Evaluation of 18FDG PET-CT-positive mediastinal-hilar lymph nodes in extrathoracic malignancies by EBUS-TBNA; correlation of SUVmax, and short-axis diameter with the final diagnosis

Introduction: Intrathoracic lymph node metastasis from extrathoracic neoplasms are rare. Primary malignancies that metastasize to mediastinal-hilar lymph nodes are head and neck , carcinoma breast ,and genitourinary. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA)/endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is currently the preferred modality for mediastinal lymph node sampling. Methods: Fifty seven patients with extrathoracic malignancies with maximum standardized uptake value (SUVmax) of mediastinal-hilar lymph nodes greater than or equal to 2.5 were taken up for EBUS-TBNA. The histo-cytopathological results obtained from EBUS-TBNA were compared with SUVmax value and short-axis diameter of a lymph node as noted on EBUS. Results: Out of 74 sampled nodes, 49 (66.2%) were benign and 25 (33.8%) were malignant. The SUVmax range of benign nodes was 2.8� as compared to 3� of malignant nodes. The size range of malignant and benign nodes were 8� mm and 8� mm, respectively. The mean size of abnormal nodes (metastatic + granulomatous) was 17.5 (8� mm) and the mean SUVmax was 9.1 (3.4�), and it was a statistically significant difference when compared to reactive (normal) nodes. At SUVmax cut-off 7.5, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) were 78.5%, 81.2%, 84.6%, and 74.2%, respectively for detecting abnormal nodes. At 13 mm size cut-off, sensitivity, specificity, PPV, NPV were 75.5%, 65%, 75%, and 72%, respectively, for detecting abnormal nodes. Conclusion: The majority of mediastinal-hilar nodes with increased metabolic activity are benign in nature. Size and SUVmax are poor predictors of metastasis in tuberculosis endemic region. There should be a restrictive attitude toward invasive diagnostic testing for mediastinal-hilar nodes in extrathoracic malignancies.

Correlation of Early-Phase F-18 Florapronal PET with F-18 FDG PET in Alzheimer's Disease and Normal Brain / 대한핵의학회잡지

PURPOSE: F-18 florapronol (FPN) is the commercially recognized beta-amyloid positron emission tomography (PET) radiotracer in Korea. This study compared the early F-18 florapronol PET with F-18 fluorodeoxyglucose (FDG) PET between healthy controls (HC) and Alzheimer's dementia (AD) patients.METHODS: A total of 29 subjects (15 HC and 14 AD subjects) underwent F-18 FPN PET and F-18 FDG PET. F-18 FDG PET image was acquired from 30 to 60 min and F-18 FPN PET for 0 to 10 min. F-18 FPN and F-18 FDG images were spatially normalized with transformation matrices obtained from individual CTimages and standardized uptake value ration (SUVR) from cerebellum area, and the global mean was calculated using PMOD 3.6. Pearson's correlation coefficients between F-18 FDG and early F-18 FPN for predefined cortical brain regions were calculated.RESULTS: We compared the F-18 FDG and F-18 FPN for SUVR of a specific region in global mean normalization and cerebellum normalization, and most of the correlation coefficient was higher in global mean normalization. In global mean normalization, the correlation coefficient for SUVR of HC was higher than that of AD in all brain regions.CONCLUSIONS: Early F-18 FPN study can be used as a proxy marker for the F-18 FDG PET.

How Do the More Recent Reconstruction Algorithms Affect the Interpretation Criteria of PET/CT Images? / 대한핵의학회잡지

