• Journal of the Korean Society of Safety
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• v.24 no.6
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• pp.157-162
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• 2009

Radioactive medicines are used a lot owing to the increase of a PET-CT examination using glucose metabolism useful for the early diagnosis of diseases. Therefore, the spatial dose that is generated from patients and their surroundings causes the patients' guardians and health professional to be exposed to radiation. However, they get unnecessarily exposed to radiation because medical institutions lack in space for isolation and recognition of the examination. This research intended to examine the spatial dose rates by measuring the dose emitted from the patient for 48 hours to whom F-18 FDG was administered. The spatial dose rates that were measured 100cm away from the patient's body after F-18 FDG was injected were $65.88{\mu}$Sv/hr at 60-minute point, $45.13{\mu}$Sv/hr at 90-minute point, $9.88{\mu}$Sv/hr at 6-hour point, and $1.24{\mu}$Sv/hr at 12-hour point. When the dose that the guardian and health professional got was converted into the annual(240-day working) accumulative dose, it was examined that the guardian received 81.56 mSv/yr and health professional received 49.36mSv/yr. In addition, the result has revealed that the dose that the patient received from one time of PET-CT examination was 3.75mSv/yr, which is 1.5 times more when compared with the annual natural radiation exposure dose.

• Korean Journal of Head & Neck Oncology
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• v.19 no.1
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• pp.58-62
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• 2003

Purpose: To evaluate the efficacy of positron emission tomography with 2-[F-18] fluoro-2-deoxy-D-glucose in discrimination of response in the nasopharyngeal carcinoma patients who treated with radiotherapy. Methods and Materials: Twenty-four patients who underwent FDG-PET scan before and after radiotherapy for no disseminated head and neck carcinoma at the Asan Medical Center between August 2001 and September 2002 were evaluate by prospective analysis. First FDG-PET scan performed before radiotherapy within 1 month, and second FDG-PET scan performed 1 month after radiotherapy. FDG-PET images were analyzed by standard uptake value (SUV). Follow-up period was more than 6 months. Results: The pretreatment SUV was 3.4-14.0 (median: 6.0) and posttreatment SUV was ground level-7.7 (median: 2.0). The overall sensitivity and specicity of FDG-PET to evaluate residual tumors in the nasopharyngeal carcinoma patients were 94% and 94%. Conclusion: FDG-PET is effective in evaluation of radiation response in the nasopharyngeal carcinoma. We think that the timing of one month after finished radiotherapy FDG-PET scan was not too fast to evaluation of radiation response.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.5
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• pp.421-428
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• 2009

Purpose: We have evaluated characteristics of adrenal masses incidentally observed in nonenhanced F-18 FDG PET/CT of the oncologic patients and the diagnostic ability of F-18 FDG PET/CT to differentiate malignant from benign adrenal masses. Materials and Methods: Between Mar 2005 and Aug 2008, 75 oncologic patients (46 men, 29 women; mean age, $60.8{\pm}10.2$ years; range, 35-87 years) with 89 adrenal masses incidentally found in PET/CT were enrolled in this study. For quantitative analysis, size (cm), Hounsfield unit (HU), maximum standardized uptake value (SUVmax), SUVratio of all 89 adrenal masses were measured. SUVmax of the adrenal mass divided by SUVliver, which is SUVmax of the segment 8, was defined as SUVratio. The final diagnosis of adrenal masses was based on pathologic confirmation, radiologic evaluation (HU<0 : benign), and clinical decision. Results: Size, HU, SUVmax, and SUVratio were all significantly different between benign and malignant adrenal masses.(P < 0.05) And, SUVratio was the most accurate parameter. A cut-off value of 1.0 for SUVratio provided 90.9% sensitivity and 75.6% specificity. In small adrenal masses (1.5 cm or less), only SUVratio had statistically significant difference between benign and malignant adrenal masses. Similarly a cut-off value of 1.0 for SUVratio provided 80.0% sensitivity and 86.4% specificity. Conclusion: F-18 FDG PET/CT can offer more accurate information with quantitative analysis in differentiating malignant from benign adrenal masses incidentally observed in oncologic patients, compared to nonenhanced CT.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.5
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• pp.402-410
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• 2009

