Imaging approach for early diagnosis, accurate staging, and the evaluation of treatment response has been consisted of anatomical and functional imaging methods. The anatomical image usually depends on high spatial resolution to distinguish morphological difference from normal anatomy, but altered anatomy is not a specific finding for malignancy. Moreover, it frequently needs other imaging modalities for systemic evaluation of disease. The functional image has been used for research and clinical purpose to overcome these shortcomings of the anatomical image, and the importance of functional evaluation of tumors is widely accepted by the introduction of Positron Emission Tomography (PET). Most of the PET systems at present are supplied as PET/CT combining functional and anatomical images, altogether. Especially for hepatobiliary tumors, showing a low sensitivity by PET alone, PET/CT will play an important role in determining TNM stage, deciding treatment modality, and evaluating treatment response. In addition, PET/CT as the most advanced molecular image technique has further growing potentials such as the development of a faster PET system, various new PET tracers, etc, which will contribute to improving patient survival and the quality of life.
Bile Duct Neoplasms ; Carcinoma, Hepatocellular ; Early Diagnosis ; Electrons* ; Humans ; Positron-Emission Tomography and Computed Tomography ; Positron-Emission Tomography* ; Quality of Life

PET 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 being diagnosed with 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 sensitivities for lymph node staging, the specificities 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 FDG uptake of the primary tumor is low, the distant metastasis is also known to show low FDG uptake reducing its detection. There are only a few data available in the evaluation of recurrence detection and treatment response using FDG PET.
Adult ; Blood Vessels ; Endoscopy ; Humans ; Lung ; Lymph Nodes ; Mass Screening ; Neoplasm Metastasis ; Positron-Emission Tomography and Computed Tomography* ; Recurrence ; Sensitivity and Specificity ; Stomach Neoplasms* ; Unnecessary Procedures

Aerobic glycolysis has been the most important hypothesis in cancer metabolism. It seems to be related to increased bioenergetic and biosynthetic needs in rapidly proliferating cancer cells. To this end, F-18 fluorodeoxyglucose (FDG), a glucose analog, became widely popular for the detection of malignancies combined with positron emission tomography/computed tomography (PET/CT). Although the potential roles of FDG PET/CT in primary tumor detection are not fully established, it seems to have a limited sensitivity in detecting early gastric cancer and mainly signet ring or non-solid types of advanced gastric cancer. In evaluating lymph node metastases, the location of lymph nodes and the degree of FDG uptake in primary tumors appear to be important factors affecting the diagnostic accuracy of PET/CT. In spite of the limited sensitivity, the high specificity of PET/CT for lymph node metastases may play an important role in changing the extent of lymphadenectomy or reducing futile laparotomies. For peritoneal metastases, PET/CT seems to have a poorer sensitivity but a better specificity than CT. The roles of PET/CT in the evaluation of other distant metastases are yet to be known. Studies including primary tumors with low FDG uptake or peritoneal recurrence seem suffer from poorer diagnostic performance for the detection of recurrent gastric cancer. There are only a few reports using FDG PET/CT to predict response to neoadjuvant or adjuvant chemotherapy. A complete metabolic response seems to be predictive of more favorable prognosis.
Chemotherapy, Adjuvant ; Electrons ; Energy Metabolism ; Glucose ; Glycolysis ; Laparotomy ; Lymph Node Excision ; Lymph Nodes ; Metabolism* ; Neoplasm Metastasis ; Positron-Emission Tomography and Computed Tomography* ; Prognosis ; Recurrence ; Sensitivity and Specificity ; Stomach Neoplasms*

