• The Korean Journal of Nuclear Medicine
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• v.34 no.3
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• pp.228-233
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• 2000

Purpose: The aim of this study is to better understand the pattern and nature of reverse redistribution (RR) in myocardial perfusion imaging. Materials and Methods: In consecutive 20 acute myocardial infarction (MI) patients, frequency of RR was correlated with that of subendocardial MI that was detected by myocardial contrast echocardiography (MCE). RR was judged to be present when there was more than one grade of worsening in perfusion at 24 hr delayed images compared with the initial rest images. MCE evaluated the significant lack of opacification in the subendocardial myocardium relative to the subepicardial myocardium to suggest the subendocardial MI. Kendall's nonparametric correlation coefficiency was calculated. Results: Concordant cases were 15 of 20 (75%) and correlation was statistically significant (p=0.0285). Conclusion: Our results suggested that RR was correlated with MCE-detected nontransmural MI.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.3
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• pp.229-239
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• 2009

Molecular imaging strives to visualize processes in living subjects at the molecular level. Monitoring biochemical processes at this level will allow us to directly track biological processes and signaling events that lead to pathophysiological abnormalities, and help make personalized medicine a reality by allowing evaluation of therapeutic efficacies on an individual basis. Although most molecular imaging techniques emerged from the field of oncology, they have now gradually gained acceptance by the cardiovascular community. Hence, the availability of dedicated high-resolution small animal imaging systems and specific targeting imaging probes is now enhancing our understanding of cardiovascular diseases and expediting the development of newer therapies. Examples include imaging approaches to evaluate and track the progress of recent genetic and cellular therapies for treatment of myocardial ischemia. Other areas include in vivo monitoring of such key molecular processes as angiogenesis and apoptosis, Cardiovascular molecular imaging is already an important research tool in preclinical experiments. The challenge that lies ahead is to implement these techniques into the clinics so that they may help fulfill the promise of molecular therapies and personalized medicine, as well as to resolve disappointments and controversies surrounding the field.

• Korean Journal of Radiology
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• v.21 no.4
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• pp.462-470
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• 2020

Objective: To demonstrate that human visual illusion can contribute to sub-endocardial dark rim artifact in contrast-enhanced myocardial perfusion magnetic resonance images. Materials and Methods: Numerical phantoms were generated to simulate the first-passage of contrast agent in the heart, and rendered in conventional gray scale as well as in color scale with reduced luminance variation. Cardiac perfusion images were acquired from two healthy volunteers, and were displayed by the same gray and color scales used in the numerical study. Before and after k-space windowing, the left ventricle (LV)-myocardium boarders were analyzed visually and quantitatively through intensity profiles perpendicular the boarders. Results: k-space windowing yielded monotonically decreasing signal intensity near the LV-myocardium boarder in the phantom images, as confirmed by negative finite difference values near the board ranging -1.07 to -0.14. However, the dark band still appears, which is perceived by visual illusion. Dark rim is perceived in the in-vivo images after k-space windowing that removed the quantitative signal dip, suggesting that the perceived dark rim is a visual illusion. The perceived dark rim is stronger at peak LV enhancement than the peak myocardial enhancement, due to the larger intensity difference between LV and myocardium. In both numerical phantom and in-vivo images, the illusory dark band is not visible in the color map due to reduced luminance variation. Conclusion: Visual illusion is another potential cause of dark rim artifact in contrast-enhanced myocardial perfusion MRI as demonstrated by illusory rim perceived in the absence of quantitative intensity undershoot.

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.128-128
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• 1999

• Journal of Cardiovascular Imaging
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• v.31 no.4
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• pp.191-199
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• 2023

BACKGROUND: Assessment of left ventricular (LV) function plays a pivotal role in the management of patients with valvular heart disease, including those caused by rheumatic heart disease. Noninvasive LV pressure-strain loop analysis is emerging as a new echocardiographic method to evaluate global LV systolic function, integrating longitudinal strain by speckle-tracking analysis and noninvasively measured blood pressure to estimate myocardial work. The aim of this study was to characterize global LV myocardial work efficiency in patients with severe rheumatic mitral stenosis (MS) with preserved ejection fraction (EF). METHODS: We retrospectively included adult patients with severe rheumatic MS with preserved EF (> 50%) and sinus rhythm. Healthy individuals without structural heart disease were included as a control group. Global LV myocardial work efficiency was estimated with a proprietary algorithm from speckle-tracking strain analyses, as well as noninvasive blood pressure measurements. RESULTS: A total of 45 individuals with isolated severe rheumatic MS with sinus rhythm and 45 healthy individuals were included. In healthy individuals without structural heart disease, the mean global LV myocardial work efficiency was 96% (standard deviation [SD], 2), Compared with healthy individuals, median global LV myocardial work efficiency was significantly worse in MS patients (89%; SD, 4; p < 0.001) although the LVEF was similar. CONCLUSIONS: Individuals with isolated severe rheumatic MS and preserved EF, had global LV myocardial work efficiencies lower than normal controls.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.4 no.2
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• pp.57-64
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• 2018

