Thermodynamic sorption modeling can enhance confidence in assessing and demonstrating the radionuclide sorption phenomena onto various mineral adsorbents. In this work, Ca-montmorillonite was successfully purified from Bentonil-WRK bentonite by performing the sequential physical and chemical treatments, and its geochemical properties were characterized using X-ray diffraction, Brunauer-Emmett-Teller analysis, cesium-saturation method, and controlled continuous acidbase titration. Further, batch experiments were conducted to evaluate the adsorption properties of Cs(I) and Sr(II) onto the homoionic Ca-montmorillonite under ambient conditions, and the diffuse double layer model-based inverse analysis of sorption data was performed to establish the relevant surface reaction models and obtain corresponding thermodynamic constants. Two types of surface reactions were identified as responsible for the sorption of Cs(I) and Sr(II) onto Ca-montmorillonite: cation exchange at interlayer site and complexation with edge silanol functionality. The thermodynamic sorption modeling provides acceptable representations of the experimental data, and the species distributions calculated using the resulting reaction constants accounts for the predominance of cation exchange mechanism of Cs(I) and Sr(II) under the ambient aqueous conditions. The surface complexation of cationic fission products with silanol group slightly facilitates their sorption at pH > 8.

Radionuclides in low- and intermediate-level radioactive wastes from the decommissioning process of nuclear power plants were generally immobilized by cementation methods. Ethylenediaminetetraacetic acid (EDTA), which is extensively used as a decontamination agent, can affect the behaviors of radionuclides immobilized in cement waste forms. In this study, the effects of EDTA contained in simulated radioactive decommissioning wastes on the leaching characteristics of immobilized Co and Cs and the microstructure evolution of cement waste form. Co leaching was accelerated by the formation of Co–EDTA complexes with high mobility and solubility. Cs leaching was hindered by the ion competition with other metal–EDTA complexes for releasing from the cement waste form. Cs leaching was also retarded by carbonated layer at edge of the cement waste form, which process is facilitated by the presence of EDTA. Finally, the effects of EDTA on the leaching characteristics of immobilized Cs and Co and the microstructure evolution of the cement waste form should be considered to ensure the safety of disposal for lowand intermediate-level radioactive wastes.

The permanent disposal of discharged spent nuclear fuel (SNF) and contaminated radioactive waste generated from the subsequent chemical treatments of SNF has become a serious pending issue in many countries that operate the nuclear power plants. Among the diverse engineering solutions proposed for the disposal of high-level radioactive waste (HLW), deep geological disposal (DGD) has been considered as the most proven and safe option to prevent any significant release of radionuclides into the biosphere and to predictably ensure the long-term performance of disposal system. The DGD system consists of multiple structural components; the bentonite clay-based buffer and tunnel backfills are designed to perform the primary hydrogeochemical functions of 1) inhibiting the ingress of groundwater and reactive substances that could compromise the integrity of canister and 2) retarding the migration of released radionuclides into biosphere by providing the sufficient chemisorption sites. Montmorillonite, which is a 2:1 phyllosilicate mineral belonging to smectite group, constitutes the majority of bentonite, and it mainly predominate the swelling and chemisorption capacities of the clay material. Thus, it is essentially required to thoroughly understand the chemical interactions of major radionuclides and other important substances with montmorillonite in advance to accurately evaluate the long-term retention performance of engineered barriers and to reduce the uncertainties in the safety assessment of a deep geological repository (DGR) ultimately. Thus far, sorption of dissolved species onto mineral adsorbents has been generally described and quantified using the simple sorption-desorption distribution coefficient (Kd) concept; since any specific reaction mechanisms are not considered and reflected in the Kd concept, an empirical Kd value is intrinsically dependent on the aqueous conditions under which it was measured. In this framework, substantial scientific efforts have been made to develop a robust basis for geochemically parametrizing the sorption phenomena more reliably, and the application of thermodynamic sorption modeling (TSM), which is based on the chemical principle of mass action laws, has been studied with the aim of improving overall confidence in the description of radionuclide migration under a wide range of aquatic conditions. The disposal performance demonstration R&D division of KAERI introduced a new reference Ca-bentonite clay called Bentonil-WRK (Clariant Korea) for HLW disposal research in 2021 as the domestic Ca-bentonite sources have being depleted. We successfully separated and purified Ca-montmorillonite from the Bentonil-WRK clay, and its geochemical characteristics were meticulously studied by means of XRD, BET, CEC, FT-IR analyses and controlled acid-base titration. In this work, chemical sorption behaviors of aqueous iodide and benzoate, which are a major fission product in HLW and a model ligand of complex natural organic matters present in the deep geological environment, onto the purified Camontmorillonite were assessed under ambient conditions of S/L = 5 g/L, I = 0.01 M CaCl2, pH = 4- 9, pCO2 = 10-3.4 atm, and T = 25°C. Further, their unique adsorption envelopes and corresponding thermodynamic reaction constants refined from the diffuse double layer model (DDLM)-based inverse modeling of experimental sorption data were discussed.

