• Nuclear Medicine and Molecular Imaging
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• v.42 no.sup1
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• pp.46-51
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• 2008

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal neoplasm of the gastrointestinal tract, and can be distinguished from the smooth muscle or neural tumors in approximately 95% of patients by expression of the KIT receptor tyrosine kinase (CD117). GISTs are known to have high malignant potential and none can be labeled definitely as benign. However, GISTs are unresponsive to standard sarcoma chemotherapy, and only complete surgical resection provides chance for cure. Although the imaging modality of choice is enhanced CT scan in patients with GIST, FDG PET can reflect the malignant potential of GIST. Clinical management of patients with GISTs has dramatically changed with the introduction of novel therapeutics, such as imatinib mesylate (Glivec). This has created a need to re-evaluate the existing criteria used to assess treatment response. FDG PET as functional imaging modality proved to be significantly more accurate than CT alone when assessing GIST response to imatinib. And, FDG PET and PET ICT have been found to be highly sensitive in detecting early response, and to be useful in predicting long-term response to imatinib in patients with recurrent or metastatic GISTs.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.23
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• pp.10057-10059
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• 2015

Positron emission tomography (PET) as the functional component of current hybrid imaging (like PET/CT or PET/MRI) seems to dominate the horizon of medical imaging in coming decades. $^{18}$Flourodeoxyglucose ($^{18}FDG$) is the most commonly used probe in oncology and also in cardiology and neurology around the globe. However, the major capital cost and exorbitant running expenditure of low to medium energy cyclotrons (about 20 MeV) and radiochemistry units are the seminal reasons of low number of cyclotrons but mushroom growth pattern of PET scanners. This fact and longer half-life of $^{18}F$ (110 minutes) have paved the path of a centralized model in which $^{18}FDG$ is produced by commercial PET radiopharmacies and the finished product (multi-dose vial with tungsten shielding) is dispensed to customers having only PET scanners. This indeed reduced the cost but has limitations of dependence upon timely arrival of daily shipments as delay caused by any reason results in cancellation or rescheduling of the PET procedures. In recent years, industry and academia have taken a step forward by producing low energy, table top cyclotrons with compact and automated radiochemistry units (Lab-on-Chip). This decentralized strategy enables the users to produce on-demand doses of PET probe themselves at reasonably low cost using an automated and user-friendly technology. This technological development would indeed provide a real impetus to the availability of complete set up of PET based molecular imaging at an affordable cost to the developing countries.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.sup1
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• pp.101-109
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• 2008

Cervix cancer is one of common gynecological cancers in the world, and staged with FIGO or TNM system. However, these clinical staging systems lack information about lymph node or distant metastases, thus imaging modalities are considered to make an appropriate therapeutic plan and enhance overall survival rate. In this context, FDG PET is recommended to pre-treatment stating and prognosis prediction, for it could noninvasively evaluate the status of lymph nodes, especially abdominal paraaortic nodes which are closely related with prognosis. Moreover, the degree of FDG uptake is correlated with prognosis. Although there is no consistent method for surveillance of cervix cancer, FDG PET seems a very important tool in detecting tumor recurrence because it is much more advantageous than conventional imaging modalities such as MRI for discerning recurrent tumor from fibrosis caused by radiation or surgery. Furthermore, FDG PET could be used to evaluate treatment response. On the other hand, recently introduced PET/CT is expected to play an ancillary role to FIGO staging by adding anatomical information, and enhance diagnostic performance of PET by decreasing false positive findings.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.1
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• pp.62-66
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• 2015

Purpose Various database comparison methods(DCM) are used for analyzing functional neuro-imaging. It is possible to statistically evaluate decreased or increased metabolism of abnormal patient's brain by comparing with asymptomatic controls in DCM. And results of DCM are additionally used for easily explaining defect region. The aim of this study was to evaluate usefulness of statistical parametric mapping(SPM) and scenium. Materials and Methods Data of 15 patients($62.02{\pm}15.03year$) underwent $^{18}F-FDG$ brain PET/CT were collected and analyzed. Biograph TruePoint 40 with TrueV, (Siemens) was used as a PET/CT scanner. Scenium(version 4.0) in Syngo.via(version VA30A) and SPM99 were applied for statistical evaluation. Consistency between PET reading and result of DCM were evaluated by 5 nuclear medicine physicians through a questionnaire survey. SUV and SD changes were evaluated by changing iteration, gaussian filter and matrix size in scenium. And average required time for generating result of SPM99 and scenium was compared by 3 medical technologists. Results Consistency from the result of SPM99 and scenium showed 84% and 92.4% compare to PET reading. When iteration 4, FWHM 8 and matrix size 168, SUV and SD were decreased by 0.59%, 8.73%, 4.69%, 20.38% and 0.88%, 8.25% respectively compare to routine parameter(iteration 8, FWHM 2 and matrix size 336) of scenium. Average required time of SPM99 and Scenium took 282 seconds and 116 seconds to generate result. Conclusion Results of SPM99 and Scenium showed high consistency compare to PET reading. Various parameters can be controled by user when using SPM. However, normal database needs to be acquired. And it takes significant amount of time and effort for the first set up. On the other hand, Scenium provides normal database even though modifiable parameters are limited. Therefore, more informations could be provided for brain PET/CT if properly understanding and selecting each DCM.

