• Korean Journal of Radiology
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• v.22 no.3
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• pp.308-323
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• 2021

An increasing number of adult congenital heart disease (ACHD) patients continue to require life-long diagnostic imaging surveillance using cardiac CT and MRI. These patients typically exhibit a large spectrum of unique anatomical and functional changes resulting from either single- or multi-stage palliation and surgical correction. Radiologists involved in the diagnostic task of monitoring treatment effects and detecting potential complications should be familiar with common cardiac CT and MRI findings observed in patients with repaired complex ACHD. This review article highlights the contemporary role of CT and MRI in three commonly encountered repaired ACHD: repaired tetralogy of Fallot, transposition of the great arteries after arterial switch operation, and functional single ventricle after Fontan operation.

• Korean Journal of Radiology
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• v.21 no.12
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• pp.1305-1316
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• 2020

In approximately 10% of patients with acute myocardial infarction (MI), angiography does not reveal an obstructive coronary stenosis. This is known as myocardial infarction with non-obstructive coronary arteries (MINOCA), which has complex and multifactorial causes. However, this term can be confusing and open to dual interpretation, because MINOCA is also used to describe patients with acute myocardial injury caused by ischemia-related myocardial necrosis. Therefore, with regards to this specific context of MINOCA, the generic term for MINOCA should be replaced with troponin-positive with non-obstructive coronary arteries (TpNOCA). The causes of TpNOCA can be subcategorized into epicardial coronary (causes of MINOCA), myocardial, and extracardiac disorders. Cardiac magnetic resonance imaging can confirm MI and differentiate various myocardial causes, while cardiac computed tomography is useful to diagnose the extracardiac causes.

• The Journal of the Korea Contents Association
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• v.21 no.2
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• pp.437-444
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• 2021

The aim of this study was to compare the cardiac CT and cardiac MRI in calculating and correcting the left ventricle ejection fraction by analyzing the physical and temporal resolution for reducing the misdiagnosis rate. One hundred thirty-eight patients with aortic value regurgitation who underwent both cardiac CT and cardiac MRI were analyzed. Left ventricle ejection fractions calculated from each exam were corrected based on the physical and temporal resolution differences and the reliability test evaluated whether the misdiagnosis rate of cardiac CT was improved after the correction. As a result of the study, the misdiagnosis rate of cardiac CT ejection fraction before correcting the difference in physical and temporal resolution was 38.4%(53 persons). In addition, it can be seen that the corrected cardiac CT ejection fraction confirmed in the Bland-Altman plot was highly consistent with the ejection fraction of cardiac MRI. In conclusion, as the cardiac CT is less well suited for measuring ejection fraction, physical characteristics and the time resolution correction using cardiac MRI is needed and the misdiagnosis rate after correction decreased to 14.5%(20 persons). Therefore, this study appears more appropriate for better prediction of ejection fraction and clinical utility.

• Journal of Cardiovascular Imaging
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• v.31 no.2
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• pp.121-123
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• 2023

• Investigative Magnetic Resonance Imaging
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• v.20 no.2
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• pp.132-135
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• 2016

We report the case of a 43-year-old male with both giant left atrial appendage (LAA) aneurysm and drug-refractory atrial fibrillation (AF). The patient was treated with percutaneous electrical isolation of cardiac arrhythmogenic substrate, and has been free of AF symptom over one year. Although the surgical resection of giant LAA aneurysm is mostly used to prevent systemic thromboembolism, we have performed follow-up of the giant LAA aneurysm using cardiac magnetic resonance (CMR) imaging and transesophageal echocardiography (TEE) after the successful catheter ablation of refractory AF. At one-year follow-up CMR, the giant LAA aneurysm showed remarkable enlargement as well as decreased contractility. Additionally, one-year follow-up TEE showed spontaneous echo contrast as an indicator of blood stasis in the giant LAA aneurysm. Those findings of giant LAA aneurysm suggest that the risk of thromboembolism may be high despite termination of AF.

• Investigative Magnetic Resonance Imaging
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• v.7 no.2
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• pp.100-107
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• 2003

Purpose : To assess the usefulness of cardiac MR imaging (MRI) in the diagnosis of acute myocardial infarction and in the assessment of myocardial viability in comparision with T1-201 SPECT. Materials and Methods : We retrospectively studied 17 patients who complained of chest pain and dyspnea with cardiac MRI . The patients were evaluated for the presence or absence of high signal intensity on T2-weighted image (T2wI), abnormal wall motion on 2D-FIESTA, perfusion defect on Gd-DTPA enhanced T1WI, and delayed myocardial enhancement on 15-minutes delay Gd-DTPA enhanced T1WI. The results were correlated with the images on T1-201 SPECT, taken at rest and stress, through which reversibility of perfusion defect was assessed. Results : Both cardiac MRI and T1-201 SPECT proved to be useful methods for diagnosing acute myocardial infarction. In order of decreasing correspondence, T2WI, T1-201 SPECT, delayed enhancement study, and wall motion images all showed significant statistical correlation with the clinical diagnosis of myocardial infarction. Perfusion MRI, on the other hand, showed no significant statistical difference was found between T1-201 SPECT and cardiac MRI. The results on T2WI showed high accordance with those on Tl-201 SPECT, while delayed myocardial enhancement and wall motion studies showed no agreement with Tl-201 SPECT. Conclusion : Cardiac MRI is useful method for diagnosis of acute myocardiac infarction. With respect to the assessment of myocardial viability, the results obtained on cardiac MRI showed high agreement with those on Tl-201 SPECT. However, further study is necessary at this point for standardization and establishment of the methods for assessing myocardial viability on cardiac MRI.

