• The Korean Journal of Nuclear Medicine
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• v.36 no.1
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• pp.87-89
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• 2002

A 30 year-old female patient with papillary thyroid carcinoma received her fifth radioiodine ablation therapy after the subtotal thyroidectomy. The scan, which was peformed one week after the last therapy, revealed residual uptake in the thyroid bed and uptake in the anterior mediastinum suggesting metastasis. However, further evaluation of the thorax with chest CT and camera-based FDG PET confirmed normal thymus without metastatic focus. Occasionally thymus remains intact in adult and has avidity for I-131 and FDG. Therefore, normal thymus (instead of metastasis) should be considered in patients with well differentiated thyroid carcinoma and anterior mediastinal radioiodine uptake.

• Korean Journal of Radiology
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• v.24 no.11
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• pp.1142-1150
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• 2023

Objective: To evaluate ^99mtechnetium-three polyethylene glycol spacers-arginine-glycine-aspartic acid (^99mTc-3PRGD₂) single-photon emission computed tomography (SPECT)/computed tomography (CT) imaging for diagnosing lymph node metastasis of primary malignant lung neoplasms. Materials and Methods: We prospectively enrolled 26 patients with primary malignant lung tumors who underwent ^99mTc-3PRGD₂ SPECT/CT and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/CT imaging. Both imaging methods were analyzed in qualitative (visual dichotomous and 5-point grades for lymph nodes and lung tumors, respectively) and semiquantitative (maximum tissue-to-background radioactive count) manners for the lymph nodes and lung tumors. The performance of the differentiation of lymph nodes with and without metastasis was determined at the per-lymph node station and per-patient levels using histopathological results as the reference standard. Results: Total 42 stations had metastatic lymph nodes and 136 stations had benign lymph nodes. The differences between metastatic and benign lymph nodes in the visual qualitative and semiquantitative analyses of ^99mTc-3PRGD₂ SPECT/CT and ¹⁸F-FDG PET/CT were statistically significant (all P < 0.001). The area under the receiver operating characteristic curve (AUC) in the semi-quantitative analysis of ^99mTc-3PRGD₂ SPECT/CT was 0.908 (95% confidence interval [CI], 0.851-0.966), and the sensitivity, specificity, positive predictive value, and negative predictive value were 0.86 (36/42), 0.88 (120/136), 0.69 (36/52), and 0.95 (120/126), respectively. Among the 26 patients (including two patients each with two lung tumors), 15 had pathologically confirmed lymph node metastasis. The difference between primary lung lesions in patients with and without lymph node metastasis was statistically significant only in the semi-quantitative analysis of ^99mTc-3PRGD₂ SPECT/CT (P = 0.007), with an AUC of 0.807 (95% CI, 0.641-0.974). Conclusion: ^99mTc-3PRGD₂ SPECT/CT imaging may notably perform in the direct diagnosis of lymph node metastasis of primary malignant lung tumors and indirectly predict the presence of lymph node metastasis through uptake in the primary lesions.

• Journal of Digestive Cancer Research
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• v.5 no.2
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• pp.91-96
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• 2017

Background: To evaluate whether DM affects the SUVmax of metastatic lesions on ¹⁸F-FDG PET/CT and whether the SUVmax can influence the prognosis of metastatic PDAC patients. Methods: We conducted a retrospective study of 86 patients with metastatic PDAC who underwent PET/CT before treatment. The SUVmax of primary and metastatic lesions and the ratios of the SUVmax were measured. Long-term survival was evaluated using clinical parameters. Results: The mean SUVmax of primary lesion was lower in the DM group than in the non-DM group (4.74 vs. 5.96, p=0.009). The SUVmax for all metastatic lesions, except those in the lung, were lower in the DM group than in the non-DM group, and these differences were statistically significant in the lymph nodes and peritoneum. In the 35 patients with hepatic metastasis, higher ratios of the liver SUVmax significantly correlated with shorter OS (HR, 2.625; p=0.013). Conclusion: DM can influence the lower SUVmax of metastatic lesions as well as primary lesions. The SUVmax ratio of hepatic metastasis could influence on prognosis in metastatic PDAC patients.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.2925-2929
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• 2013