Purpose: The aim of this study was to determine the incidence and malignant rate of incidental asymmetric palatine tonsillar uptake (ATU) on $^{18}F$-FDG PET/CT in various clinical indications and to evaluate the clinical and PET/CT findings suggesting malignancy. Materials and Methods: We retrospectively reviewed a total of 2,901 patients ($58.4{\pm}12.3$ yrs, range 20~88 yrs, M:F = 1,841:1,060) who underwent $^{18}F$-FDG PET/CT during an 1-year period with various indications except primary tonsillar cancer and lymphoma evaluation. On $^{18}F$-FDG PET/CT, metabolic abnormality of the palatine tonsil and cervical lymph node were visually assessed. ATU was defined as increased palatine tonsillar uptake with diffuse, focal, or irregular pattern compared to contralateral side. The incidence and malignant ratio of ATU were evaluated according to clinical and PET/CT findings. Results: Of 2,901 cases, 290(10,0%) showed ATU. The incidence of ATU showed seasonal variation and was high in the winter (12.1%). Of 209 cases with ATU confirmed pathologically and/or clinically, five (2.4%) were malignant lesions. ATU with irregular uptake pattern (2/2) and in cases referred for cervical lymph node metastasis of unknown origin (3/5) were frequently associated with malignant lesion (p<0.05). Conclusion: ATU was not infrequently observed on $^{18}F$-FDG PET/CT, and the malignant risk of ATU was low. However, ATU with cervical lymph node metastasis or with irregular pattern on PET/CT would be further evaluated by the histopathologic examination.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.4
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• pp.317-322
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• 2009

Purpose: $^{18}$F-flurodeoxyglucose (FDG) uptake on positron emission tomography (PET) scan has been found to reflect tumor aggressiveness and prognosis in various types of cancer. However, pattern of FDG uptake in biliary malignancies and its clinical significance have not been studied well. The purpose of this study was to assess the additional value of $^{18}$F-FDG PET in differential diagnosis and prognosis of cholangiocarcinoma (CC) according to the tumor location and tumor morphology. Materials and Methods: From April 2005 to May 2008, eighty two patients (M:F = 55:27, age 66.2$\pm$9.6 yrs) with CC underwent $^{18}$F-FDG PET. For semiquantitative analysis, the maximum standardized uptake value (SUV$_{max}$) was obtained from the primary tumor. The difference of SUV$_{max}$ according to the tumor location and tumor growth pattern, such as scirrhous type, nodular type, polypoid type were compared. Results: Overall sensitivity of PET scan was 81.7% in CC. SUV$_{max}$ on PET scan in intrahepatic CC was significantly higher compared to extrahepatic CC. In extrahepatic CC, polypoid type showed significantly higher SUV$_{max}$ compared to scirrhous type. Conclusion: $^{18}$F-FDG PET may have a significant impact on clinical decision-making and on the management of intrahepatic cholangiocarcinoma. And it is related to the shape of the tumor and the sensitivity of detection is higher in the mass-forming type than in the scirrhous type.

• Journal of the Korean Society of Radiology
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• v.82 no.4
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• pp.903-913
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• 2021

