Value of FDG-PET/CT findings revised using an anthropomorphic body phantom for the evaluation of tumor malignancy grade in small-sized lung adenocarcinomas: A multicenter study

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Background: The malignant behavior of small lung adenocarinomas (AD), which have been detected with increasing frequency recently, has not yet been clearly evaluated, and an understanding of this biological characteristic is vital for selecting the appropriate therapeutic strategy. We examined the malignancy grade of small lung ADs using FDG-PET/CT (PET), in addition to high-resolution CT (HRCT) and pathologic evaluation in a multicenter setting. Methods: A total of 204 patients with cT1N0M0 AD underwent PET and HRCT, followed by complete resection with lymph node dissection. The associations between components of bronchioloalveolar carcinoma (BAC) on pathologic examination and maximum standardized uptake value (maxSUV) on PET, ground-glass opacity (GGO) ratio and tumor disappearance rate (TDR) on HRCT were examined, and these findings were analyzed in relation to pathologic features and surgical outcomes. To reduce the errors in PET machines used for this analysis, maxSUV data were adjusted using an anthropomorphic body phantom of the NEMA standards (corrected maxSUV). Results: Examination of tumor aggressiveness based on the presence of lymphatic, vascular and pleural invasion, and of nodal metastasis, showed that maxSUV, BAC ratio, TDR, and GGO ratio, in the order, can reflect the malignancy grade. MaxSUV and BAC ratio were also valuable prognostic predictors of the disease-free survival. There were no significant differences in the values between maxSUV and corrected maxSUV. Although BAC ratio was significantly associated with maxSUV, GGO ratio and TDR (all p<0.0001), the degree of association with maxSUV (R2=0.2533) was weaker than that with GGO (R2=0.5843) ratio or TDR (R2=0.5123). Conclusions: A higher maxSUV reflects an aggressive malignant behavior of cT1N0M0 ADs, independently of BAC component. Assessment by PET in addition to HRCT is useful for selection of the appropriate treatment strategy for small lung AD.

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No significant financial relationships to disclose.

Evaluation of 18F-2-deoxy-2-fluoro-glucose positron emission tomography for gastric cancer screening in asymptomatic individuals undergoing endoscopy

(18)F-2-deoxy-2-fluoro-glucose Positron Emission Tomography (FDG-PET) has been recently proposed as a promising cancer-screening test. However, the validity of FDG-PET in cancer screening has not been evaluated. We investigated the sensitivity of FDG-PET compared with upper gastric endoscopy in gastric cancer screening for asymptomatic individuals. A total of 2861 consecutive subjects (1600 men and 1261 women) who were asymptomatic and who underwent both FDG-PET and upper gastrointestinal endoscopy between 1 February 2004 and 31 January 2005 were included in this study. Both endoscopists and a radiologist were unaware of the results of the other diagnostic tests. The FDG-PET images were examined using criteria determined by the pattern of FDG accumulation. Sensitivity and specificity of FDG-PET were calculated compared with endoscopic diagnosis as the gold standard. Among 2861 subjects enrolled in the study, there were 20 subjects with gastric cancer, of whom 18 were T1 in depth of cancer invasion. Positive FDG-PET results were obtained only in 2 of the 20 cancer subjects. The calculated sensitivity and specificity for overall gastric cancers were 10.0% (95% confidence interval (CI): 1.2-31.7%) and 99.2% (95% CI: 98.8-99.5%), respectively. (18)F-2-deoxy-2-fluoro-glucose Positron Emission Tomography was poorly sensitive for detection of gastric cancer in the early stages.