${\omega}-[^{18}F]$-Fluorohexadecanoic acid (FHA) has been used for imaging of fatty acid metabolism of myocardium. To increase retention of radiolabeled fatty acid by blocking ${\beta}$-oxidation, methyl branched analogues have been used. In this experiment, we tried to synthesize 18F-labeled ${\alpha}-$, ${\beta}-$ and ${\omega}-FHA$ for imaging of the myocardial fatty acid metabolism. We synthesized ${\alpha}-$, ${\beta}-$ and ${\omega}$-mesylated methyl hexadecanoates and labeled with $^{18}F$ by reacting with $[^{18}F]$TBAF in acetonitrile at $80^{\circ}C$ for 10 min. Methyl ester group was removed by 1 M NaOH at $80^{\circ}C$ for 5 min. The yields of ${\alpha}-[^{18}F]$ and ${\omega}-[^{18}F]FHA$ were 25.5 and 45.5%, respectively [EOS]. However, ${\beta}-[^{18}F]FHA$ was not labeled at all due to a fast elimination reaction. The biodistribution study in ICR-mice showed that ${\omega}-[^{18}F]FHA$ has higher myocardial uptake and lower liver uptake than ${\alpha}-[^{18}F]FHA$. The electron-withdrawing effect of fluorine at ${\alpha}-$ position is believed to be the major factor affecting the biodistribution.

• The Korean Journal of Nuclear Medicine
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• v.39 no.2
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• pp.94-99
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• 2005

Electrocardiogram-gated single photon omission computed tomography (SPECT) provides valuable information in the assessment of both myocardial perfusion and ventricular function. Tl-201 is a suboptimal isotope for gating. Tl-201 images are more blurred compared with Tc-99m tracers due to the increased amount of scattered photons and use of a smooth filter. The average myocardial count densities are approximately one-half those of conventional technetium tracers. However, Tl-201 is still widely used because of its well-established utility for assessing myocardial perfusion, viability and risk stratification. Gated SPECT with Tl-201 enables us to assess both post-stress and rest left ventricular volume and function. Previous studies with gated Tl-201 SPECT measurements of ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV) have shown high correlation with first-pass radionuclide angiography, gated blood pool scan, Tc-99m-MIBI gated SPECT, contrast ventriculography, echocardiography, and 3-dimensional magnetic resonance imaging. However, problems related to these studies include few agreement data of EDV and ESV, use of a reference method that is likely to have the same systemic errors (gated Tc-99m-MIBI SPECT), and other technical factors related to the count density of gated SPECT. With optimization of gated imaging protocols and more validation studies, gated Tl-201 SPECT would be an accurate method to provide perfusion and function information in patients with coronary artery disease.

• Investigative Magnetic Resonance Imaging
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• v.16 no.2
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• pp.189-194
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• 2012

We report a case of cardiac lymphoma in a 40-year-old man, who had a mediastinal mass which was diagnosed as sclerosing mediastinitis pathologically. The mediastinal mass caused right pulmonary arterial stenosis. The patient developed myocardial hypertrophy and echocardiography showed restrictive physiology and severely decreased left ventricle ejection fraction, 6 months later. MRI showed global left ventricular myocardial hypertrophy and diffuse late gadolinium hyperenhancement after administration of contrast material. Thus, non-ischemic cardiomyopathy was suspected on MRI. However, pathology confirmed the myocardial abnormality as lymphoma after myocardial biopsy. Because a basal part of the left ventricle and global subendocardial myocardium were not involved on contrast-enhanced delayed MRI, the MRI abnormalities could be differentiated from amyloidosis and other myocardial diseases. The peculiar non-mass forming diffuse hypertrophy pattern of cardiac lymphoma has not been known in the MRI literature.

• Investigative Magnetic Resonance Imaging
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• v.7 no.2
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• pp.132-136
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• 2003

Purpose : To evaluate the usefulness of breath-hold T2-weighted MR imaging in patients with myocardial infarction. Materials and Methods : We investigated 11 patients with myocardial infarction who shown delayed enhancement on MR imaging. Infarcted myocardium on T2-weighted MR imaging was classified as high, iso, and low signal area comparing with normal myocardium. The intensity and transmural extent of infracted myocardium was also analyzed. On the basis of clinical information, the stage of infracted myocardium on T2-weighted MR imaging was assessed. Results : It was observed high signal area in 12 segments of 5 patients, low in 12 segments of 6 patients on T2-weighted MR imaging. The high signal intensity of infarcted myocardium was shown as $175{\pm}9\%$ comparing with that of the normal myocardium, low signal intensity as $73{\pm}5\%\;(p\;<\;0.05)$. In the evaluation of transmural extent, the high signal areas on T2-weighted MR imaging were larger than infarct area on delayed enhancement imaging $(100\%\;vs.49\%{\pm}17\%)$, whereas low signal areas on T2-weighted MR imaging correlated. High signal area was visualized on T2-weighted MR imaging within 11 days, whereas low-signal area was seen after 7 months. Conclusion : Breath-hold T2-weighted MR imaging is useful in the evaluation of stage as well as edema and fibrous scar in patients with myocardial infarction.

• The Korean Journal of Nuclear Medicine
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• v.39 no.2
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• pp.118-123
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• 2005

Positron emission tomography (PET) serves as a gold standard for noninvasive in vivo measurement of myocardial blood flow (MBF) and coronary flow reserve (CFR). CFR can be defined as the ratio of maximally vasodilated MBF over its basal flow. It is an important parameter for the evaluation of functional severity of coronary stenosis and prognositification in various diseases such as dilated cardiomyopathy. $^{13}NH_3,\;H_2^{15}O,\;^{82}Rb$ are widely used radiopharmaceuticals for measuring MBF and CFR, This review introduces imaging techniques and its clinical utility. Cardiac application or PET and PET/CT is expected to be increased in near future.