Reiko Kameyama

Detection of Hepatocellular Carcinoma Using 11C-Choline PET: Comparison with 18F-FDG PET

The purpose of this study was to retrospectively investigate the feasibility of 11C-choline PET, compared with 18F-FDG PET, for the detection of hepatocellular carcinoma (HCC). Methods: A total of 16 HCC lesions in 12 patients were examined with both 11C-choline PET and 18F-FDG PET. Tumor lesions were identified as areas of focally increased uptake, exceeding that of surrounding noncancerous liver tissue. For semiquantitative analysis, the tumor-to-liver (T/L) ratio was calculated by dividing the maximal standardized uptake value (SUV) in HCC lesions by the mean SUV in noncancerous liver tissue. Results: 11C-choline PET showed a slightly higher detection rate than did 18F-FDG PET for detection of HCC (63% vs. 50%, respectively), although this difference was not statistically significant. 11C-choline PET had a better detection rate for moderately differentiated HCC lesions but not for those poorly differentiated (75% vs. 25%, respectively). In contrast, 18F-FDG PET exhibited the opposite behavior, with corresponding detection rates of 42% and 75%, respectively. The mean 11C-choline SUV and T/L ratio in moderately differentiated HCC lesions were higher than those in poorly differentiated HCC lesions. In contrast, the mean 18F-FDG SUV and T/L ratio in poorly differentiated HCC were higher than those in moderately differentiated HCC. These differences, however, were also not statistically significant. Conclusion: 11C-choline PET had a better detection rate for moderately differentiated HCC lesions but not for poorly differentiated HCC lesions, whereas 18F-FDG PET produced the opposite result. 11C-choline is a potential tracer to complement 18F-FDG in detection of HCC lesions.

Detection of gastric cancer using 18F-FLT PET: comparison with 18F-FDG PET.

PurposeWe prospectively investigated the feasibility of 3′-deoxy-3′-18F-fluorothymidine (FLT) positron emission tomography (PET) for the detection of gastric cancer, in comparison with 2-deoxy-2-18F-fluoro-d-glucose (FDG) PET, and determined the degree of correlation between the two radiotracers and proliferative activity as indicated by Ki-67 index.MethodsA total of 21 patients with newly diagnosed advanced gastric cancer were examined with FLT PET and FDG PET. Tumour lesions were identified as areas of focally increased uptake, exceeding that of surrounding normal tissue. For semiquantitative analysis, the maximal standardized uptake value (SUV) was calculated.ResultsFor detection of advanced gastric cancer, the sensitivities of FLT PET and FDG PET were 95.2% and 95.0%, respectively. The mean (±SD) SUV for FLT (7.0 ± 3.3) was significantly lower than that for FDG (9.4 ± 6.3 p < 0.05). The mean FLT SUV and FDG SUV in nonintestinal tumours were higher than in intestinal tumours, although the difference was not statistically significant. The mean (±SD) FLT SUV in poorly differentiated tumours (8.5 ± 3.5) was significantly higher than that in well and moderately differentiated tumours (5.3 ± 2.1; p < 0.04). The mean FDG SUV in poorly differentiated tumours was higher than in well and moderately differentiated tumours, although the difference was not statistically significant. There was no significant correlation between Ki-67 index and either FLT SUV or FDG SUV.ConclusionFLT PET showed as high a sensitivity as FDG PET for the detection of gastric cancer, although uptake of FLT in gastric cancer was significantly lower than that of FDG.

11C-acetate PET in the evaluation of brain glioma: comparison with 11C-methionine and 18F-FDG-PET.