Objective: To explore the relationships between primary tumor $^{18}F$-FDG uptake measured as the SUVmax and local extension, and nodal or distant organ metastasis in patients with NSCLC on pretreatment PET-CT. Methods: 93 patients with NSCLC who underwent $^{18}F$-FDG PET-CT scans before the treatment were included in the study. Primary tumor SUVmax was calculated; clinical stages, presence of local extension, nodal and distant organ metastases were recorded. The patients with SUVmax${\geq}2.5$ were divided into low and high SUVmax groups by using the median SUVmax. The low SUVmax group consisted of 45 patients with SUVmax<10.5, the high SUVmax group consisted of 46 patients with SUVmax${\geq}10.5$. Their data were compared statistically. Results: 91 cases with SUVmax${\geq}2.5$ were included for analysis. The mean SUVmax in patients without any metastasis was $7.42{\pm}2.91$ and this was significantly lower than that ($12.18{\pm}4.94$) in patients with nodal and/or distant organ metastasis (P=0.000). In the low SUV group, 19 patients had local extension, 22 had nodal metastasis, and 9 had distant organ metastasis. In the high SUV group, 31 patients had local extension, 37 had nodal metastasis, and 18 had distant organ metastases. There was a significant difference in local extension (P =0.016), distant organ metastasis (P =0.046), and most significant difference in nodal metastasis rate (P =0.002) between the two groups. In addition, there was a moderate correlation between SUVmax and tumor size (r = 0.642, P<0.001), tumor stage (r = 0.546, P<0.001), node stage (r = 0.388, P<0.001), and overall stage (r = 0.445, P= 0.000). Conclusion: Higher primary tumor SUVmax predicts higher extensional or metastatic potential in patients with NSCLC. Patients with higher SUVmax may need a close follow-up and more reasonable individual treatment because of their higher extensional and metastatic potential.

• Korean Journal of Radiology
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• v.25 no.2
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• pp.189-198
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• 2024

Objective: To investigate the prognostic utility of radiomics features extracted from ¹⁸F-fluorodeoxyglucose (FDG) PET/CT combined with clinical factors and metabolic parameters in predicting progression-free survival (PFS) and overall survival (OS) in individuals diagnosed with extranodal nasal-type NK/T cell lymphoma (ENKTCL). Materials and Methods: A total of 126 adults with ENKTCL who underwent ¹⁸F-FDG PET/CT examination before treatment were retrospectively included and randomly divided into training (n = 88) and validation cohorts (n = 38) at a ratio of 7:3. Least absolute shrinkage and selection operation Cox regression analysis was used to select the best radiomics features and calculate each patient's radiomics scores (RadPFS and RadOS). Kaplan-Meier curve and Log-rank test were used to compare survival between patient groups risk-stratified by the radiomics scores. Various models to predict PFS and OS were constructed, including clinical, metabolic, clinical + metabolic, and clinical + metabolic + radiomics models. The discriminative ability of each model was evaluated using Harrell's C index. The performance of each model in predicting PFS and OS for 1-, 3-, and 5-years was evaluated using the time-dependent receiver operating characteristic (ROC) curve. Results: Kaplan-Meier curve analysis demonstrated that the radiomics scores effectively identified high- and low-risk patients (all P < 0.05). Multivariable Cox analysis showed that the Ann Arbor stage, maximum standardized uptake value (SUVmax), and RadPFS were independent risk factors associated with PFS. Further, β2-microglobulin, Eastern Cooperative Oncology Group performance status score, SUVmax, and RadOS were independent risk factors for OS. The clinical + metabolic + radiomics model exhibited the greatest discriminative ability for both PFS (Harrell's C-index: 0.805 in the validation cohort) and OS (Harrell's C-index: 0.833 in the validation cohort). The time-dependent ROC analysis indicated that the clinical + metabolic + radiomics model had the best predictive performance. Conclusion: The PET/CT-based clinical + metabolic + radiomics model can enhance prognostication among patients with ENKTCL and may be a non-invasive and efficient risk stratification tool for clinical practice.

