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Goo, Hyun Woo,Yang, Dong Hyun,Park, In-Sook,Ko, Jae Kon,Kim, Young Hwee,Seo, Dong-Man,Yun, Tae-Jin,Park, Jeong-Jun RADIOLOGICAL SOCIETY OF NORTH AMERICA INC 2007 Journal of Magnetic Resonance Imaging Vol.25 No.4
<B>Purpose</B><P>To evaluate the usefulness of time-resolved three-dimensional (3D) magnetic resonance angiography (MRA) using diluted contrast agent (CA) in patients who had undergone a Fontan operation or bidirectional cavopulmonary connection (BCPC).</P><B>Materials and Methods</B><P>Time-resolved 3D MRA (10 dynamic data sets, two seconds per dynamic data set) using parallel imaging and keyhole data sampling was performed on 15 patients (median age = 10 years, range = 1–20 years) who had undergone a Fontan operation (N = 11) or BCPC (N = 4). Diluted gadolinium (Gd) contrast agent (CA) was intravenously injected into the arm and/or leg veins. The flow dynamics and morphology of pulmonary circulation, and lung perfusion were assessed.</P><B>Results</B><P>Preferential or balanced pulmonary blood flow from each systemic vein was visualized on time-resolved 3D MRA in all patients. In addition, occlusion/stenosis of the central thoracic vein (N = 4) and pulmonary artery (N = 6), systemic venous (N = 5) and arterial (N = 6) collaterals, and lung perfusion defect (N = 4) were identified. Persistent hepatic venous plexus, pulmonary arteriovenous malformation, and axillary arteriovenous fistula were delineated in three patients, respectively.</P><B>Conclusion</B><P>Time-resolved 3D MRA with diluted CA is useful for evaluating patients who have undergone a Fontan operation or BCPC because it can reveal the flow dynamics and morphology of pulmonary circulation, and lung perfusion status. J. Magn. Reson. Imaging 2007. © 2007 Wiley-Liss, Inc.</P>
Lee, Nam Kyung,Kim, Suk,Kim, Gwang Ha,Heo, Jeong,Seo, Hyung Il,Kim, Tae Un,Kang, Dae Hwan RADIOLOGICAL SOCIETY OF NORTH AMERICA INC 2012 JOURNAL OF MAGNETIC RESONANCE IMAGING Vol.36 No.3
<P><B>Abstract</B></P><P><B>Purpose:</B></P><P>To determine the significance of the delayed hyperintense portal vein sign in Gd‐EOB‐DTPA‐enhanced magnetic resonance imaging (MRI).</P><P><B>Materials and Methods:</B></P><P>This retrospective study was approved by the Institutional Review Board and the requirement for informed patient consent was obtained. Six‐hundred and seventy patients who underwent Gd‐EOB‐DTPA‐enhanced MRI were included in the study. Two readers who were blinded to clinical records reviewed MR images in consensus. The delayed hyperintense portal vein sign was defined if the portal vein appeared more hyperintense than surrounding liver parenchyma on the 30‐minute delayed hepatobiliary phase. The frequency of the delayed hyperintense portal vein sign and the association between the sign and serum biochemical tests were assessed. Multivariate analysis was performed to identify which variables were associated with the sign. Optimal cutoff values of variables for reflecting the sign were obtained with ROC analysis.</P><P><B>Results:</B></P><P>The delayed hyperintense portal vein sign was observed in 13.0%. In multivariate analysis, a direct bilirubin level was associated with the delayed hyperintense portal vein sign. Optimum cutoff value for reflecting the delayed hyperintense portal vein sign was 2.18 mg/dL (sensitivity, 89%; specificity, 96%).</P><P><B>Conclusion:</B></P><P>The delayed hyperintense portal vein sign in Gd‐EOB‐DTPA‐enhanced MRI can potentially be used to reflect hepatobiliary function. J. Magn. Reson. Imaging 2012;36:678–685. © 2012 Wiley Periodicals, Inc.</P>
