• The Korean Journal of Nuclear Medicine
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• v.27 no.2
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• pp.210-217
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• 1993

To compare the myocardial viability in patients suffering from total occlusion of the right coronry artery (RCA) with the angiographic collaterals, intracoronary injection of Thallium-201 (T1-201) was done to 14 coronary artery disease (CAD) patients (pts) with total occlusion of RCA and into four normal subjects for control. All 14 CAD pts had Grade 2 or 3 collateral circulations. There were 14 male and 4 females, and their ages ranged from 31 to 70 years. In nine pts, T1-201 was injected into left main coronary artery (LCA) ($300{\sim}350{\mu}Ci$) to evaluate the myocardial viability of RCA territory through collateral circulations. The remaining five pts received T1-201 into RCA ($200{\sim}250{\mu}Ci$) because two had intraarterial bridging collaterals and three had previous successful PTCA. Planar & SPECT myocardial perfusion images were obtained 30 minutes, and four to five hours after T1-201 injection. Intravenous T1-201 reinjection (six pts) or $^{99m}Tc-MIBI$ (two pts) were also performed in eight CAD pts. Intracoronary myocardial perfusion images were compared with intravenous T1-201 (IV T1-201) images, ECG, and ventriculography. Intracoronary T1-201 images proved to be superior to that of IV T1-201 due to better myocardial to background uptake ratio and more effective in the detection of viable tissue. We also found that perfusion defects were smaller on intracoronary T1-201 images than those on the IV T1-201. All of the 14 CAD pts had either mostly viable myocardium (seven pts) or large area of T1-201 perfusion (seven pts) in RCA territory, however ventriculographic wall motion and ECG did not correlate well with intracoronary myocardial perfusion images. In conclusion, total RCA occlusion patients with well developed collateral circulation had large area of viable myocardial in the corresponding territory.

• The Korean Journal of Nuclear Medicine
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• v.27 no.2
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• pp.223-232
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• 1993

Technetium labeled isonitrile analogues are widely used as myocardial perfusion imaging agents. We synthesized and characterized a new isonitrile compound, ethyl 3-isocyanobutyrate(EIB). Proton and $^{13}C$ NMR spectroscopy and thin layer chromatography with a $C_{18}$ coat was performed. EIB was easily labeled with $^{99m}TcO_4^-$- with sodium dithionite. The labeling efficiency measured by RP-HPLC was over 95%. The labeled product was stable with dilution in normal saline and with prolonged incubation at room temperature. There was no formation of secondary products or free $^{99m}TcO_4^-$. In vivo kinetics study of $^{99m}Tc$ (I) labeled EIB in rabbits showed adequate myocardial uptake, good contrast against lung background, and relatively rapid liver clearance. The heart to lung ratio was over 2.5 and the heart to liver ratio was approximately from 0.4 to 5 at 60 minutes post injection. Hepatic clearance of $^{99m}Tc-MIBI$ was faster ($t_{1/2}$=6 minutes) than that of $^{99m}Tc-MIBI$. In vivo kinetics observed in dog was similar to that in rabbit but there was faster gallbladder filling, and thus lower liver background. SPECT imaging of the canine myocardium showed favorable imaging characteristics. However, biodistribution in mice demonstrated a myocardial % injected dose/organ of less than 0.1%. This was thought to be due to interspecies difference in plasma esterase activity. In human plasma, $^{99m}Tc$ ( I ) labeled EIB was stable for at least 2 hours, without production of secondary products by HPLC. We conclude that ethyl 3-isocyanobutyrate may be a potential new myocardial perfusion imaging agent and deserves further investigation as to its usefulness for clinical use.