• 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.

• The Korean Journal of Nuclear Medicine Technology
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• v.24 no.1
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• pp.15-19
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• 2020

Purpose Generative Adversarial Network(GAN) is one of deep learning technologies. This is a way to create a real fake image after learning the real image. In this study, after acquiring artificial intelligence images through GAN, We were compared and evaluated with real scan time images. We want to see if these technologies are potentially useful. Materials and Methods 30 patients who underwent ¹⁸F-FDG Brain PET/CT scanning at Severance Hospital, were acquired in 15-minute List mode and reconstructed into 1,2,3,4,5 and 15minute images, respectively. 25 out of 30 patients were used as learning images for learning of GAN and 5 patients used as verification images for confirming the learning model. The program was implemented using the Python and Tensorflow frameworks. After learning using the Pix2Pix model of GAN technology, this learning model generated artificial intelligence images. The artificial intelligence image generated in this way were evaluated as Mean Square Error(MSE), Peak Signal to Noise Ratio(PSNR), and Structural Similarity Index(SSIM) with real scan time image. Results The trained model was evaluated with the verification image. As a result, The 15-minute image created by the 5-minute image rather than 1-minute after the start of the scan showed a smaller MSE, and the PSNR and SSIM increased. Conclusion Through this study, it was confirmed that AI imaging technology is applicable. In the future, if these artificial intelligence imaging technologies are applied to nuclear medicine imaging, it will be possible to acquire images even with a short scan time, which can be expected to reduce artifacts caused by patient movement and increase the efficiency of the scanning room.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.1
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• pp.22-29
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• 2007

Purpose: Metastatic thyroid cancers with I-131 uptake have been known to show no increase of FDG uptake whereas those without I-131 uptake tend to demonstrate increased uptake on PET. In this study, we evaluated the degree of FDG uptake in primary thyroid cancers of papillary histology before surgery. Material & Methods: Forty FDG PET studies were performed on the patients who had papillary cancer proven by fine needle aspiration. The degree of FDG uptake was visually categorized as positive or negative (positive if the tumor showed discernible FDG; negative if the tumor didn't) and the peak standard uptake value (peak SUV) of the papillary thyroid cancer (PTC) were compared with the size of PTC. Results: The mean size of 26 PTC with positive FDG uptake was $1.9{\pm}1.4\;cm(0.5{\sim}5\;cm)$. In 13 PTC with negative FDG uptake, the mean size of those was $0.5{\pm}0.2\;cm\;(0.2{\sim}0.9\;cm)$. All PTC larger than 1cm ($2.5{\pm}1.4\;cm,\;1{\sim}5\;cm$) have positive FDG uptake (peak $SUV=6.4{\pm}5.7,\;1.7{\sim}22.7$). Among the micropapillary thyroid cancer (microPTC; PTC smaller than 1cm), 8 microPTC show positive FDG uptake(peak $SUV=2.9{\pm}1.3,\;1.7{\sim}5.5$), while 13 microPTC show negative finding(peak $SUV=1.3{\pm}0.2,\;1.1{\sim}1.7$). The size of microPTC with positive FDG uptake is significantly larger than that of microPTC with negative FDG uptake ($0.7{\pm}0.1\;cm$ vs $0.4{\pm}0.2\;cm$, p=0.01). Conclusion: All PTCs larger than 1cm show positive FDG uptake in our study. In other words, thyroid lesions larger than 1cm with negative FDG uptake are unlikely to be PTC. So far, only poorly differentiated thyroid cancers are known to show increased FDG uptake. Our results seem to be contradictory to what is known in the literature. Further study is needed to understand better the significance of increased FDG uptake in PTC in relation to expression of NIS and GLUT.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.44-49
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• 2012