The safe disposal of high-level radioactive waste (HLW), including the discharged spent nuclear fuel (SNF) and contaminated by-products produced from relevant chemical treatments, has become a serious pending problem for numerous countries that operate the nuclear power plants. The deep geological disposal (DGD) has thus far been considered the most proven and viable solution for isolation of the HLW and preventing any significant release of radionuclides into the biosphere. The DGD system consists of the multiple engineered and natural barrier components. Among them, the montmorillonite-based buffer and tunnel backfills are designed to perform the two major geochemical functions: 1) preventing the ingress of groundwater and any chemicals that compromise the safety of waste canister and 2) retarding the migration of released radionuclides by providing sufficient chemisorption sites. Therefore, it is essential to investigate the sorption mechanism of radionuclides onto montmorillonite and develop a thermodynamic reaction model in advance in order to accurately predict the long-term performance of engineered barriers and to reduce the uncertainties in the safety assessment of a deep geological repository (DGR) ultimately; thus far, sorption of chemical species onto mineral adsorbents has been widely described based on the concept of sorption-desorption distribution coefficient (Kd), the value of which is intrinsically conditional, and active scientific efforts have been made to develop robust thermodynamic sorption models which offer the potential to improve confidence in demonstration of radionuclide migration under a wide range of geochemical conditions. The natural montmorillonites are generally classified into Na-type or Ca-type according to its exchangeable cation, and the Ca-montmorillonite containing clays are being considered as candidate materials for the engineered barriers of DGR in several countries; they generally have advantages of higher thermal conductivity and lower price than the Na-montmorillonite based clays, but their sorption capacities are still comparable. In this framework, we aimed to investigate the chemical interactions of Ca-montmorillonite with selenite [Se(IV)], which is a major oxyanionic species in terms of HLW disposal, and develop a reliable thermodynamic sorption model (TSM). The present work summarizes the characterization of Ca-montmorillonite separated from the newly adopted reference bentonite (Bentonil-WRK) by means of XRD, BET, FTIR, CEC measurement, and acid-base titration. Further, its sorption behaviors with aqueous selenite species under aqueous conditions of S/L = 5 g/L, I = 0.01-0.1 m CaCl2, pH = 4.5-8.5, pCO2 = 10-3.5 atm, and T = 25°C were examined, and the resulting thermodynamic data are discussed as well.

A disposal system for spent nuclear fuel divides into two parts; (1) engineered barriers including spent nuclear fuel, canister, buffer and backfill, (2) natural barriers surrounding engineered barriers. Sorption and diffusion are main retardation mechanisms for the migration of released radionuclides. We analyzed the sorption properties of radionuclides for bentonite as a buffer material and collected/ evaluated the distribution coefficients for the purpose of safety assessment for the deep geological disposal of a spent nuclear fuel. Through this, we presented recommended distribution coefficients for radionuclides required for the safety assessment. This work included the radionuclides as follows; alkali and alkaline earth metals (Cs, Sr, Ba), lanthanides (Sm), actinides (Ac, Am, Cm, Np, Pa, Pu, Th U), transition elements (Nb, Ni, Pd, Tc, Zr), and others (C, Cl, I, Rn, Se, Sn). The sorption of radionuclides affected various geochemical conditions such as pH/carbonates, redox potential, ionic strength, radionuclide concentration, kinds and amounts of minerals, and microbes. Among the evaluated radionuclides, Cs, Ni, Pd, and Ra is sensitive to the ionic strength, while Np, Pu, U, Se, and, Tc is sensitive to the redox condition. For the evaluation of distribution coefficients, the data from Sweden (SKB), Finland (Posiva), Switzerland (Nagra), and Japan (JAEA) were collected, analyzed, and the recommended distribution coefficients were suggested.