Kim, So Yeon,Soo Lee, Seung,Bumwoo Park,,Kim, Namkug,Kim, Jeong Kon,Park, Seong Ho,Byun, Jae Ho,Song, Ki Jun,Koo, Ja‐,heung,Kyung Choi, Eun,Lee, Moon‐,Gyu RADIOLOGICAL SOCIETY OF NORTH AMERICA INC 2012 JOURNAL OF MAGNETIC RESONANCE IMAGING Vol.36 No.5
<P><B>Abstract</B></P><P><B>Purpose:</B></P><P>To evaluate the effect of diffusion‐weighted imaging (DWI) methods, apparent diffusion coefficient (ADC) calculation methods, and selection of b‐values on the ADCs and the measurement reproducibility of malignant hepatic tumors.</P><P><B>Materials and Methods:</B></P><P>Nineteen patients with pathologically confirmed malignant hepatic tumors underwent breath‐hold DWI (b‐values = 0, 50, 500 s/mm<SUP>2</SUP>) and respiratory‐triggered DWI (0, 50, 300, 500, 1000 s/mm<SUP>2</SUP>) twice on a 1.5 T magnetic resonance imaging (MRI) scanner. ADCs were calculated using a two b‐value and/or a multiple b‐value method. The reproducibility of the ADC measurements was evaluated from the intraclass correlation coefficients (ICCs) and the 95% Bland–Altman limit‐of‐agreement (LOA).</P><P><B>Results:</B></P><P>The ADCs were different according to the DWI methods (<I>P</I> = 0.040–0.282), ADC calculation methods (<I>P</I> = 0.003–0.825), and the choice of b‐values (<I>P</I> < 0.001). The ADC tended to be more reproducible with use of breath‐hold DWI (ICC: 0.898–0.933; LOA, 18.8%–24.0%) than respiratory‐triggered DWI (ICC: 0.684–0.928; LOA, 15.0%–31.9%) (<I>P</I> = 0.008–0.122). For respiratory‐triggered DWI, the multiple b‐value method using five b‐values had better reproducibility than the two b‐value method for measurement of ADC (<I>P</I> = 0.009–0.221).</P><P><B>Conclusion:</B></P><P>The DWI method, ADC calculation method, and selection of b‐values potentially influence the ADCs and the reproducibility of malignant hepatic tumors. ADCs calculated from breath‐hold DWI are more reproducible than from respiratory‐triggered DWI. A multiple b‐value method may improve the reproducibility of respiratory‐triggered DWI. J. Magn. Reson. Imaging 2012;36:1131–1138. © 2012 Wiley Periodicals, Inc.</P>
Suh, Ji‐,Yeon,Cho, Gyunggoo,Song, Youngkyu,Lee, Chang Kyung,Kang, Jong Soon,Kang, Moo Rim,Park, Sung Bin,Kim, Young Ro,Kim, Jeong Kon RADIOLOGICAL SOCIETY OF NORTH AMERICA INC 2012 JOURNAL OF MAGNETIC RESONANCE IMAGING Vol.35 No.6
<P><B>Abstract</B></P><P><B>Purpose:</B></P><P>To evaluate the reliability and accuracy of the apparent diffusion coefficient (ADC) for monitoring antiangiogenic treatment in a longitudinal study.</P><P><B>Materials and Methods:</B></P><P>Tumor volume and ADC were monitored by T2‐weighted magnetic resonance imaging (MRI) and diffusion‐weighted MRI, respectively, in 18 mice with angiogenesis‐dependent tumors (U118MG) before (day 0) and after 2, 7, 14, and 21 days of administration of the antiangiogenic agent sunitinib maleate (<I>n</I> = 12) or vehicle (<I>n</I> = 6). Percent changes in tumor volume and ADC were calculated and correlations between tumor volume and ADC were evaluated.</P><P><B>Results:</B></P><P>Tumor volume and ADC showed a negative correlation at 69 of the 72 (96%) follow‐up measurements. In the 13 mice with tumor regrowth, ADC started to decrease before (27%) or at the same time (73%) as tumor regrowth. Pretreatment ADC and percent change in ADC change on days 0–2 were similar in mice with positive and negative responses to treatment (0.851 vs. 0.999, 24% vs. 16%). Percent change of ADC showed significant negative correlation with percent change in tumor volume in both the control (<I>r</I> = −0.69) and treated (<I>r</I> = −0.65) groups.</P><P><B>Conclusion:</B></P><P>Percent change in ADC is a reliable and accurate marker for monitoring the effects of antiangiogenic treatment, whereas pretreatment ADC and early changes in ADC (ie, days 0–2) are limited in predicting treatment outcome. J. Magn. Reson. Imaging 2012;35:1430–1436. © 2012 Wiley Periodicals, Inc.</P>