Purpose To identify the imaging features indicative of sarcoid-like reactions in patients with intrathoracic lymphadenopathy after complete remission of malignancies. Materials and Methods This study enrolled five patients with histopathologically confirmed sarcoid-like reactions that developed after cancer remission. The clinical features and findings of CT and ¹⁸F-fluorodeoxyglucose (FDG) PET/CT were assessed. Results The underlying malignancies included breast, nasopharyngeal, colon, and endometrial cancer and lymphoma. The time intervals between complete remission of malignancy and the diagnosis of sarcoid-like reaction ranged from 6 to 78 months. CT findings of sarcoid-like reaction included bilateral hilar and mediastinal lymphadenopathies (n = 5), pulmonary nodules (1-15 mm) with peribronchovascular, fissural, or subpleural distribution, and interlobular interstitial thickening in the lungs (n = 4). ¹⁸F-FDG PET/CT revealed hypermetabolic uptake in the mediastinal and hilar lymph nodes and both lungs in the absence of extrathoracic uptake (n = 3). The sarcoid-like reactions resolved in all patients after corticosteroid treatment. Conclusion In patients with complete remission of malignancies, newly developed bilateral hilar and mediastinal lymphadenopathies with or without pulmonary nodules of perilymphatic distribution, in the absence of recurrence at the primary tumor site and extrathoracic metastasis, may suggest a sarcoid-like reaction. Such cases warrant histologic evaluation of the lymph nodes to prevent unnecessary systemic chemotherapy.

• The Korean Journal of Nuclear Medicine
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• v.37 no.1
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• pp.24-33
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• 2003

Finding epileptogenic zone is the most important step for the successful epilepsy surgery. F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and single photon emission computed tomography (SPECT) can be used in the localization of epileptogenic foci. In medial temporal lobe epilepsy, the diagnostic sensitivity of FDG-PET and ictal SPECT is excellent. However, detection of hippocampal sclerosis by MRI is so certain that use of FDG-PET and ictal SPECT in medial temporal lobe epilepsy is limited for some occasions. In neocortical epilepsy, the sensitivities of FDG-PET or ictal SPECT are fair. However, FDG-PET and ictal SPECT can have a crucial role in the localization of epileptogenic foci for non-lesional neocortical epilepsy. Interpretation of FDG-PET has been recently advanced by voxel-based analysis and automatic volume of interest analysis based on a population template. Both analytical methods can aid the objective diagnosis of epileptogenic foci. Ictal SPECT was analyzed using subtraction methods and voxel-based analysis. Rapidity of injection of tracers, ictal EEG findings during injection of tracer, and repeated ictal SPECT were important technical issues of ictal SPECT. SPECT can also be used in the evaluation of validity of Wada test.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.sup1
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• pp.39-45
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• 2008

PET or PET/CT detects only less than 50% of early gastric cancer and 62-98% of advanced gastric cancer. Therefore, mass screening programs are recommended for all adults over the age of 40 for early detection and early treatment of gastric cancer through endoscopy or various radiological tests. The most important step after diagnosis of gastric cancer is accurate staging, which mainly evaluates tumor resectability to avoid unnecessary surgery. Important factors that affect tumor resectability are whether the tumor can be separated from adjacent organs or important blood vessels, the extent of lymph node metastasis, presence of peritoneal metastasis, or distant organ metastasis. To evaluate the extent of local tumor invasion, anatomical imaging that has superior spatial resolution is essential. There are a few studies on prognostic significance of FDG uptake with inconsistent results between them. In spite of lower sensitivity for lymph node staging, the specificity of CT and PET are very high, and the specificity for PET tends to be higher than that for CT. Limited data published so far show that PET seems less useful in the detection of lung and bone metastasis. In the evaluation of pleural or peritoneal metastasis, PET seems very specific but insensitive as well. When FOG uptake of primary tumor is low, distant metastasis also tends to show low FDG uptake reducing its detection on PET. There are only a few data available in the evaluation of recurrence detection and treatment response using FDG PET or PET/CT.