• The Korean Journal of Nuclear Medicine
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• v.34 no.5
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• pp.381-392
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• 2000

Purpose: We compared the reproducibility of $^{201}Tl\;and\;^{99m}Tc$-sestamibi (MIBI) gated SPECT measurement of myocardial function using the Germano algorithm Materials and Methods: Gated SPECT acquisition was repeated in the same position in 30 patients who received $^{201}Tl$ and in 26 who received $^{99m}Tc$-MIBI. The quantification of end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF) on $^{201}Tl\;and\;^{99m}Tc$-MIBI gated SPECT was processed independently using Cedars quantitative gated SPECT software. The reproducibility of the assessment of myocardial function on $^{201}Tl$ gated SPECT was compared with that of $^{99m}Tc$-MIBI gated SPECT Results: Correlation between the two measurements for volumes and EF was excellent by the repeated gated SPECT studies of $^{201}Tl$ (r=0.928 to 0.986; p<0.05) and $^{99m}Tc$-MIBI (r=0.979 to 0.997; p<0.05). However, Bland Altman analysis revealed the 95% limits of agreement (2 SD) for volumes and EF were tighter by repeated $^{99m}Tc$-MIBI gated SPECT (EDV: 14.1 ml, ESV: 9.4 ml and EF: 5.5%) than by repeated $^{201}Tl$ gated SPECT (EDV: 24.1 ml, ESV: 18.6 ml and EF: 10.3%). The root mean square (RMS) values of the coefficient of variation (CV) for volumes und EFs were smaller by repeated $^{99m}Tc$-MIBI gated SPECT (EDV: 2.1 ml, ESV 2.7 ml and EF: 2.3%) than by repeated $^{201}Tl$ gated SPECT (EDV: 3.2 ml, ESV: 3.5 ml and EF: 5.2%). Conclusion: $^{99m}Tc$-MIBI provides more reproducible volumes and EF than $^{201}Tl$ on repeated acquisition gated SPECT. $^{99m}Tc$-MIBI gated SPECT is the preferable method for the clinical monitoring of myocardial function.

• The Korean Journal of Nuclear Medicine
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• v.30 no.4
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• pp.493-501
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• 1996

To assess contribution of T1-201 rest-24 hour delay redistribution in detection of viable myocardium, we studied the predictive value of this redistribution in 17 patients who peformed rest-24 hour delay perfusion SPECT before bypass surgery. Regional wall motion was compared with gated SPECT in 10 patients and echocardiography in 7 patients before and after bypass surgery. Rest and 24 hour delayed uptakes were scored from 0 (normal perfusion) to 3 (defect). In rest SPECT, 56 segments showed perfusion decrease. Thirty four segments(61%) improved after surgery and were defined as viable Nineteen(34%) segments had more uptake of T1-201 at 24 hour delay, and the other 37 segments did not. In 81%(25/31) of segments with mildly decreased perfusion, wall motion after bypass surgery improved, 57% (8/14) of segments with severely decreased perfusion improved, and 9%(1/11) of segments with defects improved. In 14 among 19 segments which had more T1-201 uptakes at 24 hour delay, wall motion was improved(positive predictive value of redistribution: 74%). 20 among 37 segments which had persistent decreases in rest-24 hour redistribution improved and 17 did not(negative predictive value: 46%). Segments having severe perfusion decrease or defects showed improved wall motion after surgery in 64%(7/11), if it had redistribution at delay. Segments with either mildly decreased uptake in resting or rest-delayed redistribution showed improved wall motion in 76%(32/42). Among the 14 segments which showed improvement in wall motion, 10 had partial reversibility in stress-rest images and the other 4 had persistent perfusion defects in stress-rest images. These 4 segments were found viable only with rest-24 hour delayed perfusion SPECT. We concluded that rest T1-201 uptake or redistribution at 24 hour delay should be referred as an evidence to warrant postoperative improvement of abnormal wall motion and we could predict myocardial viability with preoperative rest-24 hour delay perfusion SPECT in the segments with rest perfusion decreases.

• The Korean Journal of Nuclear Medicine
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• v.29 no.4
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• pp.473-477
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• 1995

Information about regional wall motion obtained with gated $^{99m}Tc-MIBI$ SPECT was compared in 23 subjects(4 normals) to echocardiography or contrast left ventriculography. Gated SPECT study using 20-30 mCi $^{99m}Tc-MIBI$ were aquired lot 8 frames/RR interval (aqusition time=40min.) and processed with Cine Mode computer protocol. Regional wall motion was assessed by visual analysis. The concordance with echocardiography was 88% and with contrast ventriculography was 78%. We conclude that gated $^{99m}Tc-MIBI$ SPECT was effective in assessing the regional wall motion with the information of regional perfusion in one study.