PURPOSE: Recently, a new Bayesian Penalized Likelihood (BPL) Reconstruction Algorithm was introduced by GE Healthcare, Q.Clear; it promises to provide better PET image resolution compared to the widely used Ordered Subset Expectation Maximization (OSEM). The aimof this study is to compare the performance of these two algorithms on several types of findings, in terms of image quality, lesion detectability, sensitivity, and specificity.METHODS: Between September 6th 2017 and July 31st 2018, 663 whole body 18F-FDG PET/CT scans were performed at the Nuclear Medicine Department of S. Martino Hospital (Belluno, Italy). Based on the availability of clinical/radiological follow-up data, 240 scans were retrospectively reviewed. For each scan, a hypermetabolic finding was selected, reporting both for OSEM and Q.Clear: SUVmax and SUVmean values of the finding, the liver and the background close to the finding; size of the finding; percentage variations of SUVmax and SUVmean. Each finding was subsequently correlated with clinical and radiological follow-up, to define its benign/malignant nature.RESULTS: Overall, Q.Clear improved the SUVvalues in each scan, especially in small findings (< 10mm), high SUVmax values (≥ 10), and medium/low backgrounds. Furthermore, Q.Clear amplifies the signal of hypermetabolic findings without modifying the background signal, which leads to an increase in signal-to-noise ratio, improving overall image quality. Finally, Q.Clear did not affect PET sensitivity or specificity, in terms of number of reported findings and characterization of their nature.CONCLUSIONS: Q.Clear is an iterative algorithm that improves significantly the quality of PET images compared to OSEM, increasing the SUVmax of findings (in particular for small findings) and the signal-to-noise ratio. However, due to the intrinsic characteristics of this algorithm, it will be necessary to adapt and/or modify the current interpretative criteria based of quantitative evaluation, to avoid an overestimation of the disease burden.

Characterization of adrenal masses with non-enhanced CT and 18F FDG-PET in patients with primary malignancies

Background: Characterizing adrenal lesions in patients with a known primary malignancy has a vital role in treatment and prognostication. A study by Gufler et al proposed a scoring system based on density, contour, homogeneity and size and found a high accuracy in differentiating adrenal adenomas from metastasis in patients with a known malignancy. This study evaluates the sensitivity and specificity of this NECT scoring system and comparing it with that of 18F FDG PET.Methods: The study was conducted on patients with diagnosed malignancies with adrenal mass, referred for 18F-FDG PET-CT scanning as a part of work up or follows up between October 2014 and March 2016. Whole-body CT and PET images were obtained using standard protocol. NECT scoring and quantitative analysis of FDG uptake in the adrenal lesions (SUVavg analysis) is done separately.Results: Of the 50 patients studied, 33 patients had benign adrenal lesions and the rest had metastatic lesions. Most common site of primary was lung. NECT score yielded a sensitivity of 88.2%, specificity of 100% and positive predictive value of 100%. SUVavg analysis yielded a 100% sensitivity, specificity and positive predictive value. Comparison of the predictive power of the two tests showed a z score of 2.5 and p value of 0.0124.Conclusions: 18-FDG PET can be considered as a gold standard for differentiating between metastasis and benign lesions of adrenal glands in patients with known primary. NECT has a comparable specificity as that of FDG PET, however with lower sensitivity.

Transiently Altered Distribution of F-18 FDG in a Patient with Subacute Thyroiditis / 대한핵의학회잡지

F-18 fluorodeoxyglucose (FDG) is a highly influential radiotracer that provides valuable information in many cancer types. However, the normal biodistribution of F-18 FDG is often variable and can be altered by intrinsic or iatrogenic factors. We report a case of diffuse symmetrically increased skeletal muscle uptake and relatively decreased hepatic uptake on F-18 FDG PET/CT in a 57-year-old female with pulmonary adenocarcinoma. Detailed clinical evaluation and retrospective radiologic evaluation revealed that she had been diagnosed with subacute thyroiditis 2 weeks ago. After 6 weeks, F-18 FDG distribution was normalized at the follow-up PET/CT study.

Clinical Significance of Pretreatment FDG PET/CT in MIBG-Avid Pediatric Neuroblastoma / 대한핵의학회잡지

PURPOSE: ¹⁸F-fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging is well known to have clinical significance in the initial staging and response evaluation of the many kinds of neoplasms. However, its role in the pediatric neuroblastoma is not clearly defined. In the present study, the clinical significance of FDG-PET/computed tomography (CT) in ¹²³I- or ¹³¹I-metaiodobenzylguanidine (MIBG)-avid pediatric neuroblastoma was investigated.METHODS: Twenty patients with neuroblastoma who undertook pretreatment FDG PET/CT at our institute between 2008 and 2015 and showed MIBG avidity were retrospectively enrolled in the present study. Clinical information—including histopathology, and serum markers—and several PET parameters—including SUVmax of the primary lesion (Psuv), target-to-background ratio (TBR), metabolic tumor volume (MTV), and coefficient of variation (CV)—were analyzed. The prognostic effect of PET parameters was evaluated in terms of progression-free survival (PFS).RESULTS: Total 20 patients (4.5 ± 3.5 years) were divided as two groups by disease progression. Six patients (30.0 %) experienced disease progression and one patient (5.0 %) died during follow-up period. There were not statistically significant in age, stage, MYCN status, primary tumor size, serum lactate dehydrogenase (LDH), neuron-specific enolase (NSE), and ferritin level between two groups with progression or no progression. However, Psuv (p = 0.017), TBR (p = 0.09), MTV (p = 0.02), and CV (p = 0.036) showed significant differences between two groups. In univariate analysis, PFS was significantly associated with Psuv (p = 0.021) and TBR (p = 0.023).CONCLUSIONS: FDG-PET parameters were significantly related with progression of neuroblastoma. FDG-PET/CT may have the potential as a valuable modality for evaluating prognosis in the patients with MIBG-avid pediatric neuroblastoma.