• The Korean Journal of Nuclear Medicine
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• v.39 no.6
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• pp.456-463
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• 2005

Purpose: we often find variable degrees of FDG uptake and patterns in stomach, which can make difficult to distinguish physiologic uptake from pathologic uptake on FDG PET. The purpose of this study was to find out the significant findings of stomach on FDG PET. Materials and Methods: Thirty-eight patients who underwent both FDG PET and endoscopy within one week from Jun. 2003, to Aug. 2004 were included in this study. We reviewed 38 patients (18 for medical check up, 15 for work up of other malignancies, and 5 for the evaluation of stomach lesion). Their mean age was 56 years old (range:$32{\sim}79$), men and women were 28 and 10, respectively. Two nuclear physicians evaluated five parameters on FDG PET findings of stomach with a consensus: 1) visual grades 2) maximum SUV (max.SUV) 3) focal 4) diffuse and S) asymmetric patterns. We correlated the lesions of FDG PET findings of stomach with those of endoscopy. We considered more than equivocal findings on FDG PET as positive. Results: The six of 38 patients were proven as malignant lesions by endoscopic biopsy and others were inflammatory lesions (ulcer in 3, chronic atrophic gastritis in 12, uncommon forms of gastritis in 5), non-inflammatory lesions (n=3), and normal stomach (n=9). By the visual analysis, malignant lesions had higher FDG uptake than the others. The max.SUV of malignant lesions was $7.95{\pm}4.83$ which was significantly higher than the other benign lesions ($2.9{\pm}0.69$ in ulcer, $3.08{\pm}1.2$ in chronic atrophic gastritis, $3.2{\pm}1.49$ in uncommon forms of gastritis (p=0.044)). In the appearance of stomach on FDG PET, malignant lesions were shown focal (5 of 6) and benign inflammatory lesions were shown diffuse (9 of 20) and asymmetric (14 of 20). Benign lesions and normal stomach were shown variable degrees of uptake and patterns. Some cases of benign inflammatory lesions such as ulcer and gastritis were shown focal and mimicked cancerous lesion (4 of 15). Conclusion: Gastric malignant lesions had higher FDG uptake and focal pattern. However, benign inflammatory lesions had moderate degrees of uptake and diffuse and asymmetric patterns rather than focal. It is difficult to differentiate between benign lesions including normal.

• The Korean Journal of Nuclear Medicine
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• v.39 no.1
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• pp.15-20
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• 2005

Purpose: Physiologic intestinal FDG uptake is frequently observed in asymptomatic individuals for cancer screening FDG PET Colonic FDG accumulation is a well-known confusing findings that interfere true cancer detection or cause false positive. The aim of this study was to evaluate the pattern and intensity of colonic uptake in whole body FDG PET in asymptomatic healthy adults and to correlate them with colonoscopic findings. Materials and Methods: We reviewed retrospectively 64 subjects (age: 27-87, M:F=31:33) who underwent both FDG PET and colonoscopy for cancer screening. FDG uptake patterns were classified as focal, segmental and diffuse. Maximum SUV were measured. The PET results were compared with colonoscopic and histologic findings. Results: In 13 patients FDG bowel uptake was interpreted as focal, in 17 patients as segmental and in 34 patients as diffuse uptake. Six adenomas (17.6%, average diameter=5.0 mm) were found in diffuse pattern, 7 adenomas (41.1%, 5.6 mm) in segmental and 4 adenomas and 1 adenocarcinoma (38.5%, 16.4 mm) in focal uptake pattern. In patients with focal uptake, four were non-adenomatous pathologic lesions (30.8%, 2 intestinal tuberculosis, 2 mucosal ulcer). There is no difference of mean SUV between patients with adenoma and with negative colonoscopic results in each group of intestinal FDG pattern (Diffuse: $1.7{\pm}0.1\;vs.\;1.9{\pm}0.5$, Segmental: $4.8{\pm}3.6\;vs.\;4.2{\pm}1.2$, Focal: $6.5{\pm}4.7\;vs.\;3.5{\pm}1.3$). large adenomas (>1 cm) can be detected more in the focal uptake pattern (4 out of 5) rather than in segmental (1 out of 7) or diffuse uptake (none) and had higher SUV ($6.3{\pm}4.8$) than small adenomas ($3.5{\pm}3.0$) (statistically insignificant). Conclusion: focal FDG uptake is associated more often with large adenoma and other pathologic findings in colonoscopy. Segmental uptake cannot discriminate presence of adenoma from negative results, while diffuse pattern may have more chance to be normal.