• Journal of Yeungnam Medical Science
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• v.26 no.1
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• pp.15-23
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• 2009

Constant technological developments in coronary artery disease have contributed to the assessment of both the presence of coronary stenosis and its hemodynamic consequences. Hence, noninvasive imaging helps guide therapeutic decisions by providing complementary information on coronary morphology and on myocardial perfusion and metabolism. This can he done using single photon emission computed tomography (SPECT) or positron emission tomography (PET) and multidetector CT (MDCT). Advances in image-processing software and the advent of SPECT/CT and PET/CT have paved the way for the combination of image datasets from different modalities, giving rise to hybrid imaging. Three dimensional cardiac hybrid imaging helped to confirm hemodynamic significance in many lesions, add new lesions such as left main coronay artery disease, exclude equivocal defects, correct the corresponding arteries to their allocated defects and identify culprit segment. Cardiac hybrid imaging avoids the mental integration of functional and morphologic images and facilitates a comprehensive interpretation of coronaty lesions and their pathophysiologic adequacy by three dimensional display of fused images, and allows the best evaluation of myocardial territories and the coronary-artery branches that serve each territory. This integration of functional and morphological information were feasible to intuitively convincing and might facilitate development of a comprehensive non-invasive assessment of coronary artery disease.

• The Korean Journal of Nuclear Medicine
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• v.38 no.6
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• pp.486-491
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• 2004

Purpose: factor analysis and independent component analysis (ICA) has been used for handling dynamic image sequences. Theoretical advantages of a newly suggested ICA method, ensemble ICA, leaded us to consider applying this method to the analysis of dynamic myocardial $H_2^{15}O$ PET data. In this study, we quantified patients' blood flow using the ensemble ICA method. Materials and Methods: Twenty subjects underwent $H_2^{15}O$ PET scans using ECAT EXACT 47 scanner and myocardial perfusion SPECT using Vertex scanner. After transmission scanning, dynamic emission scans were initiated simultaneously with the injection of $555{\sim}740$ MBq $H_2^{15}O$. Hidden independent components can be extracted from the observed mixed data (PET image) by means of ICA algorithms. Ensemble learning is a variational Bayesian method that provides an analytical approximation to the parameter posterior using a tractable distribution. Variational approximation forms a lower bound on the ensemble likelihood and the maximization of the lower bound is achieved through minimizing the Kullback-Leibler divergence between the true posterior and the variational posterior. In this study, posterior pdf was approximated by a rectified Gaussian distribution to incorporate non-negativity constraint, which is suitable to dynamic images in nuclear medicine. Blood flow was measured in 9 regions - apex, four areas in mid wall, and four areas in base wall. Myocardial perfusion SPECT score and angiography results were compared with the regional blood flow. Results: Major cardiac components were separated successfully by the ensemble ICA method and blood flow could be estimated in 15 among 20 patients. Mean myocardial blood flow was $1.2{\pm}0.40$ ml/min/g in rest, $1.85{\pm}1.12$ ml/min/g in stress state. Blood flow values obtained by an operator in two different occasion were highly correlated (r=0.99). In myocardium component image, the image contrast between left ventricle and myocardium was 1:2.7 in average. Perfusion reserve was significantly different between the regions with and without stenosis detected by the coronary angiography (P<0.01). In 66 segment with stenosis confirmed by angiography, the segments with reversible perfusion decrease in perfusion SPECT showed lower perfusion reserve values in $H_2^{15}O$ PET. Conclusions: Myocardial blood flow could be estimated using an ICA method with ensemble learning. We suggest that the ensemble ICA incorporating non-negative constraint is a feasible method to handle dynamic image sequence obtained by the nuclear medicine techniques.

