• 대한방사성의약품학회지
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• 제1권2호
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• pp.130-136
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• 2015

We evaluate the influence of MR contrast agent on positron emission tomography (PET) image using phantom, animal and human studies. Phantom consisted of 15 solutions with the mixture of various concentrations of Gd-based MR contrast agent and fixed activity of [$^{18}F$]FDG. Animal study was performed using rabbit and two kinds of MR contrast agents. After injecting contrast agent, CT or MRI scanning was performed at 1, 2, 5, 10, and 20 minutes. PET image was obtained using clinical PET/CT scan, and attenuation correction was performed using the all CT images. The values of HU, PET activity and MRI intensity were obtained from ROIs in each phantom and organ regions. In clinical study, patients (n=20) with breast cancer underwent sequential acquisitions of early [$^{18}F$]FDG PET/CT, MRI and delayed PET/CT. In phantom study, as the concentration increased, the CT attenuation and PET activity also increased. However, there was no relationship between the PET activity and the concentration in the clinical dose range of contrast agent. In animal study, change of PET activity was not significant at all time point of CT scan both MR contrast agents. There was no significant change of HU between early and delayed CT, except for kidney. Early and delayed SUV in tumor and liver showed significant increase and decrease, respectively (P<0.05). Under the condition of most clinical study (< 0.2 mM), MR contrast agent did not influence on PET image quantitation.

• 대한방사선기술학회지:방사선기술과학
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• 제41권2호
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• pp.103-107
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• 2018

In MR, the iodine CT contrast medium reduces the T1 and T2 relaxation times of the substance, resulting in a change in signal intensity. This study aimed to measure the relaxation rate of MR contrast medium with or without diluting CT contrast medium and analyzed the effect of CT contrast medium. Undiluted Gadoteridol solution was diluted with saline to prepare MR contrast medium phantoms with various levels of Gadoteridol concentrations. Moreover, undiluted Iomeprol was mixed with the prepared MR contrast medium phantoms at 1:1 ratio to make MR contrast medium phantoms with containing CT contrast medium for the experiment. T1 and T2 mappings were conducted to quantitatively evaluate the relaxation time and relaxation rate of these phantoms. The results showed that the T1 and T2 relaxation time and relaxation rate of MR contrast medium diluted with CT contrast medium were significantly (p<0.05) shorter than those of MR contrast medium not diluted with CT contrast medium. The results of this study imply that, when MR contrast medium shall be used after injecting CT contrast medium, CT contrast medium should be discharged enough. Moreover, it would be desirable to conduct CT test after taking MRI test in order to reduce the effects of CT contrast medium on MR contrast medium.

• Korean Journal of Radiology
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• 제25권3호
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• pp.257-266
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• 2024

Objective: To investigate molecular and functional consequences of additional exposures to iodine- or gadolinium-based contrast agents within 24 hours from the initial intravenous administration of iodine-based contrast agents through an animal study. Materials and Methods: Fifty-six Sprague-Dawley male rats were equally divided into eight groups: negative control, positive control (PC) with single-dose administration of CT contrast agent, and additional administration of either CT or MR contrast agents 2, 4, or 24 hours from initial CT contrast agent injection. A 12 µL/g of iodinated contrast agent or a 0.47 µL/g of gadolinium-based contrast agent were injected into the tail vein. Serum levels of blood urea nitrogen, creatinine, cystatin C (Cys C), and malondialdehyde (MDA) were measured. mRNA and protein levels of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) were evaluated. Results: Levels of serum creatinine (SCr) were significantly higher in repeated CT contrast agent injection groups than in PC (0.21 ± 0.02 mg/dL for PC; 0.40 ± 0.02, 0.34 ± 0.03, and 0.41 ± 0.10 mg/dL for 2-, 4-, and 24-hour interval groups, respectively; P < 0.001). There was no significant difference in the average Cys C and MDA levels between PC and repeated CT contrast agent injection groups (Cys C, P = 0.256-0.362; MDA, P > 0.99). Additional doses of MR contrast agent did not make significant changes compared to PC in SCr (P > 0.99), Cys C (P = 0.262), and MDA (P = 0.139-0.771) levels. mRNA and protein levels of KIM-1 and NGAL were not significantly different among additional CT or MR contrast agent groups (P > 0.05). Conclusion: A sufficient time interval, probably more than 24 hours, between repeated contrast-enhanced CT examinations may be necessary to avoid deterioration in renal function. However, conducting contrast-enhanced MRI on the same day as contrast-enhanced CT may not induce clinically significant kidney injury.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2002년도 제7차 학술대회 초록집
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• pp.130-130
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• 2002

