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• 1997