The deep geological disposal system is aimed to permanently isolate the high-level radioactive waste from the biosphere through a multi-barrier system composed of engineered and natural barriers. The buffer material used for the engineered barrier should have the performance to prevent and retard the migration of radionuclides to the outside of the deep disposal facility when radionuclides are released from a disposal canister by infiltration of groundwater after a long period of time. When the hydraulic conductivity of compacted bentonite is sufficiently low, the migration of radionuclides released into the surrounding rock can be significantly reduced since they are sorbed to bentonite during the diffusion process. Therefore, an investigation on diffusion of radionuclides in compacted bentonite is a fundamental task to obtain essential data for the safety assessment of the deep geological disposal system. The migration of radionuclides by diffusion can be evaluated by diffusion coefficient. In order to obtain the apparent diffusion coefficients of Sr, Sm, and Eu in compacted Ca-bentonite (1.6 g/cm3) a through-diffusion experiment have been carrying out. A cylindrical apparatus consists of a source cell with an appropriate concentration of radionuclides and diffusion cell filled with radionuclide free solution where the concentration is gradually increased by diffusion of radionuclides. The compacted bentonite was installed between the both cells. The sample used for the experiment is a Ca-type bentonite named Bentonil-WRK, and the diffusion experiment was performed under an oxidizing condition using a synthetic groundwater simulating KURT groundwater composition. The diffusion experiment will be terminated when an increasing rate of concentration of nuclides in the diffusion cell becomes constant over time. The concentration change with regard to the geochemical characteristic of the nuclide may appear to be apparently slow.In this study, the experimental results of the through-diffusion test of Sr, Sm, and Eu in the initial stage (~4 months) were presented. Through the results of the initial stage, the period of the through-diffusion experiment can be rearranged and also it is expected that the initial results provide the qualitative and quantitative diffusion properties of each nuclide.

The deep geological repository consisting of a multi-barrier system (engineered and natural barriers) is generally designed to isolate the high-level radioactive waste. The natural barrier is outermost portion to secure safety of the disposal. Crystalline rocks are considered for potential geological repository media to retard and inhibit the migration of radionuclides when the radionuclides leak from the canister and break through the engineered barrier. Sorption and diffusion processes play a major role in retardation of the radionuclides in deep underground environment. In order to evaluate the migration of radionuclides in the safety assessment or geochemical modelling, distribution coefficient and diffusivity of radionuclides are required as input data. In this study, we performed mineralogical and geochemical analysis for a crystalline rock (e.g., granite) to use the sorption and diffusion experiment. The fresh rock samples are obtained from a deep core samples (DB-2) drilled up to 1 km from the surface at KURT (KAERI Underground Research Tunnel) site. For the optical and microscopic examination, thin sections of the rock sample were provided. The rock samples were crushed into powder size to analyze major and trace elements of the whole-rock aliquots. The powdered specimens also used for mineral identification and measurement of specific surface area. The major constituent minerals of the granite are plagioclase, quartz, and K-feldspar and the minor minerals are phlogopite, biotite, and chlorite. According to the results of geochemical analysis, the granite specimens generally contain more than 70wt% of SiO2 and 8wt% of total alkali oxides (Na2O + K2O). The trace elements normalized to primitive mantle compositions show positive Cs, Rb, U, K, and Pb anomalies and negative Nb and Ti anomalies. The rock samples have an average density of 2.62 g·cm−3 and an average porosity of 0.222%. The crushed samples represent the specific surface area of 0.2087 m2·g−1 for the 75–150 μm fraction and 0.1616 m2·g−1 for the 150–300 μm fraction by BET method, respectively. The granite specimens will be used for the sorption and diffusion experiments to evaluate the radionuclides’ geochemical behaviors. The mineralogical and geochemical properties provided in this study can be useful in understanding the sorption and diffusion processes of significant radionuclides under the geological disposal environments.

Numerous low-and intermediate level radioactive wastes were generated from the decommissioning processes of nuclear power plants. Radionuclides such as Co and Cs contained in decommissioning wastes should be immobilized to prevent the release of radionuclides from the wastes due to its harmful impacts on ecosystem by high radioactivity and long half-life. Ethylenediaminetetraacetic acid (EDTA) used as decontamination agent can be contained in cement waste during decommissioning process of nuclear power plants. In addition, EDTA can be stably and strongly bound with radionuclides, resulting in the acceleration of the nuclide release from solidified cement matrix. Here, we investigated the effects of EDTA on leaching behaviors of Co and Cs immobilized in the cement specimen. The leaching tests were performed according to the ANS 16.1 “Measurement of the leachability of solidified low-level radioactive wastes by a short-term test procedure”. From the results, an increase in the EDTA content in the cement specimen led to an increase in Co leaching, whereas a decrease in Cs leaching. Leaching of Cs was dominantly controlled by diffusion from the pore space of the cement specimen to the solution. The effective diffusion coefficient and leachability index of nuclide were determined using the diffusion-release models of ANS 16.1. The results of present study can be used in the safety assessment for disposal of the radioactive waste generated by decommissioning of nuclear power plants.