• Journal of the Korean Society of Radiology
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• v.10 no.4
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• pp.255-261
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• 2016

In this study, among various factors having influence on SUV, we intended to compare and analyze the change of SUV using CT(4 type) and MRI(3 type) contrast agents which are commercialized now. We used Discovery 690 PET/CT(GE) and NEMA NU2 - 1994 PET phantom as experimental equipment. We have conducted a study as follows; first, we filled distilled water to phantom about two-thirds and injected radioisotope(18F-FDG 37 MBq), contrast agent. Second, we mixed CT contrast agent with distilled water and MRI contrast agent with that water separately. And then, we stirred the fluid and filled distilled water fully not to make air bubble. In emission scan, we had 15minutes scanning time after 40 minutes mixing contrast agent with distilled water. In transmission scan, we used CT scanning and its measurement conditions were tube voltage 120 kVp, tube current 40 mA, rotation time 0.5 sec, slice thickness 3.27 mm, DFOV 30 cm. Analyzing results, we set up some ROIs in 10th, 15th, 20th, 25th, 30th slice and measured SUVmean, SUVmax. Consequently, all images mixed 3 types of MRI contrast agent with distilled water have high SUVmean as compared with pure FDG image but there was no statistical significance. In SUVmax, they have high score and there was statistical significance. And other 4 images mixed 4 types of CT contrast agent with distilled water have significance in both SUVmean and SUVmax. Attenuation correction in PET/CT has been executed through various methods to make high quality image. But we figured out that using CT and MRI contrast agents before PET/CT scanning could make distortion of image and decrease diagnostic value. In that reason, we have to sort out the priority of examination in hospital not to disturb other examination's results. Through this process, we will be able to give superior medical service to our customers.

• Korean Journal of Radiology
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• v.22 no.5
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• pp.714-724
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• 2021

Objective: To evaluate the value of ¹⁸F-fluorodeoxyglucose PET/MRI added to contrast-enhanced CT (CECT) in initial staging, assessment of resectability, and postoperative follow-up of biliary tract cancer. Materials and Methods: This retrospective study included 100 patients (initial workup [n = 65] and postoperative follow-up [n = 35]) who had undergone PET/MRI and CECT for bile duct or gallbladder lesions between January 2013 and March 2020. Two radiologists independently reviewed the CECT imaging set and CECT plus PET/MRI set to determine the likelihood of malignancy, local and overall resectability, and distant metastasis in the initial workup group, and local recurrence and distant metastasis in the follow-up group. Diagnostic performances of the two imaging sets were compared using clinical-surgical-pathologic findings as standards of reference. Results: The diagnostic performance of CECT significantly improved after the addition of PET/MRI for liver metastasis (area under the receiver operating characteristic curve [A_z]: 0.77 vs. 0.91 [p = 0.027] for reviewer 1; 0.76 vs. 0.92 [p = 0.021] for reviewer 2), lymph node metastasis (0.73 vs. 0.92 [p = 0.004]; 0.81 vs. 0.92 [p = 0.023]), and overall resectability (0.79 vs. 0.92 [p = 0.007]; 0.82 vs. 0.94 [p = 0.021]) in the initial workup group. In the follow-up group, the diagnostic performance of CECT plus PET/MRI was significantly higher than that of CECT imaging for local recurrence (0.81 vs. 1.00 [p = 0.029]; 0.82 vs. 0.94 [p = 0.045]). Conclusion: PET/MRI may add value to CECT in patients with biliary tract cancer both in the initial workup for staging and determination of overall resectability and in follow-up for local recurrence.

• Radiation Oncology Journal
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• v.33 no.3
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• pp.179-187
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• 2015