Purpose: In the whole body PET/CT scan, it is natural to lift the patient's arm for its quality improvement. However, when the lesion is located in head and neck, the arms should be located lower. This study was designed to compare the CT effective dose for each arm position applying Automatic Exposure Control (AEC). Materials and Methods: 45 patients who had $^{18}F$-FDG whole body PET/CT scan were studied with Biograph Truepoint 40 (SIEMENS, GERMANY), Biograph Sensation 16 (SIEMENS, GERMANY), Discovery STe 8 (GE healthcare, USA). The CT effective dose of 15 patients for each equipment was measured and comparatively analyzed in both arm-lifted position and lower-arm position. ImPACT v1.0 program was used as the method of measurement for CT effective dose. For the statistics analysis, Paired t-test which paired with SPSS 18.0 statistic program was applied. Results: In the case of arm-lifted, it was measured as $6.33{\pm}0.93mSv$ for Biograph Sensation 16, $8.01{\pm}1.34mSv$ for Biograph Truepoint 40, and $9.69{\pm}2.32mSv$ for Discovery STe 8. When arms are located lower position, it was measure as $6.97{\pm}0.76mSv$, $8.95{\pm}1.85mSv$, $13.07{\pm}2.87mSv$ for each. CT effective dose according to the arm position was 9.2% for Biograph Truepoint 40, 10.5% for Biograph Sensation 16, and 25.9% for Discovery Ste 8. The statistics analysis showed the meaningful difference ($p$<0.05). Conclusion: For the whole body PET/CT case, CT effective dose applying AEC was decreased the radiation exposure of the patients when the arm was lifted for 15.2% of average value. The patient who has no lesion in head and neck would decrease the artifact occurrence in objective part and lower the CT effective dose. Also, for the patient who had lesion in head and neck, the artifact in objective part can be lower by putting the arms down, the fact that CT effective dose increases should be concerned in its whole body PET/CT scan.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.1
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• pp.3-7
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• 2010

Purpose: The usefulness of Positron Emission Tomography (PET) images in diagnosis, staging, recurrent and treatment response evaluation has already been known. However, tumors which are small size, located in lower lobe of lung or upper lobe of liver are shown misalignment, distortion and different Standard Uptake Value (SUV) by respiration in PET images. Therefore, if radiotherapy based on normal respiration, it may cause low treatment response or more side effects because targets which had to treat, out of treat range or over dose to normal tissue. The purpose of this study is to evaluate attenuation-correction with Average CT (ACT) for more accuracy SUV measurement and minimize artifact by respiration. Materials and Methods: 13 patients, who had tumors which are around the diaphragm, underwent ACT scan after Helical CT (HCT) scan with PET/CT (Discovery DSTE 8; GE Healthcare). We quantified the differences between attenuation corrected image with HCT and attenuation corrected image with ACT in artifact size and maximum SUV ($SUV_{max}$). Artifacts were evaluated by measurement of the curved photogenic area in the lower thorax of the PET images for all patients. $SUV_{max}$ was measured separately at the primary tumors. Analysis program was Advantage Workstation v4.3 (GE Healthcare). Patients were injected with 7.4 MBq (0.2 $mC_i$) per kg of $^{18}F$-FDG and scanned 1 hour after injection. The PET acquisition was 3 minute per bed. Results: Significantly lower artifact were observed in PET/ACT images than in PET/HCT images (below-thoracic artifacts caused by under corrected $1.5{\pm}3.5$ cm vs. $13.4{\pm}4.2$ cm). Significantly higher $SUV_{max}$ were noted in PET/ACT images than in PET/HCT images in the primary tumor. Compared with PET/HCT images, $SUV_{max}$ in PET/ACT images were higher by $5.3{\pm}3.9%$ (mean value) tumor. The highest difference was observed in Lower lobe of lung (7.7 to 8.7; 13%). Conclusion: Due to its significantly reduced artifacts in lower thoracic, attenuation corrected image with ACT images provided more reliable $SUV_{max}$ and may be helpful in monitoring treatment response. Moreover, ACT can separate upper lobe of liver and lower lobe of lung, it may be helpful in interpretation. ACT will be clinically useful, considering increased dose caused by ACT scan and adapt.