Mitsuyuki Miyakubo

PET and PET/CT using 18F-FDG in the diagnosis and management of cancer patients

Positron emission tomography (PET) using 2-18F-fluoro-2-deoxy-D-glucose (FDG), a radioactive derivative of glucose, is an advanced imaging tool, based on the increased glucose consumption of cancer cells. FDG-PET provides information that is not obtainable with other imaging modalities, and is very effective in the diagnosis and management of patients with various types of cancers. However, there are some limitations, such as low FDG uptake in some cancers, substantial FDG uptake in inflammatory cells, and the lack of anatomical information and poor imaging quality of PET. A recently developed integrated PET/computed tomography (CT) system, which combines a PET camera and CT scanner in a single session, has overcome these drawbacks by providing both anatomical and functional imaging at the same position. PET and/or PET/CT using FDG is clinically useful in the detection of cancer, the differentiation of malignant and benign lesions, the staging of cancer before therapy, and the assessment of cancer therapy, as well as for determining the recurrence after therapy of most cancers, including lung cancer, gastrointestinal cancer, breast cancer, and malignant lymphoma. PET/CT has become the new standard approach to imaging in the diagnosis and management of many cancer patients.

Present role and future prospects of positron emission tomography in clinical oncology

Positron emission tomography (PET) has emerged as a significant molecular imaging technique in clinical oncology and cancer research. PET with 18F‐fluorodeoxyglucose (18F‐FDG) demonstrates elevated glucose consumption by tumor cells, and is used clinically for the accurate staging and restaging of cancer, planning of radiotherapy, and predicting response or lack of response in the early stages of treatment. Combined PET and computed tomography (PET‐CT) provides both functional and morphological information of the disease to allow accurate diagnosis of cancer. PET with new radiotracers such as protein synthesis markers and proliferation markers, as well as hypoxia and receptor‐binding agents, will offer patient‐specific images in order to yield tailored diagnostic and prognostic information. (Cancer Sci 2006; 97: 1291–1297)

Diagnosis of maxillofacial tumor withl-3-[18F]-fluoro-α-methyltyrosine (FMT) PET: a comparative study with FDG-PET

Objectives: To comparel-3-[18F]-fluoro-α-methyltyrosine (FMT)-positron emission tomography (PET) and 2-[18F]-fluoro-2-deoxy-d-glucose (FDG)-PET in the differential diagnosis of maxillofacial tumors.Methods: This study included 36 patients (16 males, 20 females; 31–90 years old) with untreated malignant tumors (34 squamous cell carcinoma, one mucoepidermoid carcinoma, one rhabdomyosarcoma) and seven patients (five males, two females; 32–81 years old) with benign lesions. In all patients, both FMT-PET and FDG-PET were performed within two weeks before biopsy or treatment of the lesions. To evaluate the diagnostic usefulness of FMT-PET and FDG-PET, visual interpretation and semiquantitative analysis were performed. PET images were rated according to the contrast of tumor uptake as compared with background, and were statistically analyzed. As a semiquantitative analysis, standardized uptake values (SUV) of the primary tumors were measured, and the SUV data were analyzed using receiver operating characteristic (ROC) curves.Results: The mean SUV of the malignant lesions were significantly higher than those of the benign lesions in both FMT-PET (2.62±1.58 vs. 1.20±0.30, p<0.01) and FDG-PET (9.17±5.06 vs. 3.14±1.34, p<0.01). A positive correlation (r=0.567, p<0.0001, n=46) was noted between FMT and FDG. ROC analysis revealed that there was no statistically significant difference in SUVs between FMT and FDG for differentiating malignant tumors. In 27 of 36 patients, FMT-PET had better contrast of malignant tumor visualization to the surrounding normal structures by visual assessment (p<0.005, binomial proportion test).Conclusions: Differential diagnosis of FMT-PET based on the uptake in maxillofacial tumors is equivalent to FDG-PET. However, the contrast of FMT uptake between maxillofacial tumors and the surrounding normal structures is higher than that of FDG, indicating the possibility of accurate diagnosis of maxillofacial tumors by FMT-PET.

Clinicopathological presentation of varying 18F-FDG uptake and expression of glucose transporter 1 and hexokinase II in cases of hepatocellular carcinoma and cholangiocellular carcinoma

We report the results of 18F-fluorodeoxyglucose positron emission tomography (FDG PET) and immunohistochemical staining of glucose transporter 1 (Glut-1) and hexokinase II (HK-II) in patients with hepatocellular carcinoma (HCC) and cholangiocellular carcinoma (CCC) to observe the variation in 18F-FDG uptake and variation in expression of Glut-1 and HK-II in these hepatic tumors. In the case of HCC, moderate 18F-FDG uptake and strong expression of HK-II were detected, whereas Glut-1 was not expressed. Conversely, CCC showed high 18F-FDG uptake and increased expression of Glut-1 but HK-II was not expressed. The variation in the 18F-FDG uptake and expression of Glut 1 and HK-II in HCC and CCC might be owing to the difference in origin and the different mechanisms involved in glucose uptake, rate of glucose transporters, and hexokinase activity involved in the glycolytic pathway.