PurposeThe aim of the study is to retrospectively investigate the usefulness of 11C-acetate (ACE)-positron emission tomography (PET) for evaluation of brain glioma, in comparison with 11C-methionine (MET) and 2-deoxy-2-18F-fluoro-d-glucose (FDG).ProceduresFifteen patients with brain glioma referred to initial diagnosis were examined with ACE, MET, and FDG-PET. Five patients had low-grade gliomas (grade II), three had anaplastic astrocytomas (grade III), and seven had glioblastomas (grade IV). PET results were evaluated by visual and semiquantitative analysis. For semiquantitative analysis, the standardized uptake value (SUV) and tumor to contralateral normal gray matter (T/N) ratio were calculated. The sensitivity for detection of high-grade gliomas was calculated using visual analysis.ResultsSensitivities of ACE, MET, and FDG were 90%, 100%, and 40%, respectively. ACE and MET T/N ratios were significantly higher than that of FDG. ACE and FDG SUV in high-grade gliomas were significantly higher than that in low-grade gliomas. No significant differences were observed using MET.ConclusionsACE PET is a potentially useful radiotracer for detecting brain gliomas and differentiating high-grade gliomas.

Early Assessment of Therapeutic Response using FDG PET in Small Cell Lung Cancer

PurposeWe evaluated the ability of 2-deoxy-2-18F-fluoro-d-glucose (FDG) positron emission tomography (PET) in the early assessment of therapeutic response in patients with small cell lung cancer (SCLC).ProceduresFDG PET studies were performed before (baseline PET), after the first cycle of chemotherapy (early PET), and after completion of therapy (final PET) in 12 patients with SCLC. The standardized uptake value (SUVmax) was measured. Metabolic response was defined as a reduction in SUVmax of more than 20% on the early PET, compared with the baseline PET. Tumor response after completion of therapy was evaluated according to the Response Evaluation Criteria in Solid Tumors (RECIST).ResultsEleven patients were classified as metabolic responders and had a mean (±SD) reduction in SUVmax of 57.9 ± 10.3%. The remaining one patient was classified as a metabolic nonresponder with a reduction in SUVmax of 13.5%. In all patients, metabolic response after the first cycle of chemotherapy was associated with subsequent response according to RECIST.ConclusionsFDG PET has the potential to identify the therapeutic response in patients with SCLC as early as after the first cycle of chemotherapy.

Detection of colorectal cancer using 18F-FLT PET: comparison with 18F-FDG PET

ObjectiveWe investigated the feasibility of 3′-deoxy-3′-18F-fluorothymidine (FLT) positron emission tomography (PET) for the detection of colorectal cancer, in comparison with 2-deoxy-2-18F-fluoro-D-glucose (FDG) PET, and investigated correlation of the two radiotracers used with proliferative activity as indicated by Ki-67 index. MethodsA total of 26 patients with newly diagnosed colorectal cancer were examined with FLT PET and FDG PET. Tumor lesions were identified as areas of focally increased uptake, exceeding that of surrounding normal tissue. For semiquantitative analysis, the maximal standardized uptake value (SUV) was calculated. ResultsIn all 26 patients, colorectal cancers were detected by both FLT PET and FDG PET. The mean (±SD) values of FLT SUV in colon cancer (5.4±2.4) and in rectal cancer (5.6±1.3) were significantly lower than the corresponding values of FDG SUV (12.4±6.3 and 12.5±4.7, respectively) (P<0.003). There was no significant correlation between Ki-67 index and either FLT SUV or FDG SUV. ConclusionAlthough uptake of FLT was found to be significantly lower than that of FDG, both FLT PET and FDG PET were able to detect colorectal cancers in all 26 patients. Neither of the two radiotracers used was correlated with proliferative activity.

Diagnostic value of kinetic analysis using dynamic 18F-FDG-PET in patients with malignant primary brain tumor.