Purpose： To evaluate the liver enhancement pattern of MR images obtained after administration of manganese phthalocyanine (MnPC), which is a newly developed macromolecular MR contrast agent, In experimentally implanted VX2 tumor of rabbits and compare with G4-DTPA and Mn-DPDP.

• Investigative Magnetic Resonance Imaging
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• 제23권1호
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• pp.17-25
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• 2019

We discuss recent advances in Gd-based $T_1$-weighted MR contrast agents for the mapping of cellular pH. The pH plays a critical role in various biological processes. During the past two decades, several MR contrast agents of strategic importance for pH-mapping have been developed. Some of these agents shed light on the pH fluctuation in the tumor microenvironment. A pH-responsive self-assembled contrast agent facilitates the visualization of tumor size as small as $3mm^3$. Optimization of various parameters is crucial for the development of pH-responsive contrast agents. In due course, the new contrast agents may provide significant insight into pH fluctuations in the human body.

• 전자공학회논문지
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• 제52권12호
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• pp.134-141
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• 2015

본 연구의 목적은 1.0 mol 고농도 가돌리늄 조영제가 기존의 0.5 mol MR 조영제에 비해 얼마나 높은 신호강도를 보이는지를 정량적으로 비교 분석하는 것이다. 실험을 위하여 1.0 mol Gadobutrol과 0.5 mol Gadoteridol을 사용하여 희석비율을 달리한 각각의 MR팬텀을 제작하였다. 이를 1.5T MR장비의 조영증강 T1 검사인 2D SE 와 Head-Neck Angio의 3D FLASH 두 가지 방법으로 스캔하였다. 이후 영상에서 희석비율별 신호 강도를 측정하여 이를 비교 분석하였다. 두 개의 시퀀스(2D SE, 3D FLASH)에서의 조영증강 반응시작 지점인 RSP(Reaction Starting Point)는 0.5 mol에서는 두 시퀀스 각각 6.0%, 60.0%, 1.0mol에서는 2.0%, 20.0%로 0.5 mol 조영제서의 조영증강반응이 빨리 일어났다. 최대 신호강도인 MPSI(Max Peak Signal Intensity)는 0.5 mol에서 두 시퀀스 각각 1358.8[a.u], 1573.0[a.u], 1.0mol 에서는 1374.9[a.u], 1642.4[a.u]로 최대신호강도는 두 조영제 모두 비슷하였다. 더불어 최대신호강도를 보이는 희석비율 지점인 MPP(Max Peak Point)는 0.5 mol 에서는 두 시퀀스에서 각각 0.4%, 10.0%, 1.0mol 에서는 0.16%, 1,8%로 0.5 mol 조영제의 최대신호강도가 더 빨리 형성되었다. 각 희석비율에서의 조영증강 반응면적 RA(Reaction Area)는 0.5 mol 에서는 두 시퀀스 각각 20747.4[a.u], 23204.6[a.u], 1.0 mol 에서는 12691.9[a.u], 20747.4[a.u]로 0.5 mol 조영제가 두 시퀀스에서 각각 27.4%, 11.8% 더 높았다. 본 연구를 통하여 조영증강 T1과 Head-Neck Angio 검사에서 1.0 mol 고농도 가돌리늄 조영제가 0.5 mol MR조영제에 비하여 신호반응이 느리다는 사실을 확인하였으며, 최대 신호강도인 MPSI는 1.0 mol 조영제와 0.5 mol 조영제 둘 다 비슷하여 1.0 mol 고농도 가돌리늄 조영제가 MR영상에서 반드시 높은 신호강도를 보여주지 않는다는 것을 확인 할 수 있었다.

