Observer variation study of the assessment and diagnosis of incidental colonic FDG uptake.

PURPOSE: The aim of this study was to evaluate the interpretations of incidental colonic 18F-FDG uptake made by 10 experienced readers and to more clearly identify the pattern of suspicious colonic FDG uptake. The potential contributions of delayed FDG-PET scanning and of immune fecal occult blood testing (FOBT) in making a diagnosis were also analyzed. MATERIALS AND METHODS: Visual interpretations by 10 readers were made for 147 FDG uptake sites from 126 PET scans (cancer, 38 sites; adenoma, 43 sites; and no abnormality, 66 sites) with colonic FDG uptake. Assessments for the early FDG-PET images were (1) FDG uptake pattern, (2) FDG uptake degree, and (3) likelihood of malignancy. For the delayed images, the assessments were (1) change in the FDG uptake position, (2) change in FDG uptake degree, and (3) likelihood of malignancy. The results of FOBT were analyzed independently of the visual interpretations. RESULTS: Interobserver agreement (κ) was 0.501 for assessing FDG uptake patterns, while agreement on assessing changes in uptake degree and changes in uptake position between early and delayed imaging were low (κ = 0.213-0.229). Logistic regression analysis indicated that 'FDG uptake patterns' and 'FDG uptake degree' were significantly related to decide on the suspicion of malignancy (p < 0.001) and the final result (p < 0.001). "Small localized" and "large irregular localized" types had a high probability of a lesion regardless of either (1) FDG uptake degree or (2) variation in the uptake between the early and the delayed image. The delayed image decreased false-positive cases for some FDG uptake patterns, but it had little impact on distinguishing clearly between "cancer or adenoma" and "normal". The addition of FOBT had little impact on the diagnosis. CONCLUSION: There was highest agreement among readers with respect to the recognition of specified colonic FDG uptake patterns, and this pattern recognition had the most influence on the diagnosis. "Small localized" and "large irregular localized" types had a high probability of a lesion. The addition of delayed imaging and of FOBT results to the early imaging did not have much impact on the diagnosis.

Assessment of FDG retention differences between the FDG-avid benign pulmonary lesion and primary lung cancer using dual-time-point FDG-PET imaging.

PURPOSE: The aim of this study was to clarify FDG retention differences between FDG-avid benign pulmonary lesions (BPLs) and primary lung cancers (PLCs), and between tuberculous and non-tuberculous BPLs using dual-time-point FDG-PET imaging. METHODS: Thirty-four BPLs and 47 PLCs with a maximal standardized uptake value (SUVmax) >2.5 and a maximal axial diameter >10 mm were enrolled. We compared the retention index (RI) among different types of lesions, and evaluated the relationship between RI and SUVmax at 1 h (SUV1). Glucose transporter-1 (Glut-1) and hexokinase (HK)-2 expression was assessed in eight non-tuberculous BPLs. RESULTS: BPLs and PLCs showed similar high RIs (mean ± SD 33.6 ± 22.6 and 32.5 ± 23.7, respectively; p = 0.95). In BPLs, both tuberculous and non-tuberculous lesions showed high RIs (39.1 ± 25.8 and 30.3 ± 20.3, respectively; p = 0.43). However, BPLs and PLCs exhibited a different relationship between RI and SUV1. BPLs tended to show lower RIs with higher SUV1s, and a mild negative correlation, whereas PLCs showed persistent high RIs and no significant correlation. Glut-1 and HK-2 expression was found in 75 and 12.5 % of non-tuberculous BPLs, respectively. CONCLUSIONS: FDG-avid BPLs could show high RIs regardless of their being tuberculous and non-tuberculous lesions, and no significant difference with PLC RIs was found. FDG-avid BPLs and PLCs showed different relationships between RI and SUV1, and it seemed to be related with different mechanisms of high FDG retention. However, the mechanisms of high FDG retention in FDG-avid BPLs remain unclear, and this matter requires further investigation.

Continuous butanol fermentation from xylose with high cell density by cell recycling system.

A continuous butanol production system with high-density Clostridium saccharoperbutylacetonicum N1-4 generated by cell recycling was established to examine the characteristics of butanol fermentation from xylose. In continuous culture without cell recycling, cell washout was avoided by maintaining pH>5.6 at a dilution rate of 0.26 h(-1), indicating pH control was critical to this experiment. Subsequently, continuous culture with cell recycling increased cell concentration to 17.4 g L(-1), which increased butanol productivity to 1.20 g L(-1) h(-1) at a dilution rate of 0.26 h(-1) from 0.529 g L(-1) h(-1) without cell recycling. The effect of dilution rates on butanol production was also investigated in continuous culture with cell recycling. Maximum butanol productivity (3.32 g L(-1) h(-1)) was observed at a dilution rate of 0.78 h(-1), approximately 6-fold higher than observed in continuous culture without cell recycling (0.529 g L(-1) h(-1)).

[Assessment of diagnostic criteria for FDG-PET cancer screening program according to the interpretation of FDG-PET and combined examination].

OBJECTIVE: The aim of this study is to establish the diagnostic criteria for FDG-PET cancer screening program of four kinds of organ (breast, thyroid, lung and colon/rectum) according to the interpretation of FDG-PET cancer screening program of the case with proved clinical outcome. METHODS: Among FDG-PET cancer screening examinations performed in two PET centers during 2003 to 2006, two hundreds of examinations with proved clinical outcome were evaluated. Interpretation of breast ultrasonography, thyroid ultrasonography, chest CT and fecal occult blood testing, which were regarded as combined examinations, were performed together with the interpretation of FDG-PET images. RESULTS: As a result of the interpretation, localized FDG accumulating site in all four organs should be recommended for further inspections. In addition, essential point for diagnosis was considered as follows; (1) check over the slight localized FDG accumulation with screening of breast region, (2) combine chest CT with FDG-PET for the evaluation of lung region and (3) check up the shift of FDG accumulation between early and delayed phase with screening of colon/rectum region. CONCLUSIONS: According to the interpretation results of this study, we establish diagnostic criteria of FDG-PET and combined examination of four kinds of organ.