FTIR (Fourier Transform Infrared) and Raman spectra of KJ-II bentonite provided by Clariant Korea were compared with those of MX-80 bentonite. The FTIR spectra were obtained using a Nicolet 5 FTIR spectrometer (Fisher Scientific) equipped with a diamond ATR (Attenuated Total Reflection) module. The spectra were collected for 64 scans with a resolution of 4 cm−1. Raman spectra were obtained using an optical microscope (Olympus, BX43) and a spectrometer (Andor, SR- 500). The laser beam was focused using an objective lens with a magnifying power of 50. The backscattered light from the sample was collected into an optical fiber with a core diameter of 0.4 mm. The Raman signals were recorded with CCDs (Andor, DV401A-BV for 532 nm laser wavelength and DV420A-OE for 638 and 785 nm laser wavelengths). Each pixel of CCD received the signal for 1 s and its 1000 times accumulated data were collected. The FTIR spectra of the two bentonite samples are very similar. The FTIR spectra of both bentonites showed absorption bands at 3623, 3399, 3231 cm−1 in the higher wavenumber region and at 1637, 1443, 1117, 997, 914, 887, 847, 797, 611, 515, 414 cm−1 in the lower wavenumber region. A sharp band at 3623 cm−1 and the strong band at 997 cm−1 correspond to the OH stretching of structural hydroxyl groups and the Si-O stretching vibration, respectively. In addition to these clear bands, several absorption bands observed in this experiment are well matched with the results reported in various literatures. Unlike the FTIR spectrum, it is not easy to observe the Raman bands of bentonite. The reason is that strong fluorescence interferes with the Raman spectrum. The two bentonite samples showed different fluorescence intensities. In the case of MX-80 bentonite, no clear Raman band was observed due to the influence of very strong fluorescence. KJ-II bentonite showed a relatively weak fluorescence intensity and Raman bands were partially visible at around 147, 260, 397, 709, and 1279 cm−1. In particular, the band at 1279 cm−1 is wide and sturdy. It was observed that the non-powder samples showed a better quality spectra. The Raman characteristics of KJ-II bentonite, which depend on the incident laser wavelength and the sample pretreatment, are discussed in detail.

A deep geological disposal system, which consists of the engineered and natural barrier components, is the most proven and widely adopted concept for a permanent disposal of the high level radioactive waste (HLW) thus far. The clay-based engineered barrier is designed to not only absorb mechanical stress caused by the geological activities, but also prevent inflow of groundwater to canister and outflow of radionuclides by providing abundant sorption sites. The principal mineralogical constituent of the clay material is montmorillonite, which is a 2:1 phyllosilicate having two tetrahedral sheets of SiO2 sandwiching an octahedral sheet of Al2O3. The stacking of SiO2 and Al2O3 sheets form the layered structures, and ion-exchange and water uptake reactions occur in the interlayer space. In order to reliably assess the radionuclide retention capacity of engineered barrier under wide geochemical conditions relevant to the geological disposal environments, sorption mechanisms between montmorillonite and radionuclides should be explicitly investigated in advance. Thus far, sorption behavior of mineral adsorbents with radionuclides has been quantified by the sorption-desorption distribution coefficient (Kd), which is simply defined as the ratio of radionuclide concentration in the solid phase to that in the equilibrium solution; the Kd value is conditional, and there have been scientific efforts to develop geochemically robust bases for parameterizing the sorption phenomena more reliably. In this framework, application of thermodynamic sorption model (TSM), which is theoretically based on the concept of widely accepted equilibrium models for aquatic chemistry, offers the potential to improve confidence in demonstration of radionuclide sorption reactions on the mineral adsorbents. Specifically, it is generally regarded in the TSM that coordination of radionuclides on montmorillonite takes place at the surficial aluminol and silanol groups while their ion-exchange reactions occur in the interlayer space also. The effects of electrical charge on the surface reactions are additionally corrected in accordance with the numerous theories of electrochemical interface. The present work provides an overview of the current status of application of TSM for quantifying sorption behaviors of radionuclides on montmorillonite and experimental results for physical separation and characterization of Ca-montmorillonite from the newly adopted reference bentonite (Bentonil- WRK) by means of XRD, BET, FTIR, CEC measurement, and acid-base titration. The determined mineralogical and chemical properties of the montmorillonite obtained will be used as input parameters for further sorption studies of radionuclides with the Bentonil-WRK montmorillonite.