No abstract available.
Nitriles ; Pyrethrins ; Sentinel Lymph Node Biopsy

PET using FDG has been proposed as a functional whole body imaging modality that images various types of malignancies with relatively high sensitivity and specificity in a reasonably short time. It depicts a lesion based on abnormal glucose metabolism whereas CT as a high-resolution anatomical imaging detects malignant process mostly based on altered anatomy. PET / CT combines the advantages of PET and CT, and has a great value in early detection of disease, accurate staging or restaging, early assessment of treatment response, decision on therapeutic plans, and rapid localization of recurrence. Exact anatomical localization of a lesion with increased FDG uptake by CT is considered to be the most important factor that improves the diagnostic accuracy of PET / CT. So far, limited studies have been reported using PET / CT in comparison with PET only and mainly proved additional value of PET / CT in malignant tumors in which conventional PET already had advantages over anatomical imaging. PET / CT appears to have a promising role in the field of radiotherapy planning. Another potential of PET / CT would be in the evaluation of tumors with low FDG uptake by way of CT or new PET tracers. PET / CT is in the stage of its early infancy and further studies remain to be performed to establish applications of PET / CT in clinical oncology. In this review, we will discuss the principle of PET, the background of the emergency of PET / CT, advantages, pitfalls, and debates of PET / CT along with clinical applications and future perspectives of thereof.
Early Diagnosis ; Emergencies ; Glucose ; Medical Oncology ; Metabolism ; Positron-Emission Tomography and Computed Tomography* ; Radiotherapy ; Recurrence ; Sensitivity and Specificity ; Whole Body Imaging

PET using FDG has been proposed as a functional whole body imaging modality that images various types of malignancies with relatively high sensitivity and specificity in a reasonably short time. It depicts a lesion based on abnormal glucose metabolism whereas CT as a high-resolution anatomical imaging detects malignant process mostly based on altered anatomy. PET / CT combines the advantages of PET and CT, and has a great value in early detection of disease, accurate staging or restaging, early assessment of treatment response, decision on therapeutic plans, and rapid localization of recurrence. Exact anatomical localization of a lesion with increased FDG uptake by CT is considered to be the most important factor that improves the diagnostic accuracy of PET / CT. So far, limited studies have been reported using PET / CT in comparison with PET only and mainly proved additional value of PET / CT in malignant tumors in which conventional PET already had advantages over anatomical imaging. PET / CT appears to have a promising role in the field of radiotherapy planning. Another potential of PET / CT would be in the evaluation of tumors with low FDG uptake by way of CT or new PET tracers. PET / CT is in the stage of its early infancy and further studies remain to be performed to establish applications of PET / CT in clinical oncology. In this review, we will discuss the principle of PET, the background of the emergency of PET / CT, advantages, pitfalls, and debates of PET / CT along with clinical applications and future perspectives of thereof.
Early Diagnosis ; Emergencies ; Glucose ; Medical Oncology ; Metabolism ; Positron-Emission Tomography and Computed Tomography* ; Radiotherapy ; Recurrence ; Sensitivity and Specificity ; Whole Body Imaging

18F-FDG PET scan is an useful functional whole body imaging modality that images various types of malignancies with relative high sensitivity and specificity in a reasonably rapid time. It depicts a lesion based on abnormal glucose metabolism whereas CT detects malignant process mostly based on altered anatomy. In patients with gastric cancers, PET scan detects only less than 50% of early cancers and 62-98% of advanced cancers. For initial T staging, anatomical imaging with a high spatial resolution is essential. There are a few studies on the prognostic significance of FDG uptake with inconsistent results. In spite of low sensitivity for lymph node staging, the specificity of CT and PET scan are very high, and the specificity of PET scan tends to be higher than that of CT. Detection of distant metastases on PET scan is dependent on tumor histology, degree of FDG uptake in primary tumors, sites of distant metastases, etc. There are only a few data available for the evaluation of recurrence detection and treatment responses using FDG PET scan. FDG PET scan has been used in the preoperative staging of colorectal cancer with some promising results. It seems to be the most useful in restaging recurrent tumors and selecting those patients who would benefit from surgery. PET scan has a potential value in assessing treatment responses after various combination of treatments in patients with colorectal cancer.
Fluorodeoxyglucose F18/*diagnostic use ; Gastrointestinal Neoplasms/pathology/radiography/*radionuclide imaging ; Humans ; Neoplasm Staging ; *Positron-Emission Tomography ; Radiopharmaceuticals/*diagnostic use ; Tomography, X-Ray Computed