Custo-efetividade do uso da tomografia de emissão de pósitrons na detecção de recorrência do câncer diferenciado de tireoide / Cost-effectiveness of the use of positron emission tomography in the detection of recurrence of differentiated thyroid cancer

Avaliou-se a custo-efetividade da adição da tomografia de emissão de pósitrons (18FDG-PET-TC) aos métodos convencionais na detecção de recorrência de cânceres diferenciados de tireoide. O modelo analítico de decisão representou coorte hipotética de pacientes adultos, de alto risco pela estratificação inicial, submetidos a tireoidectomia total e ablação com I131. A estratégia convencional de detecção foi comparada à adição da 18FDG-PET-TC aplicada aos indivíduos com resultados de cintigrafia com I131 negativos. O horizonte temporal foi de dez anos. Utilizou-se a perspectiva do Sistema Único de Saúde (SUS) e, como medida de efetividade, os casos adicionais diagnosticados pela inclusão da PET-TC. Foram considerados apenas os custos médicos diretos. O custo do PET-TC foi estimado por microcustos; os demais custos foram obtidos das tabelas de pagamento de procedimentos do SUS. Custos e benefícios foram descontados em 5%. Realizaram-se análises de sensibilidade determinística univariada e probabilística. Detectaram-se 1.875 casos de recorrência com a estratégia convencional. Uso da 18FDG-PET-TC permitiu a detecção adicional de 13 casos, com custo de R$477.633,05/caso detectado. Os parâmetros de maior impacto na análise foram: medidas de acurácia dos métodos convencionais, custo do PET-TC e taxa de desconto. Os custos da adição da PET-TC mostram-se significativos e sua introdução não é custo-efetiva.

The positron emission tomography (18FDG-PET/CT) was recently introduced in Brazilian health care for many oncology indications but accompanied by higher costs. In our study we performed a cost-effectiveness analysis of the addition of PET/CT to the conventional diagnostic work-up to detect recurrent differentiated thyroid cancers. The analytical decision model represented a hypothetical cohort of adults, thyroid cancer patients with high risk by initial stratification, submitted to total thyroidectomy and ablation with I131. The addition of PET/CT was applied to subjects with negative results on I131scintigraphy. The model was designed from the perspective of the Brazilian public health care system, with a time horizon of 10 years. Effectiveness was measured by the additional recurrent cases detected. Only direct medical costs were considered. Costs and benefits were discounted by 5%. Univariate deterministic and probabilistic sensitivity analyzes were performed to explore the uncertainties. The PET/CT diagnosed 13 additional cases compared to conventional strategy (1,888 vs 1,875) by a cost of R$477,633.05 per case detected. The parameters of greatest impact in the sensitivity analysis were the accuracy of conventional tests, cost of PET/CT and the discount rate. The costs of adding PET/CT seems significant and its introduction is not cost-effective on the Brazilian perspective.

Estimation of radiation dose to patients from 18FDG whole body PET/CT investigations using dynamic PET scan protocol.

