• The Korean Journal of Nuclear Medicine
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• v.39 no.2
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• pp.124-132
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• 2005

Cardiac PET emerged as a powerful tool that allowed in vivo quantification of physiologic processes including myocardial perfusion and metabolism, as well as neuronal and receptor function for more than 25 years. Wow PET imaging has been playing an important role in the clinical evaluation of patients with known or suspected ischemic heart disease. This important clinical role is expected to grow with the availability of PET/CT scanner that allow a true integration of structure and function. The objective of this review is to provide an update on the current and future role of PET in clinical cardiology with a special eye on the great opportunities now offered by PET/CT.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.3
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• pp.194-200
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• 2007

Purpose: $^{13}N$-ammonia is a well known radiopharmaceutical for the measurement of a myocardial blood flow (MBF) non-invasively using PET-CT. In this study, we investigated a correlation between MBF obtained from dynamic imaging and myocardial perfusion score (MPS) obtained from static imaging for usefulness of cardiac PET study. Methods: Twelve patients (11 males, 1 female, $57.9{\pm}8.6$ years old) with suspicious coronary artery disease underwent PET-CT scan. Dynamic scans (6 min: $5\;sec\;{\times}\;12,\;10\;sec\;{\times}\;6,\;20\;sec\;{\times}\;3,\;and\;30\;sec\;{\times}\;6$) were initiated simultaneously with bolus injection of 11 MBq/kg $^{13}N-ammonia$ to acquire rest and stress image. Gating image was acquired during 13 minutes continuously. Nine-segment model (4 basal walls, 4 mid walls, and apex) was used for a measurement of MBF. Time activity curve of input function and myocardium was extracted from ROI methods in 9 regions for quantification. The MPS were evaluated using quantitative analysis software. To compare between 20-segment model and 9-segment model, 6 basal segments were excluded and averaged segmental scores were used. Results: There are weak correlation between MBF (rest, 0.18-2.38 ml/min/g; stress, 0.40-4.95 ml/min/g) and MPS (rest 22-91%, stress, 14-90%), however the correlation coefficient between corrected MBF and MPS in rest state was higher than stress state (rest r=0.59; stress r=0.80). As a thickening increased, correlation between MBF and MPS also showed good correlation at each segments. Conclusions: Corrected and translated MPS as its characteristics using $^{13}N$-ammonia showed good correlation with absolute MBF measured by dynamic image in this study. Therefore, we showed MPS is one of good indices which reflect MBF. We anticipate PET-CT could be used as useful tool for evaluation of myocardial function in nuclear cardiac study.

• 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.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.6
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• pp.513-518
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• 2009

Purpose: Integration of the functional information of myocardial perfusion SPECT (MPS) and the morphoanatomical information of coronary CT angiography (CTA) may provide useful additional diagnostic information of the spatial relationship between perfusion defects and coronary stenosis. We studied to know the added value of three dimensional cardiac SPECT/CTA fusion imaging (fusion image) by comparing between fusion image and MPS. Materials and Methods: Forty-eight patients (M:F=26:22, Age: $63.3{\pm}10.4$ years) with a reversible perfusion defect on MPS (adenosine stress/rest SPECT with Tc-99m sestamibi or tetrofosmin) and CTA were included. Fusion images were molded and compared with the findings from the MPS. Invasive coronary angiography served as a reference standard for fusion image and MPS. Results: Total 144 coronary arteries in 48 patients were analyzed; Fusion image yielded the sensitivity, specificity, negative and positive predictive value for the detection of hemodynamically significant stenosis per coronary artery 82.5%, 79.3%, 76.7% and 84.6%, respectively. Respective values for the MPS were 68.8%, 70.7%, 62.1% and 76.4%. And fusion image also could detect more multi-vessel disease. Conclusion: Fused three dimensional volume-rendered SPECT/CTA imaging provides intuitive convincing information about hemodynamic relevant lesion and could improved diagnostic accuracy.