Various molecular targeted therapies and diagnostic modalities have been developed for the treatment of hepatocellular carcinoma (HCC); however, HCC still remains a difficult malignancy to cure. Recently, the focus has shifted to cancer metabolism for the diagnosis and treatment of various cancers, including HCC. In addition to conventional diagnostics, the measurement of enhanced tumor cell metabolism using F-18 fluorodeoxyglucose (18F-FDG) for increased glycolysis or C-11 acetate for fatty acid synthesis by positron emission tomography/computed tomography (PET/CT) is well established for clinical management of HCC. Unlike tumors displaying the Warburg effect, HCCs vary substantially in terms of 18F-FDG uptake, which considerably reduces the sensitivity for tumor detection. Accordingly, C-11 acetate has been proposed as a complementary radiotracer for detecting tumors that are not identified by 18F-FDG. In addition to HCC diagnosis, since the degree of 18F-FDG uptake converted to standardized uptake value (SUV) correlates well with tumor aggressiveness, 18F-FDG PET/CT scans can predict patient outcomes such as treatment response and survival with an inverse relationship between SUV and survival. The loss of tumor suppressor genes or activation of oncogenes plays an important role in promoting HCC development, and might be involved in the “metabolic reprogramming” of cancer cells. Mutations in various genes such as TERT, CTNNB1, TP53, and Axin1 are responsible for the development of HCC. Some microRNAs (miRNAs) involved in cancer metabolism are deregulated in HCC, indicating that the modulation of genes/miRNAs might affect HCC growth or metastasis. In this review, we will discuss cancer metabolism as a mechanism for treatment resistance, as well as an attractive potential therapeutic target in HCC.
Carcinoma, Hepatocellular* ; Diagnosis ; Drug Resistance ; Electrons ; Fluorodeoxyglucose F18 ; Genes, Tumor Suppressor ; Glycolysis ; Humans ; Metabolism* ; MicroRNAs ; Molecular Targeted Therapy ; Neoplasm Metastasis ; Oncogenes ; Positron-Emission Tomography and Computed Tomography

Although high resolution ultrasonography (US) is helpful in the differentiation of suture granulomas from recurrent thyroid cancer in most cases, a definite diagnosis cannot always be made. We report a case that mimicked recurrent thyroid cancer on US and 2-[fluorine-18] fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET), but diagnosis of a suture granuloma was confirmed by a US-guided fine needle aspiration biopsy (FNAB). In order to avoid unnecessary operations, the differential diagnosis between postoperative suture granulomas and recurrent cancer is important.
Thyroidectomy/*adverse effects ; Thyroid Neoplasms/diagnosis/pathology/ultrasonography ; Sutures/*adverse effects ; Positron-Emission Tomography ; Neoplasm Recurrence, Local/diagnosis/pathology/ultrasonography ; Humans ; Granuloma, Foreign-Body/*diagnosis/etiology/ultrasonography ; Female ; Diagnosis, Differential ; Biopsy, Fine-Needle ; Adult

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 AND 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+/-1.4 cm(0.5~5 cm). In 13 PTC with negative FDG uptake, the mean size of those was 0.5+/-0.2 cm (0.2~0.9 cm). All PTC larger than 1cm (2.5+/-1.4 cm, 1~5 cm) have positive FDG uptake (peak SUV=6.4+/-5.7, 1.7~22.7). Among the micropapillary thyroid cancer (microPTC; PTC smaller than 1cm), 8 microPTC show positive FDG uptake(peak SUV=2.9+/-1.3, 1.7~5.5), while 13 microPTC show negative finding(peak SUV=1.3+/-0.2, 1.1~1.7). The size of microPTC with positive FDG uptake is significantly larger than that of microPTC with negative FDG uptake (0.7+/-0.1 cm vs 0.4+/-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.
Biopsy, Fine-Needle ; Humans ; Thyroid Gland* ; Thyroid Neoplasms* ; Thyroid Nodule