Incidental magnetization transfer effects in multislice brain MRI at 3.0T
Chang, Yongmin,Bae, Sung Jin,Lee, Young Ju,Hwang, Moon Jung,Lee, Sang Heun,Lee, Jongmin,Lee, Sang Kwon,Woo, Seongku RADIOLOGICAL SOCIETY OF NORTH AMERICA INC 2007 JOURNAL OF MAGNETIC RESONANCE IMAGING Vol.25 No.4
<B>Purpose</B><P>To evaluate the effect of incidental magnetization transfer (iMT) in multislice brain imaging at 3.0T.</P><B>Materials and Methods</B><P>The contribution of iMT to multislice brain MRI was evaluated at 3.0T. In 10 normal subjects we obtained multislice fast spin-echo (FSE) MR images using a 16-echo pulse train without an off-resonance MT pulse at 3.0T and 1.5T. We quantified the extent of iMT by calculating the iMT ratio (iMTR).</P><B>Results</B><P>We found that the iMT contrast (iMTC) has a greater effect at 3.0T. As the number of slices increased in multislice FSE imaging, the difference between two field strengths became larger. Compared to WM structures, however, the difference in iMT effect between 1.5T and 3.0T was smaller in the case of GM structures.</P><B>Conclusion</B><P>The iMTC has a greater effect at 3.0T. The strength of the iMT is different for different tissue types and also varies according to the number of slices used. J. Magn. Reson. Imaging 2007. © 2007 Wiley-Liss, Inc.</P>
Cross-sectional Imaging of Splenic Lesions: <i>RadioGraphics Fundamentals | Online Presentation</i>
Lee, Hyo-jae,Kim, Jin Woong,Hong, Jun Hyung,Kim, Gun Su,Shin, Sang Soo,Heo, Suk Hee,Lim, Hyo Soon,Hur, Young Hoe,Seon, Hyun Ju,Jeong, Yong Yeon Radiological Society of North America, Inc. 2018 Radiographics Vol. No.
Lee, H.j.,Kim, J.W.,Hur, Y.H.,Shin, S.S.,Heo, S.H.,Cho, S.B.,Kang, Y.J.,Lim, H.S.,Seon, H.J.,Jeong, Y.Y. RADIOLOGICAL SOCIETY OF NORTH AMERICA INC 2017 JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY Vol.28 No.9
Purpose: To compare therapeutic outcomes of radiofrequency (RF) ablation combined with transcatheter arterial chemoembolization vs surgical resection (SR) for single 2-3 cm hepatocellular carcinoma (HCC). Materials and Methods: Seventy patients underwent combined chemoembolization/RF ablation therapy and 84 underwent SR. Local tumor progression (LTP), intrahepatic distant recurrence (IDR), disease-free survival (DFS), and overall survival (OS) rates, as well as major complications and duration of hospital stay, were compared between groups before and after propensity-score matching. Results: LTP and IDR had developed in 9 (12.9%) and 24 (34.3%) patients in the combined treatment group and in 7 (8.3%) and 24 (28.6%) patients in the SR group (P = .262 and P = .252, respectively). The 1-, 3-, 4-, and 5-year DFS rates were similar between groups (82.6%, 53.2%, 53.2%, and 37.6%, respectively, vs 84.5%, 63.6%, 59.2%, and 52.1%, respectively; P = .278), and 1-, 3-, 4-, and 5-year OS rates were also comparable (94.2%, 81.2%, 74.1%, and 59.4%, respectively, vs 95.2%, 86.3%, 84.0%, and 80.3%, respectively; P = .081). After matching (n = 98), LTP, IDR, DFS, and OS rates were still similar (P = .725, P = .826, P = .484, and P = .578, respectively). Major complication rate was not significantly different (2.9% vs. 6.0%; P = .596); however, after matching, major complication rate was higher in SR group (2.0% vs. 6.1%; P < .001). Hospital stays were significantly longer in the SR group (16.6 +/- 6.7 d vs 8.5 +/- 4.1 d; P < .001). Conclusions: Before and after matching, there were no significant differences in long-term therapeutic outcomes between combined chemoembolization/RF ablation and SR groups. Therefore, combined chemoembolization/RF ablation therapy may be an alternative treatment for single 2-3 cm HCCs.