목 적：고자장(3.0T) MRI에서 교정 후 잔존하는 강자성체 인공물에 대해 SEMAC 기법의 단계별 적용을 통하여 T1, T2 검사 시퀀스의 축상면 인공물의 장･단축 길이 감소 정도와 신호대 잡음비 측정을 통하여 인공물 감소를 위한 최적의 단계를 알아보고 임상에서 추가적인 검사 방법으로 적용하고자 한다. 대상 및 방법：3.0T MRI (MAGNETOM Skyra, Siemens, Munich, Germany)를 사용하여 자체 제작된 손목 (Wrist and hand) 팬텀 속에 치료용 보루스와 치과용 stainless steel wire (18 × 25 mm)를 삽입하여 고정하였다. 고신호 강도를 구현하기 위해서 두･부 전용 코일(64 channel)을 사용하여 검사를 진행하였 으며, 연구에 사용한 펄스 시퀀스는 T1 TSE, T2 TSE에 SEMAC 기법을 적용하였고, 추가적인 (additional) 위상 부호화 단계(phase encoding steps, PES)를 정성적(6-15), 정량적(6-10)까지 변화 시켜 10회 반복 측정하여 실험하였다. 정량적 평가는 영상 왜곡이 가장 심하게 일어난 부위(영상 18번)에 서 좌･우측으로 나누고 장･단축의 길이를 계측하였고, 인공물 영향이 없는 3곳을 좌･우측 각각 지정하여 신호대 잡음비(signal to noise ratio, SNR)를 계측하였다. 정성적 평가는 이미지의 질을 내･외부 평가 자 각각 3명이 영상 평가 기준에 맞춰 5점 척도화하여 평가하였다. 결 과：T2 SEMAC의 인공물에 대한 정량적 분석 결과는 PES가 6→7, 7→8, 8→9, 9→10 변화할 때 RT: 장축 길이는 0.11%, 0.02%, 0.10%, 0.02%로 감소, 단축 길이는 0.19%, 0.04%, 0.22%, 0.07%로 감 소하였다. LT는 장축 길이: 0.12%, 0.02%, 0.10%, 0.06%로 감소, 단축 길이: 0.20%, 0.09%, 0.18%, 0.3%로 감소하였다. T1 영상의 정량적 분석의 경우는 RT의 장축 길이: 0.17%, 0.01%, 0.11%, 0.01% 로 감소, 단축 길이는 0.14% 0.01%, 0.11%, 0.02%로 감소하였다. LT의 장축 길이: 0.20%, 0.01%, 0.09%, 0.01% 감소, 단축 길이: 0.13%, 0.03%, 0.11%, 0.01%로 감소되는 결과를 나타내었다 (p<0.01). T2(RT)의 신호대 잡음비 측정 결과 PES가 6-10까지 증가할 때 101.92, 105.25, 105.44, 104.44, 103.47, T2(LT): 95.30, 98.98, 97.22, 96.61, 95.74, T1(RT): 177.24, 175.50, 296.06, 299.88, 313.71이고, T1(LT): 159.67, 158.79, 246.75, 226.75, 259.67로 나타났다. 정성적 분석의 경우 T2 영상에서 5점 척도를 기준으로 SEMAC PES가 6- 15일 경우 1.50, 2.16, 2.16, 2.50, 2.83, 3.16, 3.33, 3.83, 4.50, 4.50점으로 내･외부 관측자가 영상을 평가하였고(p<0.01), T1 영상에서 6- 15일 경우 1.50, 2.16, 2.16, 2.33, 2.66, 3.33, 3.00, 3.66, 4.00, 4.16점으로 평가를 하였다 (p<0.01). 결 론：교정 후 치아의 유지를 위해 남아 있는 강자성체 인공물이나 불가피하게 두･경부에 잔존하는 물질로 인해 검사에 제한 사항이 발생을 할 경우 T2 SEMAC의 경우 PES 7, T1 SEMAC의 경우는 6-8(SNR, artifact, scan time 고려시: PES 8, PES 7, PES 6)을 권고한다. 본 연구에서 제시한 최적의 T1, T2의 SEMAC PES를 참고하여 임상에 적용한다면 기존 검사법과 비교 시 영상의 질 향상에 도움이 될 것이라 판단된다.

목 적：고자장(3.0T) MRI에서 교정 후 잔존하는 강자성체 인공물에 대해 SEMAC 기법의 단계별 적용을 통하여 T1, T2 검사 시퀀스의 축상면 인공물의 장･단축 길이 감소 정도와 신호대 잡음비 측정을 통하여 인공물 감소를 위한 최적의 단계를 알아보고 임상에서 추가적인 검사 방법으로 적용하고자 한다. 대상 및 방법：3.0T MRI (MAGNETOM Skyra, Siemens, Munich, Germany)를 사용하여 자체 제작된 손목(Wrist and hand) 팬텀 속에 치료용 보루스와 치과용 stainless steel wire (18 × 25 mm)를 삽입하여 고정하였다. 