ObjectiveThe purpose of this study was to evaluate the efficacy of quantitative imaging of glucose metabolism with positron emission tomography (PET) using kinetic analysis for differentiating between high-grade glioma and central nervous system (CNS) lymphoma. MethodsDynamic fluorine-18-fluorodeoxyglucose (18F-FDG)-PET scans obtained in 20 patients with high-grade glioma (World Health Organization grade III, five lesions; grade IV, 15 lesions) and in 12 patients with CNS lymphoma (16 lesions) were retrospectively reviewed. Applying a three-compartment model, parametric images of K1, k2, k3, and k4 and cerebral metabolic rate of glucose (CMRGlc) were obtained. ResultsOn visual analysis, one grade III glioma lesion showed an increase of K1, k2, and k3 values as observed on their respective images. Four grade IV glioma lesions showed an increase of K1 and k2, 11 of k3, and six of CMRGlc on their respective images. Fourteen CNS lymphoma lesions showed an increase of K1, 16 of k3, two of k4, and 14 of CMRGlc. Both k3 and CMRGlc values (mean±SD) of CNS lymphoma (0.096±0.046 and 77.4±37.7, respectively) were significantly higher than those of the normal gray matter (0.059±0.015 and 41.3±9.3, respectively; P<0.007 and P<0.002, respectively). The k3 value of CNS lymphoma was significantly higher than that of grade III (0.058±0.022) and grade IV (0.065±0.024) gliomas (P<0.03 and P<0.04, respectively). The CMRGlc value of CNS lymphoma was significantly higher than that of grade III (33.8±7.8) and grade IV (41.5±23.1) gliomas (P<0.001 and P<0.004, respectively). The value of k2 of CNS lymphoma was significantly lower than that of grade IV glioma (P<0.05). ConclusionThe direct measurement of the regional rate constants by kinetic analysis might be useful for the delineation of CNS lymphoma and for differential diagnosis of high-grade glioma and CNS lymphoma.

18F)Fluorodeoxyglucose accumulation as a biological marker of hypoxic status but not glucose transport ability in gastric cancer

BackgroundThe use of [18F] 2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) for detection of gastric cancer is often debated because FDG uptake varies for each patient. The purpose of this study was to clarify the molecular mechanisms involved in FDG uptake.Material and methodsFifty patients with gastric cancer who underwent FDG-PET and gastrectomy were studied. Snap-frozen tumor specimens were collected and examined by real-time PCR for relationships between maximum standardized uptake value (SUV) and mRNA expression of the following genes: glucose transporter 1 (GLUT1), hexokinase 2 (HK2), hypoxia-inducible factor 1α (HIF1α), and proliferating cell nuclear antigen (PCNA).ResultsTumor size was the only clinicopathological parameter that significantly correlated with SUV. Transcripts for the genes evaluated were about three-fold higher in malignant specimens than in normal mucosa, although only HIF1α was significantly correlated with SUV. When divided into intestinal and non-intestinal tumors, there was a significant correlation between SUV and tumor size in intestinal tumors. Interestingly, the weak association between SUV and HIF1α expression in intestinal tumors was substantially stronger in non-intestinal tumors. No correlation was found between SUV and mRNA expression of other genes in intestinal or non-intestinal tumors.ConclusionSUV was correlated with HIF1α, but not PCNA, HK2, or GLUT1 expression. FDG accumulation could therefore represent tissue hypoxia rather than glucose transport activity for aggressive cancer growth.

Correlation of 18F-FLT uptake with equilibrative nucleoside transporter-1 and thymidine kinase-1 expressions in gastrointestinal cancer.

PurposeWe examined equilibrative nucleoside transporter-1 (ENT1) and thymidine kinase-1 (TK1) messenger ribonucleic acid (mRNA) expressions in cancer tissue samples to elucidate the mechanism of 3′-deoxy-3′-18F-fluorothymidine (FLT) uptake by positron emission tomography (PET) scan in gastrointestinal cancer. MethodsA total of 21 patients with newly diagnosed gastrointestinal cancer were examined with FLT PET. Tumor lesions were identified as areas of focally increased uptake, exceeding that of surrounding normal tissue. For semiquantitative analysis, the maximal standardized uptake value (SUV) was calculated. The expressions of ENT1 and TK1 in cancer tissue samples were compared with that of FLT SUV. ResultsOf all gastrointestinal cancer lesions only one gastric cancer showed focally increased uptake of FLT PET. The mean (±standard deviation) FLT SUV in gastrointestinal cancer was 5.48±1.87. There was no significant correlation between FLT SUV and ENT1 (P=0.90) mRNA expression. There was a significant correlation between FLT SUV and TK1 mRNA expression (P<0.05). ConclusionResults of this preliminary study indicate that TK1 activity is an important determinant of FLT uptake in gastrointestinal cancer. In this study, it was found that ENT1 activity and FLT uptake were not related.