Tatsuro Tsuchida

UNLABELLED: Recent reports have indicated the value and limitations of (18)F-FDG PET and (201)Tl SPECT for determination of malignancy. We prospectively assessed and compared the usefulness of these scintigraphic examinations as well as (18)F-FDG PET delayed imaging for the evaluation of thoracic abnormalities. METHODS: Eighty patients with thoracic nodular lesions seen on chest CT images were examined using early and delayed (18)F-FDG PET and (201)Tl-SPECT imaging within 1 wk of each study. The results of (18)F-FDG PET and (201)Tl SPECT were evaluated and compared with the histopathologic diagnosis. RESULTS: Fifty of the lesions were histologically confirmed to be malignant, whereas 30 were benign. On (18)F-FDG PET, all malignant lesions showed higher standardized uptake value (SUV) levels at 3 than at 1 h, and benign lesions revealed the opposite results. Correlations were seen between (18)F-FDG PET imaging and the degree of cell differentiation in malignant tumors. No significant difference in accuracy was found between (18)F-FDG PET single-time-point imaging and (201)Tl SPECT for the differentiation of malignant and benign thoracic lesions. However, the retention index (RI) of (18)F-FDG PET (RI-SUV) significantly improved the accuracy of thoracic lesion diagnosis. Furthermore, (18)F-FDG PET delayed imaging measuring RI-SUV metastasis was useful for diagnosing nodal involvement and it improved the specificity of mediastinal staging. CONCLUSION: No significant difference was found between (18)F-FDG PET single-time-point imaging and (201)Tl SPECT for the differentiation of malignant and benign thoracic lesions. The RI calculated by (18)F-FDG PET delayed imaging provided more accurate diagnoses of lung cancer.

OBJECTIVE: The purpose of this study was to determine whether the addition of positron emission tomography (PET) with the radiotracer FDG to cross-sectional imaging, such as CT, increases accuracy in the detection of tumor spread. SUBJECTS AND METHODS. Fifteen patients who were thought to have ovarian cancer on the basis of the results of physical examination, sonography findings, and level of serum cancer antigen 125 were enrolled over an 11-month period. After screening, patients underwent two imaging examinations-abdominopelvic CT and whole-body FDG PET- within 2 weeks before surgery. Also before surgery, staging accuracy was assessed separately using CT with or without FDG PET (which was based on modifications of the International Federation of Gynecology and Obstetrics [FIGO] criteria). The results of the histology and surgery findings were used to assess the accuracy of the scanning findings. RESULTS: Staging revealed stage III disease in seven patients (IIIC, n = 6; IIIB, n = 1), stage II in three (IIC, n = 2; IIB, n = 1), and stage I in five (IC, n = 3; IA, n = 2), according to the FIGO criteria. Although CT staging correlated with postoperative staging in eight (53%) of 15 patients, consensus evaluation of CT with FDG PET staging improved correlation with postoperative staging in 13 (87%) of 15 patients. CONCLUSION: The addition of FDG PET to CT increases accuracy in staging of ovarian cancer.

We evaluated whether tracer FDG uptake, quantified as an SUV by PET in ovarian epithelial tumors, correlates with clinical stage, tumor grade, cell proliferation and glucose metabolism, all of which are biomarkers for response to chemotherapy, prognosis and overall survival in ovarian cancer patients. Seventeen patients suspected of having ovarian cancer by physical examination, tumor marker analysis and anatomic imaging (such as sonography, CT and/or MRI) underwent whole-body FDG-PET within the 2 weeks prior to surgery. Seventeen epithelial ovarian tumor specimens (13 malignant tumors, 5 at stage I, 2 at stage II, 6 at stage III; 2 borderline tumors; and 2 benign lesions) were available for pathologic evaluation. They were graded histopathologically, and immunohistochemistry for MIB-1 (proliferation index marker) and GLUT-1 was performed. Correlation between FDG uptake and clinical stage, GLUT-1 expression, MIB-1 LI and histologic grading score was determined. No positive correlation was observed between FDG uptake and clinical stage (p=0.14). Intensity of GLUT-1 expression (r=0.76, p=0.001), MIB-1 LI (r=0.457, p=0.014) and histologic grading score (r=0.692, p=0.005) showed statistically significant positive correlations with FDG uptake. Stepwise logistic regression analysis revealed that expression of GLUT-1 transporters was the strongest parameter (r=0.760, p=0.0004) by which to predict positive FDG uptake. Therefore, glucose consumption, as determined by analysis of SUVs in FDG-PET, may be a noninvasive biomarker for ovarian epithelial tumors.

OBJECTIVE: The purpose of our study was to determine whether (18)F-FDG PET can be used to differentiate among common enhancing brain tumors such as lymphoma, high-grade glioma, and metastatic brain tumor. MATERIALS AND METHODS: We evaluated 34 patients with an enhancing brain tumor on MRI, including seven lymphomas, nine high-grade gliomas, and 18 metastatic tumors. All patients also underwent FDG PET. For PET image analysis, regions of interest were placed over the tumor (T), contralateral cortex (C), and white matter (WM). Average and maximum pixel values were determined at each site. On the basis of these measurements, average and maximum standard uptake values (SUV(avg) and SUV(max)) were calculated, along with activity ratios (T/C(avg), T/WM(avg), T/WM(max), and T/C(max)), and comparisons among lesions were then made. RESULTS: All parameters were significantly higher for lymphoma than for other tumors (p < 0.01). High-grade gliomas showed significantly higher SUV(avg) and SUV(max) than metastatic tumors (p < 0.05). Other parameters did not differ between lesion types. SUV(max) was the most accurate parameter for distinguishing lymphomas. Using an SUV(max) of 15.0 as a cutoff for diagnosing CNS lymphoma, only one high-grade glioma was found as a false-positive (SUV(max), 18.8). CONCLUSION: FDG PET may be useful for differentiating common enhancing malignant brain tumors, particularly lymphoma versus high-grade glioma and metastatic tumor. FDG PET can provide useful information for distinguishing between lymphoma and other malignant enhancing brain tumors and is recommended when differential diagnoses are difficult to narrow using MRI alone.