고신호 강도를 구현하기 위해서 두･부 전용 코일(64 channel)을 사용하여 검사를 진행하였으며, 연구에 사용한 펄스 시퀀스는 T1 TSE, T2 TSE에 SEMAC 기법을 적용하였고, 추가적인 위상 부호화 단계(phase encoding steps, PES)를 정성적(6-15), 정량적(6-10)까지 변화시켜 10회 반복 측정하여 실험하였다. 정량적 평가는 영상 왜곡이 가장 심하게 일어난 부위(영상 18번) 에서 좌･우측으로 나누고 장･단축의 길이를 계측하였고, 인공물 영향이 없는 3곳을 좌･우측 각각 지정하여 신호대 잡음비 (signal to noise ratio, SNR)를 계측하였다. 정성적 평가는 이미지의 질을 내･외부 평가자 각각 3명이 영상 평가 기준에 맞춰 5점 척도화하여 평가하였다. 결 과：T2 SEMAC의 인공물에 대한 정량적 분석 결과는 PES가 6→7, 7→8, 8→9, 9→10 변화할 때 RT 장축 길이는 0.11%, 0.02%, 0.10%, 0.02%로 감소, 단축 길이는 0.19%, 0.04%, 0.22%, 0.07%로 감소하였다. LT 장축 길이: 0.12%, 0.02%, 0.10%, 0.06%로 감소, 단축 길이: 0.20%, 0.09%, 0.18%, 0.3%로 감소하였다. T1 영상의 정량적 분석의 경우는 RT의 장축 길이: 0.17%, 0.01%, 0.11%, 0.01%로 감소, 단축 길이는 0.14% 0.01%, 0.11%, 0.02%로 감소하였다. LT의 장축 길이: 0.20%, 0.01%, 0.09%, 0.01% 감소, 단축 길이: 0.13%, 0.03%, 0.11%, 0.01%로 감소되는 결과를 나타내었다 (p<0.01). T2(RT)의 신호대 잡음비 측정 결과 PES가 6-10까지 증가할 때 101.92, 105.25, 105.44, 104.44, 103.47, T2(LT): 95.30, 98.98, 97.22, 96.61, 95.74, T1(RT): 177.24, 175.50, 296.06, 299.88, 313.71이고, T1(LT): 159.67, 158.79, 246.75, 226.75, 259.67로 나타났다. 정성적 분석의 경우 T2 영상에서 5점 척도를 기준으로 SEMAC PES가 6~15일 경우 1.50, 2.16, 2.16, 2.50, 2.83, 3.16, 3.33, 3.83, 4.50, 4.50점으로 내･외부 관측자가 영상을 평가하 였고(p<0.01), T1 영상에서 6~15일 경우 1.50, 2.16, 2.16, 2.33, 2.66, 3.33, 3.00, 3.66, 4.00, 4.16점으로 평가를 하였다(p<0.01). 결 론：교정 후 치아의 유지를 위해 남아 있는 강자성체 인공물이나 불가피하게 두･경부에 잔존하는 물질로 인해 검사에 제한 사항이 발생을 할 경우 T2 SEMAC의 경우 PES 7, T1 SEMAC의 경우는 6~8(SNR, artifact, scan time 고려시: PES 8, PES 7, PES 6)을 권고한다. 본 연구에서 제시한 최적의 T1, T2의 SEMAC PES를 참고하여 임상에 적용한다면 기존 검사법과 비교 시 영상의 질 향상에 도움이 될 것이라 판단된다.

목 적 : 수술 전·후 연부 조직 종양과 전이암 의심 환자에 대해 역동적 조영증강 검사와 확산 강조영상을 적용하여 도출된 매개변수의 수치와 시간-농도 곡선 그래프를 분석해 악성 병변의 진단 유용성을 확인하고자 한다. 대상 및 방법 : 본 연구는 후향적 연구로서 임상윤리 위원회의 승인을 얻어 진행하였으며 연구 기간은 2015년 02월 01일부 터 2016년 07월 31일까지 핵의학 검사나 전산화 단층 촬영을 선행하고 정확한 병변의 진단을 위해 MRI 검사를 의뢰받은 환자 51명을 대상으로 하였다. 연구에 사용된 프로토콜은 본원에서 시행되고 있는 역동적 조영증강 자기공명 검사에 최적 화된 검사기법과 확산 강조영상을 사용하였다. 정량적 평가는 획득된 데이터를 Tissue 4D를 사용하여 매개변수를 도출하였으며, 확산 강조영상에서 확산 제한되는 부분과 현성 확산 계수에서 신호 감소를 보이는 병변에 관심 영역을 설정하여 계측 하였다. 통계적 분석은 독립 표본 t-test와 상관 분석을 사용하였다. 결 과 : 계측된 매개변수의 평균값은 연부 조직 종양의 경우 Ktrans, Kep, Ve, ADCminimal, ADCmaximal, ADCmean, TCCpattern/type은 각각 0.161 ± 0.012, 0.661 ± 0.041, 0.268 ± 0.003, 0.828 ± 0.393, 1.218 ± 0.502, 1.304 ± 0.435, 2.675 ± 0.674, 5.500 ± 1.874이며, 전이암 의심 환자의 경우는 0.126 ± 0.019, 0.711 ± 0.012, 0.219 ± 0.024, 0.879 ± 0.392, 1.285 ± 0.412, 1.074 ± 0.393, 2.787 ± 0.606, 5.590 ± 1.161로 나타났다(p>0.05). 