• Progress in Medical Physics
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• v.22 no.4
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• pp.172-177
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• 2011

The purpose of this study was to analyze $^{68}Ga$-BAPEN dynamic PET image in rat myocardium to evaluate potential of this radiotracer as a perfusion imaging agent. Animal PET/CT scan was done in 9 rats during 120 minutes. Especially we synthesized $^{68}Ga$-BAPEN with kit which is simple and low cost method. PET images showed the in vivo dynamic distribution of $^{68}Ga$-BAPEN in the chest region of rats. Initially $^{68}Ga$-BAPEN PET images showed aorta and liver activities and a few minutes later, $^{68}Ga$-BAPEN moved to myocardium. Regions of interest were drawn on myocardium, liver, lung and blood pool. Time-activity curves showed significant uptake of $^{68}Ga$-BAPEN in myocardium. The contrast ratios of myocardial to blood pool, lung and liver at 60 minutes after injection were 1.66, 2.82 and 0.60. To estimate accurate kinetic parameters, 60 minutes after injection was required to PET scan as myocardium image contrast ratios reached to constant values. As a result, $^{68}Ga$-BAPEN would be suitable radiotracer for PET which can applied to diagnosis of myocardial perfusion diseases after further preclinical and clinical investigations.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.2
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• pp.98-111
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• 2008

This review introduces advances in clinical and pre-clinical single photon emission computed tomography (SPECT) and positron emission tomography (PET) providing noninvasive functional images of biological processes. Development of new collimation techniques such as multi-pinhole and slit-slat collimators permits the improvement of system spatial resolution and sensitivity of SPECT. Application specific SPECT systems using smaller and compact solid-state detector have been customized for myocardial perfusion imaging with higher performance. Combined SPECT/CT providing improved diagnostic and functional capabilities has been introduced. Advances in PET and CT instrumentation have been incorporated in the PET/CT design that provide the metabolic information from PET superimposed on the anatomic information from CT. Improvements in the sensitivity of PET have achieved by the fully 3D acquisition with no septa and the extension of axial field-of-view. With the development of faster scintillation crystals and electronics, time-of-flight (TOF) PET is now commercially available allowing the increase in the signal-to-noise ratio by incorporation of TOF information into the PET reconstruction process. Hybrid PET/SPECT/CT systems has become commercially available for molecular imaging in small animal models. The pre-clinical systems have improved spatial resolution using depth-of-interaction measurement and new collimators. The recent works on solid state detector and dual modality nuclear medicine instrumentations incorporating MRI and optical imagers will also be discussed.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.2
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• pp.78-83
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• 2013

Purpose: SPECT/CT, a combination of SPECT and CT, is capable of expressing the results of attenuation correction on images biased by automatic program. As a result, this research evaluates the usefulness of images with CT attenuation correction, using various phantoms and images of patients. Materials and Methods: From July of 2012 to September of 2012, this research was conducted on the contrast, spatial resolution, and images of patients. We studied the contrast with IEC body phantom and Jaszczak phantom, while the spatial resolution was evaluated with NEMA triple line phantom. Further, a comparative study was carried out on the quality of the images, on the difference between the images before and after the CT attenuation correction. Results: Compared the differences between the contrast before and after the CT attenuation correction in IEC body phantom. The contrast was improved by 33.6% at minimum, 89.8% at maximum. In case of Jaszczak Phantom, the contrast was enhanced by 9.9% at minimum, 27.8% at maximum. In NEMA Triple line phantom, the resolution was raised by 4.5% in average: 4.4% in horizontal, 4.5% in vertical. In Anthropomorphic Torso Phantom, the perfusion score of the interior wall with the most severe attenuation was measured to be 29.4%. In the experiment carried out on myocardial perfusion SPECT/CT patients, 9% improvement was discovered in the interior wall, where the most dramatic attenuation occurred, after the CT attenuation correction. Conclusion: SPECT/CT proved its clinical usefulness by enabling the acquisition of images with enhanced contrast and spatial resolution compare to the ones resulted from SPECT.

• The Korean Journal of Nuclear Medicine
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• v.38 no.3
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• pp.268-271
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• 2004