Background & objectives: There is a growing concern over the radiation exposure of patients from undergoing 18FDG PET/CT (18F-fluorodeoxyglucose positron emission tomography/computed tomography) whole body investigations. The aim of the present study was to study the kinetics of 18FDG distributions and estimate the radiation dose received by patients undergoing 18FDG whole body PET/CT investigations. Methods: Dynamic PET scans in different regions of the body were performed in 49 patients so as to measure percentage uptake of 18FDG in brain, liver, spleen, adrenals, kidneys and stomach. The residence time in these organs was calculated and radiation dose was estimated using OLINDA software. The radiation dose from the CT component was computed using the software CT-Expo and measured using computed tomography dose index (CTDI) phantom and ionization chamber. As per the clinical protocol, the patients were refrained from eating and drinking for a minimum period of 4 h prior to the study. Results: The estimated residence time in males was 0.196 h (brain), 0.09 h (liver), 0.007 h (spleen), 0.0006 h (adrenals), 0.013 h (kidneys) and 0.005 h (stomach) whereas it was 0.189 h (brain), 0.11 h (liver), 0.01 h (spleen), 0.0007 h (adrenals), 0.02 h (kidneys) and 0.004 h (stomach) in females. The effective dose was found to be 0.020 mSv/MBq in males and 0.025 mSv/MBq in females from internally administered 18FDG and 6.8 mSv in males and 7.9 mSv in females from the CT component. For an administered activity of 370 MBq of 18FDG, the effective dose from PET/CT investigations was estimated to be 14.2 mSv in males and 17.2 mSv in females. Interpretation & conclusions: The present results did not demonstrate significant difference in the kinetics of 18FDG distribution in male and female patients. The estimated PET/CT doses were found to be higher than many other conventional diagnostic radiology examinations suggesting that all efforts should be made to clinically justify and carefully weigh the risk-benefit ratios prior to every 18FDG whole body PET/CT scan.

Diagnostic value of 18 FDG-PET/CT for poorly differentiated gastric adenocarcinoma / 医学研究生学报

Objective The sensitivity and specificity of 18 FDG PET/CT are poor in the diagnosis of gastric cancer .Gastric signet ring cell carcinoma and Mucinous gastric carcinoma is known to have low fluorodeoxyglucose (18FDG) uptake,but not known for poorly differentiated gastric adenocarcinoma .This study was to investigate the value of 18 FDG PET/CT in the diagnosis of poorly differ-entiated gastric adenocarcinoma . Methods We retrospectively analyzed the results of 18 FDG PET/CT of 34 cases of histologically confirmed poorly differentiated gastric adenocarcinoma .We recorded the volume , location , and gastric wall invasion depth , and maxi-mum standardized uptake value ( SUVmax) of the tumors and analyzed the relationship of 18 FDG uptake with the clinicopathologic pa-rameters. Results By 18 FDG-PET/CT, poorly differentiated gastric adenocarcinoma was diagnosed in only 67.6% of the patients (23/34).SUVmax was found to be significantly correlated with age , gastric wall invasion, and tumor size (P0 .05 ) .Logistic regression a-nalysis showed the tumor size to be the sole factor influencing the 18 FDG uptake of poorly differentiated gastric adenocarcinoma ( OR=0.37, 95%CI 0.154-0.920, P=0.03). Conclusion The di-agnostic value of 18 FDG-PET/CT is but limited for poorly differentia-ted gastric adenocarcinoma , and attention should be paid to its false-negative results .

Tomografia por emissão de pósitrons com FDG-18F na avaliação de pacientes com artrite reumatoide - revisão sistemática / Positron emission tomography with 18F-FDG in the evaluation of patients with rheumatoid arthritis - a systematic review

Introdução A artrite reumatoide (AR) é uma doença caracterizada pela inflamação da membrana sinovial. Diversos autores têm investigado o papel da tomografia por emissão de pósitrons (PET) com flúor-18 (FDG-18F) na AR. Objetivos Revisão sistemática da literatura atual sobre o papel do PET com FDG-18F no diagnóstico, determinação da atividade da doença e avaliação da resposta ao tratamento em pacientes com AR. Métodos Foram realizadas buscas nas bases de dados Medline, Biblioteca Cochrane, Lilacs, Pubmed e Scopus nos idiomas português, inglês e espanhol, utilizando as palavras-chave «artrite reumatoide¼, «sinovite¼, «FDG¼, «PET¼, «metabolismo glicolítico¼ e «atividade da doença¼. Resultados 142 artigos foram inicialmente identificados, dos quais apenas 40 relacionavam-se diretamente ao tema. Foram selecionados 12 artigos originais e três relatos de caso que preenchiam os critérios de inclusão. Discussão A presença de fibroblastos e macrófagos ativados no pannus é responsável pela intensa captação periarticular de FDG-18F. Os padrões de captação não permitem o diagnóstico diferencial com outras artrites. A intensidade de captação e o número de articulações envolvidas são parâmetros metabólicos de atividade da doença que apresentam boa correlação com os índices compostos. Estudos longitudinais de PET têm se mostrado úteis na avaliação da resposta ao tratamento com anti-TNF. Quando realizado precocemente, PET pode predizer a resposta terapêutica. Conclusão Embora o real papel dessa nova técnica na investigação da AR ainda não esteja estabelecido, PET com FDG-18F é uma ferramenta ...