과 혈관성으로 인하여 확산 제한, 초관 류, ADC 신호감소가 동시에 나타난 경우는 연부 조직 종양은 20명 중 8명이고 평균적인 값들은 Ktrans, Kep, Ve, ADC 순으 로 각각 0.176 ± 0.121, 0.655 ± 0.297, 0.274 ± 0.146, 0.701 ± 0.203 이었다. 전이암의 경우는 31명중 9명의 평균값은 Ktrans, Kep, Ve, ADC 순으로 각각 0.133 ± 0.083, 0.698 ± 0.202, 0.187 ± 0.111, 0.889 ± 0.283 이었다. 혈관종, 탄력 섬유종 연골육종, 내연골종의 경우는 확산 제한과 초관류를 동시에 나타내지 않았다. 결 론 : 악성의 경우 매개변수의 기준값은 Ktrans, Kep, Ve, ADCminimal, ADCmaximal, ADCmean은 0.14 ± 0.09, 0.73 ± 0.47, 0.21 ± 0.11, 0.84 ± 0.40, 1.02 ± 0.40, 1.21 ± 0.43, TCC의 pattern은 Ⅲ(3)이고 type은 ⅴ(5), ⅵ(6), ⅶ(7) 이었다. 악성 종 양의 경우과 혈관성으로 인해 확산 제한과 초관류가 동시에 나타났으며, 역동적 조영증강에서 도출된 Ktrans, Kep, Ve의 값과 TCC 그래프의 pattern 분석을 상호보완적으로 적용했을 때 고식적 검사에 비해 정확한 질환 판별이 가능하였다. 그리고 수 술 전·후 병변에 잔존하는 종양과 항암 치료 후 개선되는 양상을 평가하는데 있어 매우 유용할 것이라 사료된다.

목 적 : 본 연구는 수술 전 양성 및 악성 간 병변 환자에 대하여 자유호흡기법(free breathing technique)을 사용하여 b-value (50, 500, 800, 1000)를 변환시켜 조영제 주입 전·후 현성확산계수가 어떤 수치적인 변화를 나타내는지 연구하고 악성 종양의 평가 자료로 유용한지 알아보고자 하였다. 대상 및 방법 : 본 연구는 후향적 연구로써 임상윤리위원회(institutional review board, IRB)의 승인(PNUHIRB-17)을 얻어 진행하였으며 연구 기간은 2015년 11월 01일부터 2016년 01월 30일까지 부산 소재 일개 P대학교 병원을 내원하여 수술전 간 MRI 검사를 의뢰 받은 환자 38명을 대상으로 하였다. 연구에 사용된 프로토콜(protocol)은 본원에서 시행되고 있는 간 검사에 최적화된 검사기법(TR:5100 ms, TE: 79 ms, SPAIR, NEX: 6, b-value type: 50, 500, 800, 1000)으로 조영제 주입 전 축삭면 확산강조영상을 자유호흡기법으로 영상을 획득하고 PRIMOVIST 10 ml (Gd-EOB-DTPA) 주입후 20분 지연기(hepatobilliary phase)에 동일하게 반복 시행하였다. 사용된 확산강조영상은 SE single-shot EPI (echo planar imaging)을 이용하여 b-value값을 50, 500, 800, 1000 s/mm2으로 세분화하여 검사를 하였다. 정량적 평가시 Image J와 work station을 사용하여 평가 하였으며 세분화 되어있는 b-value 값에 따라 ADC map을 나타내고, 이에 대하여 병변에 관심영역을 설정하여 현성확산계수를 구하였다. 통계적 분석은 대응표본 t-Test를 사용하였으며, p < 0.05 일때 통계적으로 유의하게 평가되었다. 결 과 : 간세포암의 경우 조영제 주입 전과 후의 현성확산계수의 수치는 pre ADC (500, 800, 1000: 1.238, 1.040, 1.007 × 10-3 s/mm2), post ADC (500, 800, 1000: 1.225, 1.094, 1.002 × 10-3 s/mm2)를 나타내었다(p>0.05). 간전이암의 경우 pre ADC (500, 800, 1000: 1.450, 1.472, 1.332 × 10-3 s/mm2), post ADC (500, 800, 1000: 1.438, 1.441, 1.354 × 10-3 s/mm2)를 나타냈고(p > 0.05), 혈관종의 경우 pre ADC (500, 800, 1000: 1.591, 1.365, 1.217 × 10-3 s/mm2)와 post ADC (500, 800, 1000: 1.906, 1.614, 1.396 × 10-3 s/mm2)는 변화 있는 결과를 나타내었다(p>0.05). 결 론 : 결론적으로 양성 종양의 경우 조영제 주입 전과 후의 결과의 연관성이 크지 않았고, 규칙성이 없었다. 하지만 간세포암의 악성병변(LR-5)의 경우 조영제 주입 후가 양성 병변에 비해 통계적으로 의미 있게 낮은 현성계수의 값을 보였으며, 정성적 분석에 향상을 가져왔다. 본 연구에서 제시한 바와 같이 복부 확산강조영상의 경우 질병과 검사 순서에 따라 현성확산계수의 결과 값과 확산강조영상의 명확도가 다르게 측정 될 수 있으므로 조영 전과 후의 확산강조영상을 병행한다면 좋을 것이라고 사료되며, 조영후의 현성확산계수와 이용 가능한 검사 시퀀스를 병행한다면 양성 및 악성 질환 감별의 진단에 효율성을 가져올 것이라고 판단되었다

