[en] Serum thyroglobulin measurement and I-131 whole-body scintigraphy (WBS) are well-established methods for the detection of recurrence in the follow-up of patients with thyroid carcinoma. However, inconsistent results are observed frequently, and these two methods are not always able to detect recurrence. In some patients, serum thyroglobulin level is elevated but the WBS is negative, because the recurrent tumor is too small and below the sensitivity of the diagnostic scan, or there is a dissociation between thyroglobulin synthesis and the iodine trapping mechanism. In such cases, various nuclear imaging methods including Tl-201, Tc-99m-sestamibi, and F-18-FDG PET can be used besides anatomical imaging methods. Among them, FDG PET localizes recurrent lesions in WBS-negative thyroid carcinoma with high accuracy. Several studies have suggested that empirical high-dose I-131 therapy resulted in a high rate of visualization in post-therapy scans with evidence of subsequent improvement. An important question is when to operate on patients with recurrent tumor. We believe that surgical removal is the best means of treatment for patients with localized persistent tumor, despite the high-dose I-131 therapy, with tumor in thyroid remnant, and with isolated recurrence in the lymph node, lung or bone. In addition, we recommend palliative resection of locally unresectable mass with subsequent treatment with high-dose I-131 therapy. Before I-131 therapy, the evaluation of sodium-iodide symporter expression in thyroid carcinoma can predict iodine uptake. Retinoic acid is known to induce redifferentiation, and to enhance I-131 uptake in thyroid carcinoma. Retinoic acid therapy may represent an alternative approach before high-dose I-131 therapy

[en] The annual incidence of primary brain tumors is 7-19 cases per 100,000 people. The unique capacity of visualizing biochemical processes allows PET to determine functional metabolic activities of the brain tumors. Like other malignant tumors, F-18 FDG has been used commonly in the imaging of brain tumors. FDG PET is valuable in grading malignancy, predicting prognosis, monitoring treatment, differentiating tumor recurrence from radiation nucrosis, and detecting primary lesion in metastatric brain tumors. Among amino acids labeled with positron emitters, C-11 methionine is used clinically.Tumor delineation is much better with methionine PET than with FDG PET. Low grade gliomas, in particular, are better evaluated with methionine than with FDG. PET opens another dimension in brain tumor imaging. PET imaging has clearly entered the clinical area with a profound impact on patient care in many indications

[en] Molecular imaging provides a visualization of normal as well as abnormal cellular processes at a molecular or genetic level rather than at an anatomical level. Conventional medical imaging methods utilize the imaging signals produced by nonspecific physico-chemical interaction. However, molecular imaging methods utilize the imaging signals derived from specific cellular or molecular events. Because molecular and genetic changes precede anatomical change in the course of disease development, molecular imaging can detect early events in disease progression. In the near future, through molecular imaging we can understand basic mechanisms of disease, and diagnose earlier and, subsequently, treat earlier intractable disease such as cancer, neuro-degenerative diseases, and immunologic disorders. In beginning period, nuclear medicine started as a molecular imaging, and has had a leading role in the field of molecular imaging. But recently molecular imaging has been rapidly developed. Besides nuclear imaging, molecular imaging methods such as optical imaging, magnetic resonance imaging are emerging. Each imaging modalities have their advantages and weaknesses. The opportunities from molecular imaging look bright. We should try nuclear medicine continues to have a leading role in molecular imaging

[en] Cancer cells are known to show increased rates of glycolysis metabolism. Based on this, PET studies using F-18-fluorodeoxyglucose have been used for the detection of primary and metastatic tumors. To account for this increased glucose uptake, a variety of mechanisms has been proposed. Glucose influx across the cell membrane is mediated by a family of structurally related proteins known as glucose transporters (Gluts). Among 6 isoforms of Gluts, Glut-1 and/or Glut-3 have been reported to show increased expression in various tumors. Increased level of Glut mRNA transcription is supposed to be the basic mechanism of Glut overexpression at the protein level. Some oncogens such as src or ras intensely stimulate Glut-1 by means of increased Glut-1 mRNA levels. Hexokinase activity is another important factor in glucose uptake in cancer cells. Especially hexokinase type II is considered to be involved in glycolysis of cancer cells. Much of the hexokinase of tumor cells is bound to outer membrane of mitochondria by the porin, a hexokinase receptor. Through this interaction, hexokinase may gain preferred access to ATP synthesized via oxidative phosphorylation in the inner mitochondria compartment. Other biologic factors such as tumor blood flow, blood volume, hypoxia, and infiltrating cells in tumor tissue are involved. Relative hypoxia may activate the anaerobic glycolytic pathway. Surrounding macrophages and newly formed granulation tissue in tumor showed greater glucose uptake than did viable cancer cells. To expand the application on FDG PET in oncology, it is important for nuclear medicine physicians to understand the related mechanisms of glucose uptake in cancer tissue

[en] 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 ECG-gated images provided the quantitative 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