Introduction Rheumatoid arthritis (RA) is a disease characterized by inflammation of the synovial membrane. Several authors have investigated the role of positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (18F-FDG) in RA. Objectives To systematically review the current literature on the role of 18F-FDG PET in the diagnosis, determination of disease activity and assessment of treatment response in patients with RA. Methods Searches were conducted in Medline, Cochrane Library, Lilacs, Pubmed and Scopus in Portuguese, English and Spanish languages, using the keywords «rheumatoid arthritis¼, «synovitis¼, «FDG¼, «PET¼, «glycolytic metabolism¼ and «disease activity¼. Results One hundred and forty-two articles were initially identified, of which only 40 were related directly to the subject. Twelve original articles and three case reports that met the inclusion criteria were selected. Discussion The presence of activated macrophages and fibroblasts in pannus are responsible for the intense periarticular uptake of 18F-FDG. The uptake patterns do not allow the differential diagnosis with other arthritides. The uptake intensity and the number of joints involved are metabolic parameters of disease activity that correlate well with the composite indices. Longitudinal studies of PET have proven useful in assessing the response to treatment with anti-TNF. When performed early, PET can predict the therapeutic response. Conclusion Although the actual role of this new technique for the investigation of RA is not yet established, 18F-FDG PET is a promising tool in determining the activity and prediction of response to treatment of patients with RA. .

The suitable uptake value threshold of 18F-FDG PET/CT image on gross tumor volume delineation of nasopharyngeal carcinoma / 中华放射医学与防护杂志

Objective To define a suitable threshold setting for gross tumor volume (GTV)when using 18F-fluoro-deoxyglucose positron emission tomography and computed tomogram (PET/CT) for radiotherapy planning in Nasopharyngeal carcinoma(NPC).Methods Sixteen NPC patients respectively received PET/CT and MRI scan before their radiation treatment.All of the images were transferred to the radiotherapy planning system (TPS).MRI/CT-based primary GTV was defined as GTVf.Biological target volumes (BTVs) were derived from PET/CT-based GTVs of primary tumors.The BTVs were defined as the volumes when adjusting different percentage of the maximal standardized uptake value (SUVmax).GTVfs were compared with BTVs.The suitable threshold level (sTL) could be determined when BTV value and its morphology using a certain threshold level were observed to be the fittest GTVf.The suitable standardized uptake value (sSUV) was calculated as the sTL multiplied by the SUVmax.Results Our result demonstrated no single sTL or sSUV method could achieve an optimized volumetric match with the GTVf.The sTL was [20.93％±6.51％(15％-40％)],whereas the sSUV was [2.27±0.48(1.56-3.25)].The sTL was inversely correlated with the SUVmax sTL =-0.144ln(SUVmax) + 0.5548 (R2 =0.85,F =78.57,P＜0.01.The sSUV showed a linear correlation with the SUVmax sSUV =0.104(SUVmax) + 1.0398,(R2=0.75,F=41.88,P＜0.01).The sTL was not associated with the value of GTVf.Conclusions In PET/CT-based BTV for NPC,SUVmax threshold method is feasible.sTL is not a fixed value,which is correlated with the SUVmax instead of the value of tumor.

PET-CT: tumores de cabeza y cuello. Ensayo pictórico y revisión de la literatura / PET-CT: Head and Neck Tumors. Picture essay and literature review

La PET-CT como modalidad diagnóstica es muy útil en la evaluación anatomofisiológica de la cabeza y el cuello. Proporciona una alta sensibilidad y especificidad en la estadificación de neoplasias primarias, la respuesta al tratamiento médico o quirúrgico y la detección de recurrencias. Dichas enfermedades representan un alto impacto sobre la mortalidad y morbilidad de los pacientes. El principal objetivo de esta publicación es hacer una revisión de los hallazgos en la PET-CT de los tumores más frecuentes de cabeza y cuello, con énfasis en los procesos malignos, estudiados en nuestra institución.

