• 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.

• The Korean Journal of Nuclear Medicine
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• v.34 no.3
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• pp.199-206
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• 2000

Purpose: Myocardial perfusion scintigraphy is a useful technique to diagnose and to predict prognosis in patients with suspected or known coronary artery disease. The purpose of the present study is to evaluate the prognostic value of normal exercise $^{99m}Tc$-MIBI myocardial perfusion single photon emission computed tomography (SPECT) and to analyze results with regard to those of exercise electrocardiography or coronary angiography. Materials and Methods: We evaluated 301 patients (mean age $52{\pm}10$ years, 166 males and 135 females) with normal exercise $^{99m}Tc$-MIBI myocardial perfusion SPECT performed for suspected coronary artery disease. Subject were evaluated for cardiac events and followed for 8-55 months (mean $19{\pm}10$ months) after imaging. Results: During the follow-up period, there was no cardiac death but only one non-fatal myocardial infarction (event rate 0.21% per year). In addition, only one patient underwent coronary revascularization. There was no significant difference in cardiac event rate between patients with positive (n=27) and negative (n=235) exercise electrocardiography (p:NS). There was no cardiac event in 17 patients who underwent coronary angiography (4 patients with >50% luminal narrowing, 2 patients with vasospasm and 11 patients with no significant lesion). Conclusion: Patients with normal exercise $^{99m}Tc$-MIBI myocardial perfusion SPECT has a very low risk for cardiac events regardless of exercise electrocardiographic and coronary angiographic findings.

• The Korean Journal of Nuclear Medicine
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• v.29 no.1
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• pp.41-47
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• 1995

Tc-99m-MIBI(Sestamibi) myocardial SPECT along with T1-201 tomographic imaging has demonstrated wide application and high image qualify sufficient for the diagnosis of myocardial perfusion defect, which consequently reflects regional myocardial blood flow, The qualitative values of myocardial SPECT with Tc-99m-MIBI as well as the quantitative cases depend in some degree on the reconstruction techniques of multiple projections. Filtered backprojection(FBP) is the common standard for reconstruction rather than the complicated and time-consuming arithmetic methods. In FBP it Is known that the distribution of radioactivity in reconstructed transverse slices varies with the selected filter parameters such as cutoff frequencies and order(Butterworth case). The cutoff frequencies basically remove and decrease the true radioactive distribution and alter the pixel counts, which lead to underestimation of true counts in specific myocardial regions. In this study, we have investigated the effect of cutoff frequencies of reconstruction filter on the artifactually induced perfusion defects, which are often demonstrated near inferior and/or inferoseptal cardiac walls due to the intense hepatic uptake of Tc-99m-MIBI. A computerized method for identifying the relative degree of artifactual perfusion defect and for comparing those degrees along with the relative amount of hepatic uptake to myocardium was developed and patient images were studied to observe the quantitative degree of underestimation of myocardial perfusion, and to propose some reasonable thresh-old of cutoff frequency in the diagnosis of perfusion defect quantitatively. We concluded that from the quantitative viewpoint cutoff frequencies may be used as high as possible with the sacrifice of homogeneity of image quality, and those frequencies lower than the common 0.3 Nyquist frequency would reveal severe degradation of radio-active distribution near inferior and/or Inferoseptal myocardium when applying Butterworth or low pass filter.

• The Korean Journal of Nuclear Medicine Technology
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• v.23 no.2
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• pp.13-19
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• 2019

Purpose Tc-99m HMPAO is widely used radiopharmaceutical for brain perfusion SPECT. Tc-99m HMPAO is chemically unstable and is liable to show deterioration of labeling efficiency due to high incidence of secondary Tc-99m HMPAO complex, free pertechnetate and reduced-hydrolyzed Tc-99m. In this study, we investigated whether sialogogues administration could reduce the impurities of Tc-99m HMPAO. Materials and Methods In thirty subjects(20 male and 10 female, age range 19~89 years, mean age $60.7{\pm}14.5years$), brain perfusion SPECT were performed at basal and citric acid stimulation states consecutively after injection of 555 MBq of Tc-99m HMPAO. In the salivary glands, the uptake coefficient was calculated using Siemens processing program. Statistical comparison between before and after the citric acid stimulation performed paired t-test. P value less than 0.05 was regarded as statistically significant. Results Salivary glands uptake was $12900{\pm}3101$ counts in basal and $10677{\pm}2742$ counts in citric acid stimulation states. Unnecessary impurities in the body is much decreased after citric acid administration(t=10.78, P<0.05). The image quality was much improved after administration of citric acid and the regional cerebral perfusion was clearly from demarcated the background. Conclusion The impurity is distributed throughout the body particularly in the salivary glands and nasal mucosa when Tc-99m HMPAO brain perfusion SPECT is performed. If this impurities is not removed, the quality of the image may deteriorate, resulting in errors in visual evaluation. The use of sialogogues could be helpful for decreasing unnecessary impurities in the body.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.279-282
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• 1996

Sequential brain SPECT imaging has been used to assess the cerebral perfusion reserve(CPR) in cerebrovascular diseases(CVD). We have realized a parametric images of CPR using normalized difference ratio and deadtime correction. For the anatomical localization of CPR, the parametric images were registered to the contours of the cerebral regions using optimal threshold method. The parametric imags reflected the CPR more reliably and distinctively. We conclude that the qunatitative estimation of CPR using normalized difference ratio image could be useful for the diagnosis and assessment of postoperative prognosis in CVD.

