• Journal of Gastric Cancer
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• v.17 no.4
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• pp.384-393
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• 2017

Purpose: The tumor microenvironment is known to be associated with the metabolic activity of cancer cells and local immune reactions. We hypothesized that glucose metabolism measured by 2-deoxy-2-($^{18}F$)fluoro-D-glucose ($^{18}F-FDG$) positron emission tomography (PET)-computed tomography (CT) ($^{18}F-FDG$ PET-CT) would be associated with local immune responses evaluated according to the presence of tumor infiltrating lymphocytes (TILs). Materials and Methods: We retrospectively reviewed 56 patients who underwent $^{18}F-FDG$ PET-CT prior to gastrectomy. In resected tumor specimens, TIL subsets, including cluster of differentiation (CD) 3, CD4, CD8, Forkhead box P3 (Foxp3), and granzyme B, were subjected to immunohistochemical analysis. The prognostic nutritional index (PNI) was calculated as: ($10{\times}serum$ albumin value)+($0.005{\times}peripheral$ lymphocyte counts). Additionally, the maximum standard uptake value ($SUV_{max}$) was calculated to evaluate the metabolic activity of cancer cells. Results: The $SUV_{max}$ was positively correlated with larger tumor size (R=0.293; P=0.029) and negatively correlated with PNI (R=-0.407; P=0.002). A higher $SUV_{max}$ showed a marginal association with higher CD3 (+) T lymphocyte counts (R=0.227; P=0.092) and a significant association with higher Foxp3 (+) T lymphocyte counts (R=0.431; P=0.009). No other clinicopathological characteristics were associated with $SUV_{max}$ or TILs. Survival analysis, however, indicated that neither $SUV_{max}$ nor Foxp3 held prognostic significance. Conclusions: FDG uptake on PET-CT could be associated with TILs, especially regulatory T cells, in gastric cancer. This finding may suggest that PET-CT could be of use as a non-invasive tool for monitoring the tumor microenvironment in patients with gastric cancer.

• 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.

• The Korean Journal of Nuclear Medicine
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• v.35 no.3
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• pp.198-204
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• 2001

Cyclic Vomiting Syndrome (CVS) is characterized by recurrent, periodic, self-limiting vomiting. However, its pathogenesis is not yet established. We investigated the changes of the cerebral glucose metabolism using F-18 FDG during the vomiting attack and symptom free period in two children with CVS. FDG PET study showed the markedly increased metabolism in both temporal lobes and also in the medulla and cerebellum during the vomiting period. Also, FDG PET showed the decreased metabolism un the parieto-occipital and occipital areas during the vomiting period. The area with decreased metabolism seemed to be related with the region showing abnormalities in EEG and perfusion SPECT studies. We expect that what we observed would be a helpful finding in clarifying the pathogenesis of the CVS.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.1
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• pp.39-43
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• 2008

Purpose: We evaluated whether it was necessary to perform whole body acquisition of $^{18}F$-FDG PET/CT including whole skull and lower extremity (LE) distal to mid-thigh (MT) in patients with multiple myeloma (MM). Materials and Methods: Thirty patients underwent 45 whole body $^{18}F$-FDG PET/CT scans including skull and LE distal to MT. PET scans were divided by 2 subgroups according to the presence of abnormal focal $^{18}F$-FDG uptake in skull or LE distal to MT. Clinical characteristics including age, sex, and stages were compared between the 2 subgroups. Results: Of total 45 whole body PET/CT scans, focally increased abnormal FDG uptake in the skull or LE distal to MT suggesting myeloma involvement was found in 22 scans (48.9%) of 14 patients (46.7%). Skull lesions were more frequently observed than LE lesions distal to MT on PET (86.4% vs. 40.9%, p<0.005). There were no significant differences in age, sex, initial Durie/Salmon stage, and tumor burden at the time of PET scan suggested by serum hemoglobin level, serum calcium level, serum and urine paraprotein level, and serum creatinine level between the two subgroups. The presence of the skull or LE distal MT lesions on PET did not affect on the Durie/Salmon plus stage except only 1 case (1/22, 4.5%, p>0.05). Conclusion: Abnormal lesions in the skull or LE distal to MT on $^{18}F$-FDG PET/CT did not affect significantly on the tumor burden and Durie/Salmon plus stage of MM. Therefore, torso PET acquisition including head may be sufficient for evaluating patients with MM.

• 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.

• The Korean Journal of Nuclear Medicine
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• v.36 no.1
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• pp.19-27
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• 2002

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 necrosis, 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.

• The Korean Journal of Nuclear Medicine
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• v.34 no.4
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• pp.276-284
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• 2000

Purpose: We investigated the operative outcome after bypass surgery in patients selected using viability criteria on F-18 FDG PET. Materials and Methods: Rest-24hr delay redistribution imaging of Tl-201 SPECT and F-18 FDG PET were performed in 11 patients. Seven of these 11 patients (6 men, 1 woman) were evaluated to have viable myocardium by F-18 FDG PET. Changes in symptoms and left ventricular ejection fraction (LVEF) after operation were evaluated. Results: In seven of 11 patients, a significant amount of viable myocardium was found on F-18 FDG PET and Tl-201 SPECT. Severity of both chest pain and dyspnea improved markedly in all patients. Mean LVEF improved from 22% to 32%. Conclusion: F-18 FDG PET could be used to select the patients who will benefit from coronary artery bypass surgery.

• The Korean Journal of Nuclear Medicine
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• v.36 no.2
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• pp.143-145
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• 2002

A 49-year-old male patient with a carcinoma of the right pyriform sinus had a whole-body bone scan and gamma camera based F-18 FDG-PET for staging. Tc-99m MDP bone scan depicted diffuse increased uptake in the left femur due to chronic osteomyelitis but no skeletal metastasis. F-18-FDG-PET revealed increased focal bone uptake and uptake in the draining sinus due to chronic osteomyelitis in addition to visualization of the right pyriform sinus carcinoma and right neck nodal uptake. Fluorine-18 fluorodeoxyglucose-positron emission tomography is significantly more accurate than the bone scan in pinpointing chronic osteomyelitis focus and draining soft tissue infection.

• Dementia and Neurocognitive Disorders
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• v.17 no.3
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• pp.90-99
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• 2018

Background and Purpose: To explore anatomic substrate of specific wandering patterns in patients with Alzheimer's disease (AD) by performing positron emission tomography with $^{18}F$ fluorodeoxyglucose positron emission tomography (FDG PET). Methods: Drug-naïve AD patients with wandering (n=80) and without wandering (n=262) were recruited. First, the specific pattern of wandering type was operationally classified according to specific wandering score and clinical assessment. Second, brain FDG PET was performed and fluorodeoxyglucose (FDG) uptake differences of specific brain regions according to wandering patterns were compared to those of non-wanderers. Results: In patients with pacing pattern, FDG PET showed significant lower FDG uptake in both middle cingulum and left putamen cluster compared to non-wanderers. The right precuneus and supplementary motor area in patients with random pattern and left calcarine sulcus, right calcarine sulcus, right middle cingulum, and right post central gyrus in patients with lapping pattern had significantly lower FDG uptake compared to non-wanderers. Conclusions: This study showed that wandering in patients with AD had three distinct patterns. These specific patterns showed significant lower FDG uptake in specific brain areas compared to non-wanderers.

• 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.