[en] I-131 Uptake in thyroid bed in suspicious recurrent thyroid cancer patient was in controversy. The aim of this study was to evaluate the usefulness of F-18 FDG PET in suspicious recurrent thyroid cancer. There were 21 patients (5 men, 16 women; age range, 30-62yr; mean age, 36.3yr) with suspicious recurrent thyroid cancer after total thyroidectomy. An overall clinical evaluation was performed including cytology, thyroglobulin level, sonography, MRI and CT. All patients performed F-18 FDG PET and I-131 whole body scan. In I-131 whole body scan image, all patients have I-131 uptake in thyroid bed. We evaluated FDG uptake in thyroid bed. Among 21 patients, 3 patients were detected FDG uptake in thyroid bed and 8 patients were detected metastatic lesions in neck, mediastinum, lung, bone. Among 21 patients, 15 patients were detected I-131 uptake in thyroid bed without functional metastatic uptake. Among 15 patients without metastatic 131I uptake, 3 patients were detected FDG uptake in thyroid bed. F-18 FDG PET was useful method in diagnosis of recurrent thyroid cancer in thyroid bed. Thus, F-18 FDG PET was inevitable method with I-131 whole body scan in diagnosis of recurrent thyroid cancer

[en] There are several reports about the usefulness of F-18 FDG PET in thyroid cancer. The aim of this study was to evaluate the effectiveness of F-18 FDG PET and I-131 whole body scan in suspicious metastatic thyroid cancer. There were 46 patients (11 men, 35 women; age range, 18-74yr; mean age, 47.3yr) with suspicious metastatic thyroid cancer after total thyroidectomy who performed FDG PET and I-131 scan. The interval of FDG PET and I-131 scan was within 6 months. An overall clinical evaluation was performed including cytology, thyroglobulin level, sonography, MRI and CT. Metastatic regions were divided into four areas: neck, mediastinum, lung and bone. Among 46 patients, the number of patients, metastatic lesions were detected, totaled 36 (78.3%). Twenty-nine patients (63.0%) were detected by FDG PET and 18 patients (39.1%) were detected by I-131 scan. Twenty-one patients were detected in neck by two methods. Nineteen patients (90.5%) were detected by FDG PET and 7 patients (33.3%) were detected by I-131 scan. Eighteen patients were detected in mediastinum by two methods. Ten patients (55.5%) were detected by FDG PET and 10 patients (55.5%) were detected by I-131 scan. Ten patients were detected in lung by two methods. Nine patients (90.0%) were detected by FDG PET and 3 patients (30.0%) were detected by I-131 scan. Three patients were detected in bone by two methods. Three patients (100%) were detected by FDG PET and 0 patients (0%) were detected by I-131 scan. These data indicate that for detecting metastatic lesions, F-18 FDG PET and I-131 whole body scan may provide complementary information. Thus, the combination of FDG PET and I-131 scan is the method of choice for detecting suspicious metastatic thyroid cancer after total thyroidectomy

[en] A simple imaging procedure has been devised for patients with peritoneo-venous shunts when ascites reaccumulates and a decision must be made on whether or not to revise the shunt. We recently experienced a patient with reaccumulated ascites in whom obstruction of peritoneo-venous shunt was suspected. 5 mCi of ^99mTc-phytate was injected into the peritoneal cavity and imaging of the abdomen was performed 1-30 minutes later. With a proper functioning shunt, radioactivity in the liver and spleen were easily identifiable in this case. If the shunt is obstructed, tracer activity will remain in the peritoneal cavity and thus can not be identifiable m the liver or spleen. Conclusively, radionuclide methods might be very useful for evaluation of peritoneo-venous shunt patency.

[en] A simple imaging procedure has been devised for patients with peritoneo-venous shunts when ascites reaccumulates and a decision must be made on whether or not to revise the shunt. We recently experienced a patient with reaccumulated ascites in whom obstruction of peritoneo-venous shunt was suspected. 5mCi of ⁹⁹mTc-phytate was injected into the peritoneal cavity and imaging of the abdomen was performed 1-30 minutes later. With a proper functioning shunt, radioactivity in the liver and spleen were easily identifiable in this case. If the shunt is obstructed, tracer activity will remain in the peritoneal cavity and thus can not be identifiable in the liver or spleen. Conclusively, radionuclide methods might be very useful for evaluation of peritoneo-venous shunt patency. (Author)

[en] Since the introduction of nuclear medicine in 1959, Korea accomplished a brilliant development in terms of both clinical practice and research activities, which was mainly due to the dedication of nuclear medicine specialists, consisting of physicians, technicians, and scientists, and strong support from the Korean Government. Now, Korea has 150 medical institutes, performing approximately 561,000 nuclear imaging procedures and 11.6 million in vitro studies in 2008, and ranked fourth in the number of presentations at the Annual Meeting of the Society of Nuclear Medicine (SNM) in 2008. The successful progress in this field has allowed Korea to focus on the international promotion of nuclear medicine, especially in the developing and underdeveloped countries. In consequence, the Asian Regional Cooperative Council for Nuclear Medicine (ARCCNM) was established in 2001, and Seoul hosted the 9th Congress of the World Federation of Nuclear Medicine and Biology (WFNMB) in 2006. In the future, Korea will strive to sustain its rate of advancement in the field and make every effort to share its progress and promote the exchange of scientific information at the international level.