목 적 : 본 연구의 목적은 유방 자기공명영상검사시 확산강조영상(diffusion-weighted imaging, DWI)에서 발생하는 심장과 폐에 의한 불수의적 움직임 인공물(involuntary motion artifact)과 Reduced-FOV EPI 기법에서 발생하는 둘러겹침 인공물(aliasing artifact)을 추가적인 사전 포화 기법을 사용하여 이를 저감화시키고 영상의 질을 개선하여 최적화된 사전 포화 펄스의 필요성을 확인하고자 한다. 대상 및 방법 : 2014년 08월 01일부터 11월 30일까지 유방의 수술 전 검사로 내원한 비만 여성 환자 38명(평균 연령: 52.50 ± 12.87세)을 대상으로 동일 환자에게 사전포화 펄스의 수와 위치를 달리 적용하여 확산강조영상검사를 시행하였다. 연구에 사용된 장비는 유방 검사에 최적화된 3.0T (Tim Trio: Siemens Medical solutions, Erlangen, Germany)와 고신호 강도를 획득하기 위한 유방 전용 코일(8 channel breast coil)을 사용하였다. 영상 변수는 반복 시간(TR): 5200 ms, 에코 시간(TE): 74 ms, 화소 배열 수(matrix): 192 × 80, 여기 횟수(NEX): 9, 절편 두께(thickness): 5 mm, 영상 영역(FOV): 380 ± 20 mm, FOV-phase: 52.6(%), saturation pulse thickness: 150 mm, 지방 소거 기법(fat suppression): SPAIR를 사용하였다. 영상의 평가와 분석은 정성적 분석, 정량적 분석을 사용하였고 통계적 유의성은 Paired T-test 와 Wilcoxon rank test를 사용하였다. 결 과 : 정성적 분석의 경우 확산경사계수(b-value) 0에서 사전 포화 펄스를 1개 사용 할 경우(1 saturation pulse band, 1 S. P. B)는 2.63 ± 0.59, 2 S. P. B의 경우 3.21 ± 0.60, 확산경사계수 1000에서 1 S. P. B의 경우는 2.52 ± 0.64, 2 S. P. B는 3.06 ± 0.66, 현성확산계수(ADC)에서 1 S. P. B에서는 2.67 ± 0.55, 2 S. P. B에서는 3.10 ± 0.53을 나타내었다. 정량적 분석의 경우 확산경사계수 0에서만 평가를 하였다. 1 S. P. B에서 신호 대 잡음비는 병변 부위(ROIlesion)에서 226.39 ± 124.29, 병변 근접 부위(ROInear lesion)에서 160.75 ± 103.71, 지방(ROIfat)에서 19.34 ± 13.02 을 나타내었고, 대조도 대 잡음비의 경우는 병변을 기준으로 하였을 때 병변과 병변근접 부위(CNRlesion-near lesion)는 71.55 ± 81.30, 병변과 지방(CNRlesion-fat)은 212.96 ± 113.91를 나타내었다. 2 S. P. B에서 신호 대 잡음비는 병변 부위에서 261.93 ± 127.59, 병변 근접 부위에서 182.82 ± 114.80, 지방에서 23.32 ± 14.52, 대조도 대잡음비는 병변을 기준으로 병변과 병변 근접 부위는 79.12 ± 87.03, 병변과 지방은 238.59 ± 121.84를 나타내었다. 사전 포화 펄스의 추가적인 사용으로 병변에서 변화율이 15.69%, 병변 근접 부위에서 변화율은 13.72%, 지방에서 변화율은 20.63%의 증가를 보였으며, 대조도 대 잡음비의 경우는 병변과 병변 근접 부위의 경우 10.58%, 병변과 지방 부위의 경우 12.03%의 증가를 나타내었다. 결 론 : 사전 포화 펄스의 추가 적용으로 확산강조영상 획득시 위상 부호화 방향(phase encoding direction)으로 발생하는 불수의적 움직임 인공물과 둘러겹침 인공물이 저감화되었고, 질환 부위와 정상 조직 간의 경계가 명확하게 구분되었으며 영상의 질이 개선되었다. 본 연구에서 제시한 추가적인 사전 포화 펄스 기법과 Reduced-FOV 기법을 변형하여 적용을 한다면 영상의 개선과 재검사의 빈도를 감소시킬 수 있을 것이라고 판단되었다.