• The Korean Journal of Nuclear Medicine
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• v.30 no.4
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• pp.502-506
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• 1996

Tc-99m myocardial perfusion agents such as Tc-99m sestamibi or Tc-99m tetrofosmin has advantages over T1-201 for myocardial perfusion scan fuck as low attenuation and easy availability. However, Tc-99m agents do not redistribute so they need to be given T times, namely after stress and at rest. To evaluate whether rest image is needed in patients showing normal stress image, 43 patients who underwent both myocardial perfusion scan and coronary angiography and showed normal stress images were evaluated. Findings of rest images of them were evaluated whether they change the diagnosis or treatment plans. Among 43 patients who showed normal stress myocardial perfusion imaging, 31 (72.1%) showed no additional informations. However, among 5 patients with vasospastic angina 4 (80%) showed abnormal rest images in spite of normal stress images. So, when vasospastic angina is suspected clinically, rest image could be helpful in identifying patients with coronary vasospasm. In conclusion, rest myocardial perfusion images were not helpful in 72.1 % of patients with angina when stress images were normal. In only exception was those with vasospastic angina.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.3
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• pp.159-164
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• 2009

Coronary artery disease is on the rise over the world. Myocardial perfusion SPECT is a well established technique to detect coronary artery disease and to assess left ventricular function. In addition, it has the unique ability to predict the prognosis of the patients. Moreover, the application of ECC-gated images provided the quantitatve data and improved the accuracy. This approach has been proved to be cost-effective and suitable for the emerging economies as well as developed countries. However, the utilization of nuclear cardiology procedures vary widely considering the different countries and region of the world. Korea exits 2-3 times less utilization than Japan, and 20 times than the United States. Recently, with the emerging of new technology, namely cardiac CT, cardiac MR and stress echocardiography, the clinical usefulness of nuclear cardiology has been called in question and its role has been redefined. For the proper promotion of nuclear cardiology, special educations should be conducted since the nuclear cardiology has the contact points between nuclear medicine and cardiology. Several innovations are in horizon which will impact the diagnostic accuracy as well as imaging time and cost savings. Development of new tracers, gamma camera technology and hybrid systems will open the new avenue in cardiac imaging. The future of nuclear cardiology based on molecular imaging is very exciting. The newly defined biologic targets involving atherosclerosis and vascular vulnerability will allow the answers for the key clinical questions. Hybrid techniques including SPECT/CT indicate the direction in which clinical nuclear cardiology may be headed in the immediate future. To what extent nuclear cardiology will be passively absorbed by other modalities, or will actively incorporate other modalities, is up to the present and next generation of nuclear cardiologists.

• The Korean Journal of Nuclear Medicine Technology
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• v.23 no.1
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• pp.75-79
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• 2019

Purpose Cadmium-zinc-telluride (CZT) camera with semiconductor detector is capable of dynamic myocardial perfusion SPECT for coronary flow reserve (CFR). Image acquisition with the heart positioned within 2 cm in the center of the quality field of view (QFOV) is recommended because the CZT detector based on focused multi-pinhole collimators and is stationary gantry without rotation. The aim of this study was to investigate the optimal method for measuring position of the heart within the center of the QFOV when performing dynamic myocardial perfusion SPECT with the Discovery NM 530c camera. Materials and Methods From June to September 2018, 45 patients were subject to dynamic myocardial perfusion SPECT with D530c. For accurate heart positioning, the patient's heart was scanned with a mobile ultrasound and marked at the top of the probe where the mitral valve (MV) was visible in the parasternal long-axis view (PLAX). And, the marked point on the patient's body matched with the reference point indicated CZT detector in dynamic stress. The heart was positioned to be in the center of the QFOV in rest. The coordinates of dynamic stress and rest were compared statistically. Results The coordinates of the dynamic stress using mobile ultrasound and those taken of the rest were recorded for comparative analysis with regard to the position of the couch and analyzed. There were no statistically significant differences in the coordinates of Table in & out, Table up & down, and Detector in & out (P > 0.05). The difference in distance between the 2 groups was measured at $0.25{\pm}1.00$, $0.24{\pm}0.96$ and $0.25{\pm}0.82cm$ respectively, with no difference greater than 2 cm in all categories. Conclusion The position of the heart taken using mobile ultrasound did not differ significantly from that of the center of the QFOV. Therefore, The use of mobile ultrasound in dynamic stress will help to select the correct position of the heart, which will be effective in clinical diagnosis by minimizing the image quality improvement and the patient's exposure to radiation.