• Nuclear Medicine and Molecular Imaging
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• v.42 no.sup1
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• pp.126-129
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• 2008

Renal cell carcinoma is the most common histological type of renal malignancy, predominant in men and the primary treatment modality of this tumor is surgery. The role of diagnostic imaging in the management of this tumor is the evaluation of extent of disease as well as the detection and characterization of renal mass. US has long been a routine screening tool for kidney but tomographic imaging modalities such as CT and MRI begin to be also commonly used these days. On the other hand, the sensitivity of $^{18}F-FDG-PET$ in detection of renal mass is relatively low because of inherent limitation caused by FDG excretion pathway despite avid uptake of FDG to tumor cell per se. Many studies revealed FDG PET scan could play an important role in detection of metastatic lesions although the sensitivity for the detection of primary lesion is not so high. Furthermore, development of PET/CT scanner will make it possible to expand the indication of FDG PET scan in this malignancy.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.4
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• pp.323-327
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• 2008

An esophageal leiomyoma is the most common benign tumor of the esophagus mainly occurred in intramural portion. Occasionaly, it is difficult to discriminate esophageal malignancy from large leiomyoma. Although F-18 FDG PET has been used for differentiating malignant from benign disease, false-positive cases have been reported. Recently, uterine leiomyoma has been reported to have relatively high F-18 FDG uptake in some patients but little is known about how an esophageal leiomyoma might be showed on F-18 FDG PET. We report a case of esophageal leiomyoma that showed high FDG uptake on PET images.

• Kosin Medical Journal
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• v.33 no.3
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• pp.391-395
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• 2018

We report a case of a patient with locally advanced prostate cancer who had only lymph node involvement without bone metastasis on F-18 FDG PET/CT. A 62-year-old Korean male was admitted to our hospital due to dysuria. His PSA level on admission was 79.35 ng/mL. A transrectal ultrasound-guided prostate biopsy confirmed prostate cancer and his Gleason score was 10 (5+5). F-18 FDG PET/CT demonstrated a hypermetabolic mass lesion with SUVmax 7.0 in the prostate and hypermetabolism with SUVmax 4.7 of the abdominal and pelvic lymph nodes. Tc-99m HDP bone scan showed no significant bone metastasis. The patient underwent hormonal therapy for 9 months. Follow-up F-18 FDG PET/CT showed significantly reduced size and FDG uptake in the prostate and abdominal and pelvic lymph nodes. In this case, treatment monitoring with F-18 FDG PET/CT showed decreased mass size and FDG uptake in the prostate and abdominal and pelvic lymph nodes.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.1
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• pp.23-27
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• 2006

Purpose: There are a few case reports on asymmetric vocal cord uptake on FDG-PET in patients with unilateral vocal cord paralysis, which could be a potential pitfall in the interpretation of FDG-PET images. We evaluated the metabolic activity of laryngeal muscles of patients with unilateral vocal cord paralysis in comparison to normal controls during both speech and silence. Methods: Eleven patients with unilateral vocal cord palsy (thyroldectomy=7, lung cancer=1, others=3) and 12 normal controls underwent FDG-PET with usual protocol. They were divided into two groups respectively; one group read books aloud for 20 minutes (phonation group) and the other kept silence (non-phonation groups) after FDG injection. Recent neck CT scan were co-registered with FDG-PET to produce PET-CT fusion images to elaborate small laryngeal muscles. Results: In patients with unilateral vocal cord palsy, contralateral non-paralyzed vocal cord showed hypermetabolism mainly on thyroarytenoid muscle, more intensely with phonation group ($SUV=5.88{\pm}2.65$) than with non-phonation group ($SUV=2.30{\pm}0.39$). Normal control subjects showed hypermetabolism ($3.68{\pm}0.96$) in interarytenoid muscle and symmetric mild hypermetabolism in both lateral cricoarytenoid muscles in only phonation group. Conclusion: FDG-PET with fusion images using CT scan in patients with unilateral vocal cord paralysis showed hypermetabolism of contralateral non-paralyzed thyroarytenoid muscle, suggesting compensatory action during phonation. Phonation durung FDG PET study enhanced FDG uptake on different laryngeal muscles between patients with unilateral vocal cord paralysis and normal subjects.

• The Korean Journal of Nuclear Medicine
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• v.33 no.6
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• pp.466-474
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• 1999