• Journal of Chest Surgery
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• v.47 no.5
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• pp.465-467
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• 2014

We present a patient who developed recurrent angina after coronary artery bypass grafting (CABG). Myocardial single-photon emission computed tomography (SPECT) demonstrated deterioration in the myocardial perfusion, and coronary angiography revealed an overgrown side branch of the grafted left internal thoracic artery (ITA); otherwise, there were no significant changes compared with previous imaging studies obtained after the CABG. After percutaneous embolization of the grafted left ITA side branch, the angina was resolved and myocardial SPECT showed improved perfusion.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.3-7
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• 2012

Purpose : In myocardial perfusion SPECT, the type of orbit (circular vs. body contouring) that affect the image quality is still on the debate. Presently in the nuclear medicine field, the body contouring orbit acquisition is widely used to improve the image quality on the myocardial perfusion SPECT. But in case of body contouring acquisition using the vertical method with dual detect machine, there is a tendency of increasing the radius. In this research, we compared body contouring orbit acquisition with circular orbit acquisition, so we suggest ideal method that reduces the radius for improving image quality. Materials and Methods : Phantom and clinical studies were performed. The anthropomorphic torso phantom was made on equally with counts from patient's body. The study was performed under six different conditions. To compare image quality according to the radius, we increased radius sequentially per step during circular orbit acquisition. On the other hand, sensors that protect a collision and reduce the radius automatically were used to acquire image during body contouring orbit acquisition. So we compared FWHM value of apex. In clinical studies, we analyzed the 40 patients who were examined by Tl-201 gated myocardial perfusion SPECT in department of nuclear medicine at Asan Medical Center in August 2011. To acknowledge the differences according to the radius, we acquired the results two times using circular orbit acquisition and body contouring orbit acquisition. Results : In phantom study, we analyzed that increase of radius resulted in changes of FWHM value. It was 5.41, 6.24, 6.33, 6.42, 6.93 mm. On the other hand, using the body contouring orbit acquisition, FWHM value was 6.23 mm. In clinical study, difference of average radius between two methods was 2.5 cm (circular orbit acquisition was more close to patients). Conclusion : Through the experiments using Anthropomorphic torso phantom and patients data, we found that FWHM value of circular orbit acquisition was lower than body contouring orbit acquisition. As a result, if the difference of average radius exists approximately 3 cm, circular orbit type acquisition is better than body contouring type acquisition. But clinical investigation is only aimed to average radius, so it needs more investigation in comparison of patient's image.

• The Korean Journal of Nuclear Medicine
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• v.39 no.3
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• pp.151-162
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• 2005

Hemangioma is the most common benign tumor of the liver, with a prevalence estimated as high as 7%. Tc-99m red blood cell (RBC) hepatic blood pool scan with single photon omission computed tomography (SPECT) imaging is extremely useful for the confirmation or exclusion of hepatic hemangiomas. The classic finding of absent or decreased perfusion and increased blood pooling ("perfusion/blood pool mismatch") is the key diagnostic element in the diagnosis of hemangiomas. The combination of early arterial flow and delayed blood pooling ("perfusion/blood pool match") is shown uncommonly. In giant hemangioma, filling with radioactivity appears first in the periphery, with progressive central fill-in on sequential RBC blood pool scan. However, the reverse filling pattern, which begins first in the center with progressive peripheral filling, is also rarely seen. Studies with false-positive blood pooling have been reported infrequently in nonhemangiomas, including hemangiosarcoma, hepatocellular carcinoma, hepatic adenoma, and metastatic carcinomas (adenocarcinoma of the colon, small cell carcinoma of the lung, neruroendocrine carcinoma). False-negative results have been also reported rarely except for small hemagniomas that are below the limits of spatial resolution of gamma camera.

• The Korean Journal of Nuclear Medicine
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• v.30 no.1
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• pp.112-117
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• 1996

Objective: Standard stress/rest Tc-99m MIBI and T1-201 myocardial perfusion study have some limitations such as stress/rest image overlap for Tc-99m-MIBI, low energy for T1-201 and long period of study time for two separate studies. Separate acquisition rest T1-201/stress Tc-99m MIBI dual isotope study is a potentially efficient myocardial perfusion imaging protocol that combines the high resolution of Tc-99m for stress perfusion assessment and T1-201 for viability assessment. This study assessed the usefulness and diagnostic accuracy for this new approach. Methods: We tried to evaluate sensitivity and specificity of dual isotope separate acquisition protocol in 67 patients. Immediately after resting T1-201 SPECT data was acquired, dipyridamole stress Tc-99m MIBI myocardial perfusion study was performed. Visual analysis was carried out qualitatively with 0 to 3 scoring system for 17 segments of left ventricle in the reconstructed horizontal long axis and short axis slices. Results: Total study was completed within 3 hours. In angiographic correlation, dual isotope SPECT demonstrated high sensitivity(85%) and in a small group of patients, high specificity was also observed (100%). Conclusion: Combined thallium-201/stress Tc-99m MIBI SPECT displayed similiar diagnostic accuracy to protocol using stress/rest Tc-99m MIBI SPECT. This protocol was completed in shorter period than the previous protocols and therefore enhance laboratory throughput and patients convenience.

• The Korean Journal of Nuclear Medicine
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• v.38 no.6
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• pp.540-542
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• 2004

Although artifacts in tomographic imaging can arise from a number of sources, this case presents an artifact caused by using inadequate acquisition parameters which do not match the collimator with which a camera equipped in Tc-99m ECD brain SPECT. Whenever the collimator in tomographic studies is changed, we should take care to use suitable parameters of acquisition protocol according to the collimator with which a camera is fitted. Other ways to prevent an error of this type is to use a point source.