• Investigative Magnetic Resonance Imaging
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• v.25 no.1
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• pp.10-22
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• 2021

Purpose: To overcome the difficulty in building a large data set with a high-quality in medical imaging, a concept of 'blended-transfer learning' (BTL) using a combination of both source data and target data is proposed for the target task. Materials and Methods: Source and target tasks were defined as training of the source and target networks to reconstruct cardiac CINE images from undersampled data, respectively. In transfer learning (TL), the entire neural network (NN) or some parts of the NN after conducting a source task using an open data set was adopted in the target network as the initial network to improve the learning speed and the performance of the target task. Using BTL, an NN effectively learned the target data while preserving knowledge from the source data to the maximum extent possible. The ratio of the source data to the target data was reduced stepwise from 1 in the initial stage to 0 in the final stage. Results: NN that performed BTL showed an improved performance compared to those that performed TL or standalone learning (SL). Generalization of NN was also better achieved. The learning curve was evaluated using normalized mean square error (NMSE) of reconstructed images for both target data and source data. BTL reduced the learning time by 1.25 to 100 times and provided better image quality. Its NMSE was 3% to 8% lower than with SL. Conclusion: The NN that performed the proposed BTL showed the best performance in terms of learning speed and learning curve. It also showed the highest reconstructed-image quality with the lowest NMSE for the test data set. Thus, BTL is an effective way of learning for NNs in the medical-imaging domain where both quality and quantity of data are always limited.

• The Korean Journal of Nuclear Medicine
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• v.27 no.2
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• pp.195-202
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• 1993

$^{123}Iodine$-metaiodobenzylguanidine (MIBG) which is a norepinephrine analogue, can be used to evaluate the sympathetic innervation of the heart. In this study, cardiac imaging with $^{123}I-MIBG$ was performed in patients with 9 dilated cardiomyopathy, 2 ischemic cardiomyopathy and 1 acute myocardial infarction to evaluate the sympathetic nervous function. $^{123}I-MIBG$ imaging showed multifocal defects (8), diffuse defect (2), near non-visualization (2). The defects of MIBG scans were found to be larger and more severe on 4 hours image than 30 minutes. Heart to lung, heart to mediastinum ratios were decreased at 4 hours than those at 30 minutes. Measured LVEF values were not correlated with the severity of MIBG uptake. $^{99m}Tc-MIBI$ imaging was also performed in all patients to find the relationship with $^{123}I-MIBG$ scan. $^{99m}Tc-MIBI$ scan showed multifocal defects in 9 patients, diffuse defects in 1 patient and no defect in 2 patients. The defects are similar in size, severity and extent, but more larger and severe on $^{123}I-MIBG$ imaging. Therefore, cardiac $^{123}I-MIBG$ imaging is a useful method to evaluate the sympathetic nervous function in cardiomyopathy.

• Journal of Yeungnam Medical Science
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• v.34 no.2
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• pp.238-241
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• 2017

Background: We investigated the difference in right ventricle (RV) volume and ejection fraction (EF) according to the pulmonary valve (PV) annular extension technique during Tetralogy of Fallot (TOF) total correction. Methods: We divided patients who underwent the procedure from 1993 to 2003 into two groups according to PV extension technique (group I: PV annular extension, group II: no PV annular extension) during TOF total correction. We then analyzed the three segmental (RV inlet, trabecular and outlet) and whole RV volume and EF by cardiac magnetic resonance imaging (MRI). Results: Fourteen patients were included in this study (group I: 10 patients, group II: four patients; male: nine patients, female: five patients). Cardiac MRI was conducted after a 16.1 years TOF total correction follow-up period. There was no statistical difference in RV segmental volume index or EF between groups (all p>0.05). Moreover, the total RV volume index and EF did not differ significantly between groups (all p>0.05). Conclusion: The RV volume and EF of the PV annular extension group did not differ from that of the PV annular extension group. Thus, PV annular preservation technique did not show the surgical advantage compared to PV annular extension technique in this study.

• Korean Journal of Radiology
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• v.24 no.6
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• pp.512-521
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• 2023

Objective: There is increasing recognition that left atrial (LA) strain can be a prognostic marker of various cardiac diseases. However, its prognostic value in acute myocarditis remains unclear. Therefore, this study aimed to evaluate whether cardiovascular magnetic resonance (CMR)-derived parameters of LA strain can predict outcomes in patients with acute myocarditis. Materials and Methods: We retrospectively analyzed the data of 47 consecutive patients (44.2 ± 18.3 years; 29 males) with acute myocarditis who underwent CMR in 13.5 ± 9.7 days (range, 0-31 days) of symptom onset. Various parameters, including feature-tracked CMR-derived LA strain, were measured using CMR. The composite endpoints included cardiac death, heart transplantation, implantable cardioverter-defibrillator or pacemaker implantation, rehospitalization following a cardiac event, atrial fibrillation, or embolic stroke. The Cox regression analysis was performed to identify associations between the variables derived from CMR and the composite endpoints. Results: After a median follow-up of 37 months, 20 of the 47 (42.6%) patients experienced the composite events. In the multivariable Cox regression analysis, LA reservoir and conduit strains were independent predictors of the composite endpoints, with an adjusted hazard ratio per 1% increase of 0.90 (95% confidence interval [CI], 0.84-0.96; P = 0.002) and 0.91 (95% CI, 0.84-0.98; P = 0.013), respectively. Conclusion: LA reservoir and conduit strains derived from CMR are independent predictors of adverse clinical outcomes in patients with acute myocarditis.