Purpose: The purpose of this study was to investigate the predictable value of pretreatment $^{18}F$-fluorodeoxyglucose positron emission tomography-computed tomography ($^{18}F$-FDG PET-CT) in radiotherapy (RT) for patients with hepatocellular carcinoma (HCC) or portal vein tumor thrombosis (PVTT). Materials and Methods: We conducted a retrospective analysis of 36 stage I-IV HCC patients treated with RT. $^{18}F$-FDG PET-CT was performed before RT. Treatment target was determined HCC or PVTT lesions by treatment aim. They were irradiated at a median prescription dose of 50 Gy. The response was evaluated within 3 months after completion of RT using the Response Evaluation Criteria in Solid Tumors (RECIST). Response rate, overall survival (OS), and the pattern of failure (POF) were analyzed. Results: The response rate was 61.1%. The statistically significant prognostic factor affecting response in RT field was maximal standardized uptake value (maxSUV) only. The high SUV group (maxSUV ${\geq}5.1$) showed the better radiologic response than the low SUV group (maxSUV < 5.1). The median OS were 996.0 days in definitive group and 144.0 days in palliative group. Factors affecting OS were the %reduction of alpha-fetoprotein (AFP) level in the definitive group and Child-Pugh class in the palliative group. To predict the POF, maxSUV based on the cutoff value of 5.1 was the only significant factor in distant metastasis group. Conclusion: The results of this study suggest that the maxSUV of $^{18}F$-FDG PET-CT may be a prognostic factor for treatment outcome and the POF after RT. A %reduction of AFP level and Child-Pugh class could be used to predict OS in HCC.

• Tuberculosis and Respiratory Diseases
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• v.64 no.2
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• pp.133-137
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• 2008

Pulmonary paragonimiasis continues to be a diagnostically challenging parasitic disease, despite a drastically decreased prevalence in South Korea during the past decade. Pulmonary paragonimiasis is characterized by fever, chest pain, and chronic cough with hemoptysis. Numerous radiographic and computed tomographic findings including the presence of pneumothorax, pleural effusion, and parenchymal lesions such as nodular or infiltrative opacities have been reported. The clinical and radiological manifestations of paragonimiasis can resemble those of lung cancer, tuberculosis or a metastatic malignancy. Furthermore, this disease can mimic lung cancer as seen on $^{18}F$-fluorodeoxyglucose positron emission tomography (FDG-PET). We report a case of pulmonary paragonimiasis in a 48-year old man that presented with a solitary pulmonary nodule and was suspected as a lung cancer based on FDG-PET imaging.

• The Korean Journal of Nuclear Medicine Technology
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• v.27 no.1
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• pp.62-65
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• 2023

Purpose The purpose of this study is to determine whether the glucose loading method (GLM) is useful in the differentiation of cerebral gliomas by comparing it with fasting images. Materials and Methods The patients were 70 people diagnosed with cerebral gliomas, and the equipment was Discovery 710 (GE Healthcare, MI, USA). All patients fasted for more than 6 hours, and fasting images and GLM were performed under the same imaging conditions, and the examination interval was 1 to 14 days. GLM administered 250 ㎖ of 10% glucose solution prior to radiopharmaceutical injection. SUVmax of cerebral glioma and SUVmean of cerebral cortex were measured and then compared and analyzed by tumor-to-normal brain cortex ratio (TNR). Statistical analysis confirmed the difference between the two images with an independent-sample t-test. Results The averages of GLM and fasting TNR were 1.26 and 1.09, respectively, which were 15.6% higher in GLM. In low-grade, the difference in TNR was insignificant at 4%, but in high-grade, 23%, GLM was high. There was a statistically significant difference between the two images (P=0.008), but there was no statistically significant difference in TNR in the low grade (P=0.473), and there was a very significant difference in the high grade (P=0.005). Conclusion GLM increased TNR for cerebral gliomas. In particular, it was found that the TNR increased more in the high grade. Therefore, GLM is considered to be useful for the differentiation of high-grade gliomas.

• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.935-942
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• 2021

Involuntary movement of internal organs by respiration is a factor that greatly affects the results of radiotherapy and diagnosis. In this study, a moving phantom was fabricated to simulate the movement of an organ or a tumor according to respiration, and ¹⁸F-FDG PET/CT scan images were acquired under various respiratory simulating conditions to analyze the movement range of the tumor movement by respiration, the level of artifacts according to the size of the tumor and the maximum standardized uptake value (SUVmax). Based on Windows CE 6.0 as the operating system, using electric actuator, electric actuator positioning driver, and programmable logic controller (PLC), the position and speed control module was operated normally at a moving distance of 0-5 cm and 10, 15, and 20 reciprocations. For sphere diameters of 10, 13, 17, 22, 28, and 37 mm at a delay time of 100 minutes, 80.4%, 99.5%, 107.9%, 113.1%, 128.0%, and 124.8%, respectively were measured. When the moving distance was the same, the difference according to the respiratory rate was insignificant. When the number of breaths is 20 and the moving distance is 1 cm, 2 cm, 3 cm, and 5 cm, as the moving distance increased at the sphere diameters of 10, 13, 17, 22, 28, and 37 mm, the ability to distinguish images from smaller spheres deteriorated. When the moving distance is 5 cm compared to the still image, the maximum values of the standard intake coefficient were 18.0%, 23.7%, 29.3%, 38.4%, 49.0%, and 67.4% for sphere diameters of 10, 13, 17, 22, 28, and 37 mm, respectively.