Purpose: The purpose of this study was to evaluate the diagnostic accuracy of [$^{18}F$]FDG PET in the diagnosis of recurrent head and neck cancer after the completion of surgery and radiotherapy in patients with head and neck cancers. Materials and Methods: In fifty-nine patients with head and neck cancers whole body [$^{18}F$]FDG PET studies were performed. According to the different therapeutic modalities, patients were divided into four groups (Group I; pre-treatment, Group II: surgery, Group III; radiotherapy, Group IV; both surgery and radiotherapy). [$^{18}F$]FDG PET images were compared with clinical, CT and histopathologic findings. Results: for detection of metastatic lymph nodes in 14 patients of pre-treatment group (group I), the sensitivity and specificity of PET were 100% (10/10) and 75% (3/4), and those of CT were 80% (8/10) and 100% (4/4). For detection of recurrence in 45 patients of post-treatment group, overall sensitivity and specificity of PET were 96.2% (25/26) and 78.9% (15/19) [(100% and 75% in group II, 80% and 10% in group III, and 100% and 100% in group IV)] without significant difference from pre-treatment group (P>0.1). In detecting recurrence, the sensitivity and specificity of [$^{18}F$]FDG PET were 90.9% (10/11) and 20% (1/5) in 16 patients who underwent [$^{18}F$]FDG PET within 2 months after the completion of treatment. The specificity of these patients was significantly lower than that of 29 patients (100% of sensitivity and specificity) who underwent [$^{18}F$]FDG PET 2 months after treatment (p<0.05). Conclusion: [$^{18}F$]FDG PET is an accurate diagnostic modality for the detection of recurrence in head and neck cancer. Post-therapy [$^{18}F$]FDG PET should be obtained at least 2 months after the completion of surgery or radiotherapy.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.1
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• pp.8-12
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• 2010

Purpose: In $^{18}F$-FDG automated synthesizer, deliver is done in automated mode after synthesis until the dispenser. After the delivery, the yield is calculated from the radioactivity which was read by the dose calibrator located in the dispenser. However, when the distance between the automated synthesizer and the dispenser is far, there are $^{18}F$-FDG residues, which results in loss of the amount of $^{18}F$-FDG. This study investigated the usefulness of a method that minimizes $^{18}F$-FDG residues. Materials and Methods: The structure of the tubing between the (TRACERlab Mx FDG; GE.) and the dispenser is that the distance is 8 m and the internal diameter is 1/16 inch. The synthesis process of The module goes through the synthesis process of trap, synthesis, delivery in the automated module. The time taken for synthesis is about 25 to 26 minutes, after which rinsing is done. However, after rinsing, as the distance of the tubing increased, there were 10~13% of $^{18}F$-FDG residues. Therefore, a method of using push syringe and $N_2$ gas in manual mode to minimize $^{18}F$-FDG residues is analyzed. Results: In manual mode, there were $^{18}F$-FDG residues of 4~5% for the push syringe, and there were $^{18}F$-FDG residues of less than 1% for the $N_2$ gas, which showed that the method using $N_2$ gas had superior usefulness. Also, there were no $^{18}F$-FDG residues in the cleaning the next day. Conclusion: The distance between the synthesizer and the dispenser needs to be reduced as much as possible, to reduce the rate of loss of $^{18}F$-FDG resulting from the distance of the tubing. However, in case the distance between the synthesizer and the dispenser has to be increased due to the system structure, using push syringe and $N_2$ gas simultaneously is a useful method for minimizing $^{18}F$-FDG residues.

• Journal of Gastric Cancer
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• v.18 no.3
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• pp.218-229
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• 2018

Purpose: This study investigated whether the metabolic avidity of primary tumors and/or metastatic lymph nodes (LNs) measured by $^{18}F$-fluorodeoxyglucose ($^{18}F-FDG$) positron emission tomography/computed tomography (PET/CT) was related to survival after surgery in patients with advanced gastric cancer (AGC). Materials and Methods: One hundred sixty-eight patients with AGC who underwent preoperative $^{18}F-FDG$ PET/CT and curative resection were included. The $^{18}F-FDG$ avidity of the primary gastric tumor and LNs was determined quantitatively and qualitatively. The diagnostic performance of $^{18}F-FDG$ PET/CT was calculated, and the prognostic significance of $^{18}F-FDG$ avidity for recurrence-free survival (RFS) and overall survival (OS) was assessed. Results: In all, 51 (30.4%) patients experienced recurrence, and 32 (19.0%) died during follow-up (median follow-up duration, 35 months; range, 3-81 months); 119 (70.8%) and 33 (19.6%) patients showed $^{18}F-FDG$-avid primary tumors and LNs, respectively. $^{18}F-FDG$ PET/CT showed high sensitivity (73.8%) for the detection of advanced pathologic T ($pT{\geq}3$) stage and high specificity (92.2%) for the detection of advanced pN (${\geq}2$) stage. $^{18}F-FDG$ avidity of LNs was significantly associated with RFS (P=0.012), whereas that of primary tumors did not show significance (P=0.532). Univariate and multivariate analyses revealed that $^{18}F-FDG$ avidity of LNs was an independent prognostic factor for RFS (hazard ratio=2.068; P=0.029). Conclusions: $^{18}F-FDG$ avidity of LNs is an independent prognostic factor for predicting RFS. Preoperative $^{18}F-FDG$ PET/CT can be used to determine the risk and prognosis of patients with AGC after curative resection.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.5
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• pp.369-385
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• 2009