• 대한디지털의료영상학회논문지
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• 제15권1호
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• pp.27-31
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• 2013

Perfusion MR imaging is how to use exogenous and endogenous contrast agent. Exogenous perfusion MRI methods which are dynamic susceptibility contrast using $T2^*$ effect and dynamic contrast-enhanced using T1 weighted image after injection contrast media. An endogenous perfusion MRI method which is arterial spin labeling using arterial blood flow in body. In order to exam perfusion MRI in human, technical access are very important according to disease conditions. For instance, dynamic susceptibility contrast is used in patients with acute stroke because of short exam time, while dynamic susceptibility contrast or dynamic contrast enhancement provides the various perfusion information for patients with tumor, vascular stenosis. Arterial spin labeling is useful for children, women who are expected to be pregnant. In this regard, perfusion MR imaging is required to understanding, and the author would like to share information with clinical users

• 한국자기공명학회논문지
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• 제14권1호
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• pp.9-17
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• 2010

The water proton relaxation rates increase linearly with concentrations of contrast agents, and could be expressed as a function of the concentrations. In this paper, we have investigated MR properties of two different contrast agents, $GdCl_3$ and $CoCl_2$. Relaxivity coefficients were calculated from individual contrast agent solutions, and used for predicting relaxation rates at mixtures of two contrast agents. From the experimental results, we have discussed the feasibility of constructing water solutions with the desired relaxation times using specific mixtures of contrast agents.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2003년도 제8차 학술대회 초록집
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• pp.93-93
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• 2003

To test the feasibility of rBF and rBVin the assessment of R004 sarcomas of the rat and to compare the results obtained by using Gd-DTPA and Gadomer-17 as a MR contrast agent, on the basis of the histological findings of tumor necrosis.

• Investigative Magnetic Resonance Imaging
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• 제2권1호
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• pp.73-82
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• 1998

목적 : 간특정 MR 조영제를 이요하여 간세포의 세포막을 통한 물분자의 교환 및 세포막 투과율을 정확히 측정 할 수 있는 MR 기법을 개발하고자 하였다. 대상 및 방법 : 쥐의 간세포를 분리하여 낸 후 NMR 측정을 시도하엿다. 모든 실험은 0.02MHz부터 60 MHz까지 양성자의 Larmor 주파수를 변화시킬 수 있는 IBM형 field cycling relaxometer를 사용하여 시행하였으며 spin-echo 펄스열을 사용하여 T1 자기이완시간을 측정하였다. 전오도의 간특정 조영제인 Gd-EOB-DTPA를 함유하고 있는 간세포 샘플로부터 획득한 T1 데이터를 연속분포 분석법을 사용하여 분석하였으며 이때 이론적 모델로는 Two compartmental exchange 모델을 이용하였다. 결과 : 간세포내의 물분자의 평균 거주시간은 약 250 msec이며 간세포막의 투과율에 대한 최저치는 $(1.3{\pm}0.1){\;}{\times}{\;}10^{-3}cm/sec$ 이었다. 자기이완시간의 연속적인 분포도를 구할 수 있는 CONTIN 분석기법을 적용한 결과 확산적 물분자 교환이 일어남을 밝혔고 이러한 확산적 교환의 정도가 간세포의 경우 세포내 공간에서는 작지 않다는 사실을 규명 할 수 있었다. 결론 : 연속분포 분석기법을 적용하는 경우 Gd-EOB-DTPA는 간세포에서의 물분자의 교환정도 및 세포막의 물분자에 대한 투과율을 측정하는데 매우 유용한 방법임을 확인하였고 간세포에서의 물분자의 교환속도는 적혈구에서의 물분자 교환 속도에 비해 매우 느리다는 사실을 확인하였다. 따라서 조직 특정 조영제는 해당 조직 혹은 세포의 세포막 투과율과 같은 생리학적 정보를 알아낼 수 있는 기능적 조영제로서의 유용성을 입증할 수 있었다.