Data‐driven synthetic MRI FLAIR artifact correction via deep neural network
Ryu, Kanghyun,Nam, Yoonho,Gho, Sung‐,Min,Jang, Jinhee,Lee, Ho‐,Joon,Cha, Jihoon,Baek, Hye Jin,Park, Jiyong,Kim, Dong‐,Hyun RADIOLOGICAL SOCIETY OF NORTH AMERICA INC 2019 Journal of Magnetic Resonance Imaging Vol. No.
<P><B>Background</B></P><P>FLAIR (fluid attenuated inversion recovery) imaging via synthetic MRI methods leads to artifacts in the brain, which can cause diagnostic limitations. The main sources of the artifacts are attributed to the partial volume effect and flow, which are difficult to correct by analytical modeling. In this study, a deep learning (DL)‐based synthetic FLAIR method was developed, which does not require analytical modeling of the signal.</P><P><B>Purpose</B></P><P>To correct artifacts in synthetic FLAIR using a DL method.</P><P><B>Study Type</B></P><P>Retrospective.</P><P><B>Subjects</B></P><P>A total of 80 subjects with clinical indications (60.6 ± 16.7 years, 38 males, 42 females) were divided into three groups: a training set (56 subjects, 62.1 ± 14.8 years, 25 males, 31 females), a validation set (1 subject, 62 years, male), and the testing set (23 subjects, 57.3 ± 20.4 years, 13 males, 10 females).</P><P><B>Field Strength/Sequence</B></P><P>3 T MRI using a multiple‐dynamic multiple‐echo acquisition (MDME) sequence for synthetic MRI and a conventional FLAIR sequence.</P><P><B>Assessment</B></P><P>Normalized root mean square (NRMSE) and structural similarity (SSIM) were computed for uncorrected synthetic FLAIR and DL‐corrected FLAIR. In addition, three neuroradiologists scored the three FLAIR datasets blindly, evaluating image quality and artifacts for sulci/periventricular and intraventricular/cistern space regions.</P><P><B>Statistical Tests</B></P><P>Pairwise Student's <I>t</I>‐tests and a Wilcoxon test were performed.</P><P><B>Results</B></P><P>For quantitative assessment, NRMSE improved from 4.2% to 2.9% (<I>P</I> < 0.0001) and SSIM improved from 0.85 to 0.93 (<I>P</I> < 0.0001). Additionally, NRMSE values significantly improved from 1.58% to 1.26% (<I>P</I> < 0.001), 3.1% to 1.5% (<I>P</I> < 0.0001), and 2.7% to 1.4% (<I>P</I> < 0.0001) in white matter, gray matter, and cerebral spinal fluid (CSF) regions, respectively, when using DL‐corrected FLAIR. For qualitative assessment, DL correction achieved improved overall quality, fewer artifacts in sulci and periventricular regions, and in intraventricular and cistern space regions.</P><P><B>Data Conclusion</B></P><P>The DL approach provides a promising method to correct artifacts in synthetic FLAIR.</P><P><B>Level of Evidence</B>: 4</P><P><B>Technical Efficacy</B>: Stage 1</P><P>J. Magn. Reson. Imaging 2019;50:1413–1423.</P>