In this paper, the authors intended to summarize briefly the features of lymphoma with regard to $^{18}F$-FDG PET for assessment of tumor response to therapy, to describe why assessment of treatment response should be performed, to review what method so far has been used in monitoring treatment response, to discuss what limitations of morphologic imaging criteria for assessing tumor response are, in compared with $^{18}F$-FDG PET, and to introduce recently proposed criteria for assessing tumor response in malignant lymphoma. And also the authors emphasize the need to understand the characteristics of diagnostic performance of $^{18}F$-FDG PET in several clinical settings in order to interpret $^{18}F$-FDG PET results appropriately, and to encourage the use of interval likelihood ratio to enhance clinical implications of test results which, in turns, allows referring physicians to understand the meaning of interpretation with easy. Until recently, treatment response has been assessed according to the morphologic criteria. Metabolic imaging with $^{18}F$-FDG PET was adopted to have important role for treatment assessment in IWC+PET criteria proposed recently by IHP. To accomplish this role, we should perform and interpret $^{18}F$-FDG PET according to IWC+PET criteria. It is important for referring physicians to understand the various limitations of $^{18}F$-FDG PET and pitfalls in PET interpretation, and to understand that clinical information are needed by nuclear medicine physicians to optimize the interpretation of $^{18}F$-FDG PET.

• The Korean Journal of Nuclear Medicine Technology
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• v.12 no.3
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• pp.184-191
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• 2008

Purpose: To evaluate the degree of malignancy of incident thyroid lesion found in $^{18}F$-FDG PET/CT findings and the usefulness of the method suggested in this study, we applicate the Delay Scan Method that differentiate a false positive benign tumor, inflammation and malignancy, as well as make the criteria of SUV. Materials and Methods: A retrograde study was conducted of 800 patients who were admitted in E hospital to receive $^{18}F$-FDG PET/CT examination. One patient who was diagnosed as primary thyroid cancer and received $^{18}F$-FDG PET/CT examination was excluded. The number of final patients of this study was 799, the reasons of $^{18}F$-FDG PET/CT examination of these patients were follow-up of old cancer or suspicious tumorous lesion in 696 and disease screening in 103. $^{18}F$-FDG PET/CT image photographing was taken in Biograph-Duo made by SIEMENS, after taking normal $^{18}F$-FDG PET/CT image (1 hr) and then 1 hr later we took the thyroid 1 bed-delayed image for the patients who showed abnormal thyroid $^{18}F$-FDG uptake and above 2.0 SUV for 2 minutes every 1 bed. For the patients who showed abnormal thyroid uptake and above 2.0 SUV, 1 hr later, we took a 1 bed-delayed image and then made a comparative study between measured $SUV_{max}$ of 1 hr-abnormal uptake image and that of 2 hr-delayed image. Results and Conclusion: In this $^{18}F$-FDG PET/CT study among the patients who showed incidental $^{18}F$-FDG thyroidal uptake the number of thyroid incidentaloma was 5 (0.63%), all of then showed benign findings. And in the case of incidental $^{18}F$-FDG uptake in thyroid, $SUV_{max}$ variance obtained from 2 hr delayed image can be a indirect criteria in differentiating benign tumor from malignancy and decrease finding error. In the cases found thyroid incidentaloma when 1) $SUV_{max}$ of focal thyroid lesion is above 5.0 and 2) $SUV_{max}$ variance between normal $^{18}F$-FDG PET/CT exam and 2 hr delayed is $1.0{\pm}0.5$, they are suspected as malignancy and confirming biopsy is to be followed. Otherwise, I also think that distinct follow-up PET or CT image study is a reasonable diagnostic method.

• The Korean Journal of Nuclear Medicine
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• v.37 no.3
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• pp.171-177
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• 2003

PURPOSE: To asess the ability of FDG PET for the detection of bone marrow infiltration compared to iliac crest biopsy in patients with lymphoma. MATERIALS AND METHODS: Seventy-three patients (30 females and 43 males, mean age of 47 years old) with malignant lymphoma (4 Hodgkin's disease, HD and 69 Non-Hodgkin's lymphoma, NHL) were included. FDG PET was performed for staging in 53 patients and to assess treatment response after the completion of chemotherapy in 20 patients. Final conclusions were based on biopsy, other imaging studies, or clinical follow-up. RESULTS: There were 54 (74%) of the 73 patients in whom FDG PET and iliac crest biopsy were concordant. Forty-seven of the 54 patients showed concordant negative results while the remaining 7 patients had concordant positive results. Of 19 patients with discordant results, FDG PET accurately detected bone marrow infiltration in 6 patients with negative iliac crest biopsy. On the contrary, iliac crest biopsy identified bone marrow infiltration in 12 or the 19 patients. In remaining one of the 19 patients with discordant results, iliac crest biopsy was true negative but FDG PET was falsely positive. CONCLUSION: FDG PET seems to be an adjunct in detecting marrow infiltration that may not be revealed by iliac crest biopsy at staging. For the assessment of treatment roponse, it may be less helpful than biopsy in detecting microscopic residual disease in the bone marrow.