PET-CT as a diagnostic modality which is very useful in the anatomical-physiological assessment of the head and neck. It provides high sensitivity and specificity in the staging of primary tumors, the response to medical or surgical treatment and the detection of recurrences. These diseases represent a high impact on the mortality and morbidity in our patients. Our main objective is to review the findings on PET-CT of the most common head and neck tumors with an emphasis on malignancy which are studied in our institution.

Typical 18-FDG-PET/CT Findings of Polymyalgia Rheumatica: A Case Report

Polymyalgia rheumatica (PMR) is an inflammatory rheumatic condition characterized by generalized pain and morning stiffness in the shoulders, hip girdle, and neck. Since the pathogenesis of PMR is still uncertain, the diagnosis of PMR depends on clinical features. There have been several studies regarding radiological tools for the diagnosis of PMR. Recent studies using 18-FDG-PET showed bursitis, synovitis, uptake in the spinous process and asymptomatic large-vessel vasculitis in PMR patients. However, there was no report on the efficacy of 18-FDG-PET for diagnosis of PMR in Korea. Here, we are first reporting a case of a Korean patient with PMR, who had radiological findings including bursitis, synovitis, uptake in the spinous process and asymptomatic large-vessel vasculitis on 18-FDG-PET/CT.

F-18 Fluorodeoxyglucose PET/CT and Post Hoc PET/MRI in a Case of Primary Meningeal Melanomatosis

Primary meningeal melanomatosis is a rare, aggressive variant of primary malignant melanoma of the central nervous system, which arises from melanocytes within the leptomeninges and carries a poor prognosis. We report a case of primary meningeal melanomatosis in a 17-year-old man, which was diagnosed with 18F-fluorodeoxyglucose (F-18 FDG) PET/CT, and post hoc F-18 FDG PET/MRI fusion images. Whole-body F-18 FDG PET/CT was helpful in ruling out the extracranial origin of melanoma lesions, and in assessing the therapeutic response. Post hoc PET/MRI fusion images facilitated the correlation between PET and MRI images and demonstrated the hypermetabolic lesions more accurately than the unenhanced PET/CT images. Whole body F-18 FDG PET/CT and post hoc PET/MRI images might help clinicians determine the best therapeutic strategy for patients with primary meningeal melanomatosis.

FDG-PET/CT Complements Bone Scan with Respect to the Detection of Skip Metastasis of Osteosarcoma: A Case Report / 대한골관절종양학회지

Skip lesion is not uncommon feature in osteosarcoma and considered to be importantly associated with poor prognosis factor, and thus, should be excised with the main mass. The accurate pre-operative evaluation of the intramedullary extent of osteosarcoma is essential, because it determines the level of bone resection. Among the reliable detection methods, bone scan has a drawback of high rate of false negative results and regional MRI has a difficulty to cover the whole involved lesions without clinical suspicion. The authors report a case of osteosarcoma of the distal femur with a proximal skip lesion that was not detected by either regional MR imaging or by bone scan, but which was visualized by FDG-PET/CT.

Influence of radiation on endotoxin test using the PTS TM for 18-FDG radiopharmaceutical / Influência da radiação sobre o teste de endotoxina usando o PTS TM para 18 radiofármaco FDG

F-18 FDG (2-[18-F] fluoro-2-deoxy-D-glucose) is the most frequently used radiopharmaceutical for PET and PET CT imaging exams. The FDA recently approved the use of the PTS TM (Portable Test System) as an alternative to the standard test proposed by the United States Pharmacopeia using the LAL (Limulus Amebocyte Lysates), that takes longer to perform (about 1h) than the PTS TM (15 min). Recent studies have demonstrated that radiation could interfere with the PTS TM test. In order to study the effects of radiation on the PTS TM test and/or equipment, 27 batches of F-18 FDG produced in the Nuclear Engineering Institute were analyzed. The results showed that no direct correlation with radiation was found in any of the cases.

O FDG-18 é o radiofármaco mais utilizado nos exames de PET e PET CT. O FDA recentemente aprovou o uso do PTS TM (Portable Test System) como método alternativo ao teste padrão de endotoxina, proposto pela Farmacopéia Americana, considerando que no primeiro há um tempo de espera de 1 hora frente a somente 15 minutos do segundo. Estudo recentes demonstram que a radiação poderia interferir no teste do PTS TM. De modo a avaliar os efeitos da radiação no teste PTS TM foram analisados 27 lotes de F-18 FDG produzidos no Instituto de Engenharia Nuclear. Os resultados demonstraram que em todos os casos nenhuma correlação direta com a radiação foi observada.