A 43-year-old man was presented with persistent headache for two weeks. 72 weighted MR imaging showed high signal intensity with surrounding edema in the left frontal lobe. These findings were considered with intracranial tumor such as glioma or metastasis. Tc-99m tetrofosmin SPECT showed focal radiotracer accumulation in the left frontal lobe. The operative specimen contained cerebral infarction with organizing leptomeningeal hematoma by pathologist. Another 73-year-old man was hospitalized for chronic headache. Initial CT showed ill-defined hypodensity with mass effect in the right parietal lobe. Tc-99m tetrofosmin SPECT showed focal radiotracer uptake in the right parietal lobe. These findings were considered with low-grade glioma or infarction. Follow-up CT after 5 months showed slightly decreased in size of low density in the right parietal lobe, and cerebral infarction is more likely than others. Tc-99m tetrofosmin has been proposed as a cardiotracer of myocardial perfusion imaging and an oncotropic radiotracer. Tc-99m tetrofosmin SPECT image provides a better attractive alternative agent than T1-201 as a tumor-imaging agent, with characteristics such as high-energy flux, short half-life, favorable biodistribution, dosimetry and lower background radioactivity. We have keep in mind on the analysis of Tc-99m tetrofomin imaging when cerebral infarction is being differentiated from brain tumor.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.86-90
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• 2012

Purpose: Quantification of myocardial blood flow (MBF) using dynamic PET imaging has the potential to assess coronary artery disease. Rb-82 plays a key role in the clinical assessment of myocardial perfusion using PET. However, MBF could be overestimated due to the underestimation of left ventricular input function in the beginning of the acquisition when the scanner has non-linearity between count rate and activity concentration due to the scanner dead-time. Therefore, in this study, we evaluated the count rate linearity as a function of the activity concentration in PET data acquired in list mode. Materials & methods: A cylindrical phantom (diameter, 12 cm length, 10.5 cm) filled with 296 MBq F-18 solution and 800 mL of water was used to estimate the linearity of the Biograph 40 True Point PET/CT scanner. PET data was acquired with 10 min per frame of 1 bed duration in list mode for different activity concentration levels in 7 half-lives. The images were reconstructed by OSEM and FBP algorithms. Prompt, net true and random counts of PET data according to the activity concentration were measured. Total and background counts were measured by drawing ROI on the phantom images and linearity was measured using background correction. Results: The prompt count rates in list mode were linearly increased proportionally to the activity concentration. At a low activity concentration (<30 kBq/mL), the prompt net true and random count rates were increased with the activity concentration. At a high activity concentration (>30 kBq/mL), the increasing rate of the prompt net true rates was slightly decreased while the increasing rate of random counts was increased. There was no difference in the image intensity linearity between OSEM and FBP algorithms. Conclusion: The Biograph 40 True Point PET/CT scanner showed good linearity of count rate even at a high activity concentration (~370 kBq/mL).The result indicates that the scanner is useful for the quantitative analysis of data in heart dynamic studies using Rb-82, N-13, O-15 and F-18.

• Tuberculosis and Respiratory Diseases
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• v.43 no.1
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• pp.54-62
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• 1996

Background: $^{99m}Tc$ MIBI(Methoxyisobutylisonitrile complex), a member of the isonitrile class of coordination compounds, is a lipophilic cation presently under investigation for clinical use as myocardial perfusion imaging agent and is widely used to detect myocardial infarction. Preliminary reports indicate that $T_1$-201 accumulate in human neoplasm and several authors reported $^{99m}Tc$ MIBI may also localized in primary malignant tumor and metastatic deposits from lung cancer. We evaluated the uptake of $^{99m}Tc$ MIBI in lung cancer and localization of mediastinal and other site metastasis, and compared the benign lesion of the lung. Method: Thirty four patients of lung cancer and ten patients of benign lung lesion were studied with chest CT and $^{99m}Tc$ MIBI Lung SPECT. $^{99m}Tc$ MIBI uptake ratio was assessed by TR/NL(Lung lesion/ Normal area), HT/NL (Heart/Normal area) and HT/TR(Heart/Lung lesion). Results: 1) All lung cancer patients showed increased uptakes of $^{99m}Tc$ MIBI in malignant lung lesion and Tc-99m MIBI uptake was also increased in mediastinal and lymph node metastasis except two cases. 2) There was significant different ratio of TR/NL between malignant and benign lesion, $3.79{\pm}1.82$ and $1.67{\pm}0.63$ on planar images, respectively(p<0.001). 3) There was no significant difference of $^{99m}Tc$ MIBI uptake ratio between squamous cell carcinoma, small cell carcinoma and adeno carcinoma($3.64{\pm}1.66$, $3.57{\pm}0.72$, $4.31{\pm}2.28$ respectively). Conclusion: $^{99m}Tc$ MIBI lung SPECT was useful in the localization of tumor and mediastinal or other site metastatic lesion in lung cancer and also in the differential diagnosis between benign and malignant lesion.