An intense 18F-FDG pulmonary microfocus on PET without detectable abnormality on CT: A manifestation of an iatrogenic FDG pulmonary embolus

An incidental finding of an intense focus of 18F-Fluorodeoxyglucose (FDG) pulmonary uptake on positron emission tomography (PET) without detectable lesions on computed tomography (CT) is highly suggestive of FDG microembolus. Its microscopic nature means it is undetectable on CT. It is an artefact attributable to 18F-FDG-tracer contamination at the injection site. This paper reports a case of a 61 year-old lady with a past history of breast carcinoma, in whom follow-up PET/CT images demonstrated an incidental intense FDG pulmonary abnormality. A follow-up PET/CT seven months later demonstrated complete resolution of the abnormality.

Diagnostic Role of F-18 FDG PET/CT in the Follow-up of Patients with Colorectal Cancer: Comparison with Serum CEA, CA 19-9 Levels and Computed Tomography / 핵의학분자영상

PURPOSE: Early detection of recurrence is an important factor for long term survival of patients with colorectal cancer. Measurement of serum levels of CEA, CA 19-9, CT and PET/CT has been commonly used in the postoperative surveillance of colorectal cancer. The purpose of this study was to compare the diagnostic ability of PET/CT, tumor marker and CT for recurrence in colorectal cancer patients after treatment. MATERIALS AND METHODS: F-18 FDG PET/CT imaging was performed in 189 colorectal cancer patients who underwent curative surgical resection and/or chemotherapy. Measurement of serum levels of CEA, CA 19-9 and CT imaging were performed within 2 months of PET/CT examination. Final diagnosis of recurrence was made by biopsy, radiologic studies or clinical follow-up for 6 months after each study. RESULTS: Overall sensitivity, specificity of PET/CT was 94.7%, 91.1%, while those of serum CEA were 44.7% and 97.3%, respectively. Sensitivity and specificity were 94.2%, 90.4% for PET/CT and better than those of combined CEA and CA 19-9 measurement (52.1%, 88.5%) in 174 patients measured available both CEA and CA 19-9 data. In 115 patients with both tumor markers and CT images available, PET/CT showed similar sensitivity but higher specificity (92.9%, 91.3%) compared to combination of tumor markers and CT images (92.9%, 74.1%). CONCLUSION: PET/CT was superior for detection of recurred colorectal cancer patients compared with both CEA, CA 19-9, and even with combination of both tumor markers and CT. Therefore PET/CT could be used as a routine surveillance examination to detect recurrence or metastasis of colorectal cancer.

Two Cases of Peritoneal Tuberculosis Mimicking Peritoneal Carcinomatosis on F-18 FDG PET/CT / 핵의학분자영상

F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET/CT) plays an important role in diagnosis of malignant tumors and adds to conventional imaging in the staging of pertoneal carcinomatosis. However, false positive cases resulting from benign disease such as tuberculosis may occur. We report two cases of peritoneal tuberculosis on F-18 FDG PET/CT which showed multiple hypermetabolic foci in the mesentery and peritoneum with increased serum cancer antigen 125 (CA 125). Subsequent F-18 FDG PET/CT showed a disappearance of pathologic uptake following treatment with anti-tuberculosis drugs.

Comparison of F-18 FDG Radioacitivity to Determine Accurate Dose Calibrator Activity Measurements / 의학물리

Obviously, the administration of the prescribed amount of activity to the patient requires proper operation of the dose calibrator, which shall be verified by implementing the required quality control on the instrument. This investigation examined the accuracy and precision of dose calibrator activity measurement of the radiopharmaceutical F-18 FDG. To investigate the status of the nuclear medicine centers in Korea for the performance of dose calibrators, 10 centers providing PET/CT system services in Korea were inspected in 2008. We measured accuracy and precision in 10 equipments in consideration of PET/CT model, installation area, and installation time. According to the results of comparative analysis of 10 dose calibrators used to measure radioactivity of F-18 FDG, accuracy was -5.00~4.50% and precision was 0.05~0.45%, satisfying the international standards, which are accuracy +/-10% and precision +/-5%. This study demonstrated that, for accurate measurements, no adjustment is necessary for a dose calibrator setting when measuring different dose calibrators of F-18 FDG activity prescriptions.